STUDIES OF NEW METHODS FOR THE ANALYSIS OF HYDRAZINE …

STUDIES OF NEW METHODS FOR

THE ANALYSIS OF HYDRAZINE

COMPOUNDS AND THE USE OF HYDRAZINE

AS AN ANALYTICAL REAGENT

BY

HUGE E. MALONE B .A. (.WITTENBERG)

MSc CEDIN.BURGH

A

THES IS

SUBMITTED FOR THE DEGREE

OF

DOCTOR OF PHILOSOPHY

FACULTY OF PURE SCIENCE

UNIVERSITY OF EDINBURGH

FEBRUARY 1974

TWPT tiP ATT(ThT

This thesis has been composed by me; it is based on original

experimental work that I have conducted and includes details of, or

reference to, original experimental studies that I have conducted

in the University of Edinburgh and elsewhere.

This thesis does not include any work submitted by me for any

other degree or professional qualification at any time.

i

Table of Contents

INTRODUCTION

OXIDATION OF HYDRAZINES

BASICITY OF HYDRAZINES

HYDRAZINE AS AN ANALYTICAL REAGENT

Carbonyls

Anhydrides

Isocyanate and Isothiocyanate

DETERMINATION OF MIXTURES OF HYDRAZINE, MON OMETHYLHYDRAZ INE AND 1,1-DINE THYLRYDRAZIME

REACTIONS

EXPERIMENTAL

Preparation of Sample

Determination of Total Hydrazine and Monomethyihydrazine

Determination of Monomethyihydrazine

Analysis of Mixtures of Hydrazine and 1, 1-Dimethyihydrazine

Determination of 1, l-Dimethylhydrazine

CALCULATIONS

THREE HYDRAZINES

Analysis of Mixtures of Hydrazine, Monomethyihydrazine and 1,1-Dimethy1hydrazine


Determination of Hydrazine, Monomethyl-Hydrazine + 1.1-Dimethylhydrazine

CALCULATIONS

RESULTS AND DISCUSSION

DISCUSSION

Section

1

Page

1

5

7

9

9

11

12

15

16

17

17

17

18

18

18

19

19

19

19

20

21

24

ii

Table of Contents (Continued)

Section

3 AN ACID-BASE ISOCYANATE METHOD FOR THE ANALYSIS OF ADMIXTURES OF HYDRAZINE WITH 1, 1-DIMETHYLHYDRAZINE, AND MONOMETHYL-HYDRAZINE WITH 1, l-DIMETHYLHYDRAZINE

REACTIONS

EXPERIMENTAL


Determination of Total 1{ydrazines

Determination of 1,1- Dimethy1hydrazine

CALCULATIONS


4 DETERMINATION OF ALDEHYDES, ANHYDRIDES,, ISOCYANATES AND ISOTHIOCYANATES

REACTIONS

EXPERIMENTAL


Determination of Aldehydes, Anhydrides, Isocyanates

Determination of Isothiocyanates

5 THE ANALYSIS OF ISOCYANATE - ISOTHIOCYANATE ADMIXTURES USING HYDRAZINE

EXPERIMENTAL

Preparation of Samples

Determination of Total Isocyanate-Isothiocyanate Mixture

Determination of Isothiocyanate

CALCULATIONS


Page

26

26

27

27

27

27

28

28

35

35

36

36

36

36

44

44

44

44

45

45

45

iii

Table of Contents (Continued)

Section

MISCELLANEOUS STUDIES

Page

52

GRAVIMETRIC

PRELIMINARY DATA

COLORIMETRIC

HYDRAZINE AS A REAGENT

PRELIMINARY DATA

52

52

53

55

55

59

62

7 CLOSURE

REFERENCES

iv

LIST OF TABLES

TABLE PAGE

1.1 Method for Hydrazine Determination (Oxidation) • . • • 2

1.11 Method for Hydrazine Determination (Basicity) ...... 7

1.111 Methods for Hydrazine use as an Analytical Reagent . . . . . . . . . . . . . . . . . . . . . . . . 8-

2.1 Reactivity of Various Aldehydes with N2H4 and MMH ...................... 21

2.11 Effect of Time, Temperature and Excess Aldehyde on N

2 H 4 and Mt'IH ................ 22

2.111 Analysis of N 2H4-MMH Mixtures .............. 23

2.IV Analyses of N2H4-MMH-UDMR Mixtures ........... 24

3.1 Effect of Isocyanates on Various Hydrazines in Alcoholic Medium using 0.1N HC1/Propanol ........ 28

3.11 Comparison of Acetic Acid and Dioxan as Non-Aqueous Solvents for the Analysis of Hydrazine-UDNH by the Isocyanate Reaction ................ 29

3.111 Effect of Time on the Reaction of Various ilydrazines with Phenylisocyanate (1.0 ml) at 19 0 . . . • 30

3.IV Effect of Various Concentrations of Phenylisocyanate .................... 30

3.V Effect of Time and Concentration of IJDMH with RCNO at 190 ..................... 31

3.VI Effect of Time and Concentration of 1JDMB with RCNOat39° .................... 31

3.VII Effect of Concentration and Time on UDMH at 190 for 18 H ....................32

3. VIII Effect of Acetic Acid .................33

3.IX Analysis of N2H4/UDMH Admixtures ............33

V

LIST OF TABLES (Con't)

TABLE PAGE

3.X Analysis of MMH/UDMH Admixtures ............ 34

4.1 Various Media for Aldehyde Determination ....... 39

4.11 Effect of Concentration of Acetic Anhydride on Hydrazine ..................... 40

..III Effect of Time on Acetic Anhydride .......... 41

4.IV Effect of Various Isocyanates with Hydrazine in Alcohol Medium .............. 42

4.V Analysis of Various Aldehydes, Anhydrides, Isocyanates and Isothiocyanates ............ 43

5.1 Effect of Isothiocyanates on Various Hydrazines in Alcoholic Medium using O.1N HC1/Propanol ...... 46

5.11 Effect of Isothiocyanate on Hydrazine in Various Solvents using Perchioric Acid in Dioxan as Titrant . . 47

5.111 Effect of Isothiocyanate on Hydrazine in Acetic Acid using 0.1N Perchioric Acid in Acetic Acid as a Titrant ..................... 48

5.IV Effect of Isothiocyanate on Hydrazine in Chlorobenzene and Ethanol using 0.lN Hydrochloric Acid in Propanol as a Titrant ..................... 48

5.V • Effect of Isocyanate in Chlorobenzene an Ethanol using 0.1N Hydrochloric Acid in Propanol as a Titrant . 49

5.VI Effect of Time on the Reaction of Naphthylisothiocyanate and Hydrazine ......... 50

5.VII Analysis of Isocyanate-Isothiocyanate Mixtures . . . . 51

6.1 Height of Precipitate vs Concentration of Hydrazine . . 53

6.11 Colorimetric Reactions of Hydrazines, and Amines with Dinitro Compounds ........... 54

6.111 Reaction of Various Iso and Diisocyanates with Hydrazines .................... 56

vi

SUMMARY

ft

This thesis presents the experimental work involved in developing

new procedures for the determination of hydrazines, their mixtures, and

the use of Hydrazine (N2H4) as an analytical reagent.

This thesis is divided into six sections each of which is complete

in itself. Cross references are made of the tables and equations.

Section I presents the references that pertain to (a) the analysis of

N 2 H 4 by oxidation and basic techniques and (b) the use of N 2 H 4

as

an analytical reagent.

Section II describes the procedures for determination of various

mixtures of N2H4 , monomethyihydrazine (MMH) and 1,1-dimethyihydrazine

(IJDNB). N 2 H 4 forms a precipitate with salicylaldehyde; MM and UDMH

do not. By proper combination of a total iodate titration, N 2 H

4

aldehyde precipitation and an acid-base technique, various mixtures

of all three hydrazines can be determined. Section III describes

the procedures for determination of N 9H4 /UDMH and NMH/IJDMH based on

the reaction rates of N 2 H 4 and MMII with isocyanates. Both N

2 H 4

and MMII react immediately; IJDMH does not. This selective reaction

coupled with an acid-base titration allows the mixtures to be deter-

mined. Section IV presents the procedures for determination of various

organic functional groups i.e. aldehydes, anhydrides, isocyanates and

isothiocyanates based on their reaction with hydrazine. Excess N 2 H

4

vii

is added to the functional groups and allowed to react. The excess

N 2 H 4

is titrated with perchioric acid. By use of this technique many

compounds, belonging to the above functional groups, can be determined.

Section V presents the procedures for the determination of phenyl

isocyanate and phenyl isothiocyanate mixtures. Other aromatic iso

and isothiocyanates can be determined also. Both iso and isothio-

cyanate compounds react with N2 H4

in alcoholic medium using alcoholic

hydrochloric acid as a titrant. Only the isocyanate reacts with N 2 H

4

in acetic acid using perchloric acid in dioxan as a titrant. By

proper selection of aliquots, medium and titrants, the iso and

isothiocyanate mixtures can be determined. Section VI presents several

potential procedures for hydrazine analysis and the use of N2 H4

as

an analytical reagent. (a) Both hydrazine and certain aldehyde form

precipitates with each other and hence can be determined gravimetrically

by proper selection of condition.(b) The reaction of hydrazines and

amines with certain dinitro compounds, produce highly colored com-

pounds. The colors are more pronounced with N 21-14 and MMII than with

the amines. As a result, determination of either hydrazine in the

presence of amine is feasible. (c) Also, iso and diisocyanates

react rapidly with N2 H4 * Based on the reaction rates, many combina-

tions of iso, isothio and diisocyanates (aromatic and aliphatic)

could be determined.

viii

SECTION I

INTRODUCTION

Hydrazine, monomethylhydrazine, and 1,1-dimethylhydrazine are

rocket fuels. Occassionally, they are blended in certain proportions

to obtain certain properties superior to those of the individual

fuels. The higher specific impulse of hydrazine (N2H4 ) and the lower

freezing point of 1,i-dimethylhydrazine (UDMH) are present in mixtures

of these fuels. The neat hydrazines find application as monopropellants

for small rocket engines. Hydrazines and their derivatives are also

used for plant growth retardants, drug manufacture and fertilizers.

Hence, the wide interest in hydrazine chemistry.

The subject of hydrazine chemistry has been amply covered by

Audrieth and Ogg's, "The Chemistry of Hydrazine" (Wiley, 1951), Clarks',

"Hydrazine" (Mathieson Chemical Corporation, 1953), Reed's Monograph,

"Hydrazine" (Royal Institute of Chemistry, 1957) and Malone's Monograph,

"The Determination of the Hydrazino-Hydrazide Groups" (Pergamon, 1970).

The analytical methods for the determination of hydrazine are numerous

and mixtures of hydrazine compounds, with each other and with other

compounds such as amines and hydroxylamines are presented in detail

in Chapter 8 of Malone's Monograph.

The methods presented herein supplements the latter referenced

work and pertain to the determination of N 2 H 4

in mixtures with

substituted hydrazines - namely monomethyihydrazine (MMH) and (UDMH)

and (b) to the use of N 2 H 4 as an analytical reagent to determine various

1

functional groups such as aldehydes, anhydrides, isocyanates, isothio-

cyanates and mixtures of isocyanates with isothiocyanates.

The methods are simple, require a minimum of equipment, are

relatively accurate and demonstrate quite satisfactorily both the

simplicity of analyzing the hydrazine mixtures and the versatility of

using N 2 H 4

as an analytical reagent.

Here the methods are based on two important chemical properties

of N2 H4- its reducing ability with oxidants and its basicity in

non aqueous media.

Previous methods for the analysis of N 2 H 4 based on its reducing

properties is summarized in Table 1.1.

TABLE 1.1

METHOD FOR HYDRAZINE DETERMINATION (OXIDATION)

Author

Koithoff

Kurtenacher & Wagner

Szebelledy & Madis

Sant and Mukherji

Yamamura & Sikes

Barakat & Shaker

Benrath & Ruland

Singh & Siefker

Singh & Singh

Komarowsky

Method Rpfprpnrp

Bromate in HC1 1

Bromate in H2 SO4 2

.Bromate phosphomolyhic acid 3

Bromate amperometrically 4

Bromate 5

N-Bromosuccinimjde 6

Ceric sulfate 7

Iodine Monochioride 8

Diethylenetetraa ammonium 9 Ceric sulfate

Chioramine T 10

2

TABLE 1.1 (Continued)

Author Method

Stolle lodometric

Rupp lodometric

Singh & Rehman Chioratnine T

Singh & Sood Chioramine T

Clark & Smith Chloramine T

Paul & Singh Chioramine B

Singh & Sood Chioramine B

Browne & Shetterly Copper oxide - Fehlings Soin

Bray & Cuy Copper oxide - Fehlings Soin

Browne & Shetterly Copper sulfate

Browne & Shetterly Copper sulfate

Browne & Shetterly Dichromate

Bray & Cuy Dichromate

Erdey Potassium Ferricyanide - Ascorbic acid

Dernback & Mehlig Alkaline Potassium Ferricyanide

Bray & Cuy Hypochiorous acid

Sant Ferricyanide - Zinc sulfate

Bray & Cuy Iodine

McBride & Kruse Iodine

Curtis & Shulz Iodine

Rowe & Audrieth Iodine

Browne & Shetterly Iodine

Stolle Iodine

Bray & Cuy Iodine

Gilbert Iodine

Koithoff Iodine

Penneman & Audrieth Iodine

Miller & Furman Iodate (UDNH)

Rimini Iodate

L.

- -

11

12

13

14

15

16

17

18

19

18

18

18

19

20

21

19

22

19

23

24

25

18

11

19

26

1

27

28

29

3


Author Method Reference

McBride & Kruse Iodate (UDNH) 23

Hale & Redfield Iodate / 30

Browne & Shetterly Iodate 18

Kurtenacher & Kubina Iodate 31

Maselli Iodate 32

Jamieson Iodate 33

Kolthoff Iodate 1

Lang Iodine Cyanide 34

Horvorka Mercuric Perchlorate 35

Singh & Ilahi Iodate 36

Smith & Wilcox Iodate 37

McBride, Henry & Skolnik Iodate 38

Olin Mathieson Personnel Iodate 39

Singh & Singh Periodate 40

Singh & Singh Periodate - Iodine Bromide 41

Singh & Singh Periodate - Iodine Cyanide 42

Peterson Permanganate 43

Sabanajeff Permanganate 44

Browne & Shetterly Permanganate 18, 45

Bray & Cuy Permanganate 19

Koithoff Permanganate 1

Roberto & Roncalli Permanganate 46

Medri Permanganate 47

Penneman & Audrieth Permanganate 25

Houpt Permanganate 48

Issa & Issa Permanganate (Thallium & Telluric Acid) 49

Suseela Selenious Acid 50

Berka & Busev Thalluim 51

Hoffman & Kuspert Vanadic Acid 52

Browne & Shetterly Vanadic Acid 18

Bray & Cuy Vanadic Acid 19

Singh & Singh Sodium Metavanidate 53

OXIDATION OF HYDRAZINES

Rimini (29)

found that the reaction between hydrazine sulfate and

potassium iodate (Kb 3 ) could be expressed by the equation:

5 N 2 H • HSO4 + 4 K103 -- 5 N2 + 12 H 2 0 + 2 K2 SO4 (1.1)

+ 3 HSO + 4 I

Jannasch and Jahn (54) stated that K10 3 solutions were easily re-

duced by hydrazine sulfate. Browne and Shetterly 8 experimented with

the Kb 3 - hydrazine sulfate reaction to determine the quantity of

ammonia and hydrazine acid formed. No hydrazoic acid was formed.

Hale and Redfield (29) conducted a series of experiments to prove that

the complete oxidation of N 2 H 4 was expressed as:

N 2 H 4 + 2 0 -* N2 + 2 1120 (1.2)

Kolthoff evaluated the Andrews-Jamieson (33) iodate method. In

the presence of HC1, the Kb 3 reacts with hydrazine according to the

equation:

N 2 H 4 + Kb 3 + HC1 - KC1 + Id + N2 + 3 H 2 0 (1.3)

Koithoff stated that carbon tetrachloride could be used in

place of chloroform as a visual indicator.

Penneinan and Audrieth 27 combined the oxidation titration of N 2 H 4

with an acidimetric titration method for rapid analysis of both

hydrazine and ammonia. They stated that the normality of HC1 should

be maintained within certain limits, preferably between 3 and 5 to

allow the formation of free iodine. Perineman and Audrieth 27 also

evaluated the use of Amaranth and Brilliant Ponceaux 5R for visual

indicators. McBride, et al (39) thoroughly studied the titrimetric

5

analysis of hydrazine sulfate using Kb 3 . They verified the work of

Penneman and Audrieth(27) concerning the HC1 normality limits. They

also oxidized N 2 H 4

quantitatively with Kb 3 to nitrogen in 0.5 to

2.ON sulfuric acid. The net reaction formulated by McBride et al (38)

is:

5 NH5 + 4 I0 - 5 N 2 + 2 12 + 11 H20 + H30+ (1.4)

McBride and Kruse (23) used a potentiometric end-point method to deter-

mine UDMH. They controlled the acidity, temperature, sample size and

concentration of UDMH. They found that the temperature had to be

maintained at -5 1 to +50 and the titration had to be completed in

10 min or side reactions would occur. A calomel electrode in a salt

bridge was required because of the low temperature involved.

2 (CH 3)2NNH + Kb 3 + 2 HC1 -- KC1 + Id + 2 1120 + (CH 3)2NN = NN (CH 3)2

(1.5)

Olin Mathieson (39) personnel adopted the potentiometric

titration method using Kb 3 to the determine monomethyihydrazine.

The reaction occurs according to equation:

CH3N2H4 + K103 + 2 HC1 -- KC1 + Id + CH 3OH + N2 + 2 1120 (1.6)

Singh and Ilahi 36 estimated hydrazine sulfate using potassium

iodate in the presence of hydrochloric acid by potentiometric titra-

tion. While Smith and Wilcox (37) used dyestuff internal indicators

for the same reaction in hydrochloric acid.

Jamieson (33) determined hydrazine salts with potassium iodate in

the presence of hydrochloric acid using chloroform. The Iodine formed

appeared in the chloroform layer. Continued titration of the iodine

with iodate formed iodine monochioride which was insoluble in the

chloroform layer.

Miller and Furman (28) showed that oxidation of hydrazine with

potassium iodate in the presence of mercuric salts resulted in direct

reduction of iodate to iodide. They detected the end-point potentio-

metrically. In Section 2, iodate is used to determine mixtures of hydra-

zines. The Jamieson (33) method for hydrazine and the modifications of

(23) McBride et al for UDMH are incorporated into a single method.

TABLE 1.11

METHOD FOR HYDRAZINE DETERMINATION (BASICITY)

L_.

Author

Gilbert

Penneman & Audrieth

Weed

Malone

Burns & Lawler

Serencha

Malone & Biggers

Malone

Dwiggins & Larrich

Malone & Barron

Malone & Barron

Method

Hydrochloric and Sulfuric Acids

Hydrochloric and Sulfuric Acids

Perchioric Acid

Perchioric Acid (Salicylaldehyde)

Perchioric Acid (Photometric)

Perchioric Acid (MNH - Sodium Acetate)

Perchioric (Acetic Anhydride)

Perchioric Acid (Salicylaldehyde)

Nitric Acid - Sodium Hydroxide

Hydrochloric Acid (Salicylaldehyde)

Hydrochloric and Perchioric Acids

Reference

26

27

55

56

59

59

59

60

61

62

63

BASICITY OF HYDRAZINES

Methods for the determination of hydrazine based on Its basicity

are shown in Table 1.11.

Perchioric acid has been the most widely used acid for the deter-

7 p

inination of the basicity of hydrazines. Conant and Hall (64) were the

first to use perchioric acid to titrate organic amines in acetic

acid. Since then, many papers have been written on the subject of

non aqueous titrations. Of interest here are those of Fritz and

(65) (66) Keen , and Riddick . By applying the reaction of salicylaldehyde

with primary amines in a non aqueous media, .Wagner et al(67) dis tin-

quished primary amines from secondary amines. Critchfield and Johnson (68)

modified their procedure using salicylaldehyde to determine primary,

secondary and tertiary amines.

Malone (60) adopted the aldehyde technique for determining mixtures

of aniline, N 2 H 4 and furfuryl alcohol.

The analytical methods presented herein are primarily conducted

in non aqueous media using either acetic acid or dioxan. Acetonitrile

(spectrograde) serves as a good medium also. For the most part

visual indicators have been used i.e. quinaldine red, ethyl red and

crystal violet. Glass-calomel electrode systems work satisfactorily.

Also, perchioric acid in dioxan or acetic acid is used as the titrant.

TABLE 1.111

METHODS FOR HYDRAZINE USE AS AN ANALYTICAL REAGENT


Siggia & Stahl Aldehydes 69

Riegler Alkali (Gasometric) 70

Schiotter Bromate 71

Riegler Iodide (Gasometric) 72

I



Ebler Mercuric Chloride (Gasometric) 73

Van Slyke Iodates 74

Strecker & Shartow Selenium Dioxide 75

Lang Selenium Dioxide 34

Singh & Sood Selenium Dioxide 17

Panwar Permanganate, Cerium IV, Dichromate 76, 77 Carbonyls, Mercury, Peroxides et al

Stolle Iodine 11

Peterson Permanganate 43

Koithoff Permanganate 1

Shilling & Hunter Levulinic Acid 78

HYDRAZINE AS AN ANALYTICAL REAGENT

The methods for determining various compounds using hydrazines as

analytical reagents are shown in Table 1.111.

Carbonyls

The most widely used methods for determining aldehydes (carbonyl

compounds) are based upon their reaction with hydroxylamine to form the

corresponding oxime. The amount of hydroxylamine consumed is a

measure of the carbonyl compound present in the sample and is measured

by titration of the excess base with standard acid. Many modifications

of this method are listed in the literature. Ruch developed a method

for determining aldehydes in the presence of ketones using potassium

mercuric iodide. The aldehydes are oxidized to the corresponding

i

acid, effecting a quantitative liberation of mercury. The reduced

mercury is maintained in a finely divided state by using an agar

solution as a protective colloid. The reaction mixture is acidified

and the mercury is reacted with a measured excess of iodine. This

excess is determined using sodium thiosulfate. Hydrazines and

hydrazine derivatives have found wide use for determining carbonyl

compounds. Siggia et al (68) presented an acid-base method fcr

determining aldehydes by their reaction with 1,1-dimethyihydrazine.

An excess of the hydrazine reagent was added to the sample and after

the reaction was complete, the excess was titrated with standard acid.

Many workers used 2,4-dinitrophenyihydrazine (2,4 DNP) as a reagent

to determine qualitatively and quantitatively carbonyl compounds as

(81) hydrazones. Clift (80) determined ketonic acids; Houghton estimated

benzaldehyde; Iddles et al (82) extended the use of 2,4 DNP as a

quantitative reagent; Schoniger 8 applied 2,4 DNP to micro deter-

minations and Monty , Anet , Jart et al used chromato-

graphic techniques. Panwar et al (76) used hydrazine reagent

to determine carbonyl as well as many other compounds. Hydrazine

was used in iodometric titrations.

Here the author is using hydrazine similar to Siggia' 68 to

determine aldehydes. An excess hydrazine is added to the aldehyde

in acetic acid medium, after the reaction is complete, the excess

hydrazine is titrated with standard perchioric acid.

10

Anhydrides

The anhydrides of carboxylic acids are quite reactive, as a result,

they can be determined readily, usually with a compound containing an

active hydrogen group. The principal methods for analysis of anhydrides

depend upon the reaction of the anhydride with amine to form the

(87)

corresponding amide. Siggia et al developed a method using aniline

which reacts with most anhydrides to form one equivalent of carboxylic

acid and an equivalent of amide:

0 0 .0 II 11 II

C6H5NH2 + (RC) 20 -- RC - NHC 6H5 + RC - OH (1.7)

The carboxylic acid formed in this reaction and any free acid present

in the anhydride, can be determined by titration with standard sodium

hydroxide using phenolphthalein indicator according to the methods

of Radcliffe et al(88) and Smith et al (89)The difference between

the total acidity obtained by direct titration in the presence of

pyridine and the acidity after the aniline reaction is a measure of

the anhydride content of the sample.

Morpholine reacts with anhydrides to form amides and the corresponding

carboxylic acid according to the equation

0 0 0 II ,- II II

OJH + (RC) 2 0 - OSN -- C - R + RCOH (1.8)

(90) In this method by Johnson et al , morpholine is reacted with

anhydrides in methanol medium. The amount of morpholine used is

determined by titration with standard methanolic hydrochloric acid using

methyl yellow - methylene blue indicator. A third method for analyzing

11

anhydride and acid mixtures is that of Critchfield et al (67) which is

based on the reaction of an excess morpholine with the anhydride in

acetonitrile medium. Again, the reaction products are the same as

shown in equation 1.2. The acidity is determined using standard

sodium hydroxide using thymolphthalein indicator. Carbon disulfide is

added at the equivalance point and converts the morpholine to the

corresponding dithiocarbamic acid. Siggia et a1 9 I also developed

a method for determining anhydride in acetone using tertiary amines

such as tri-n-propylamine and N-ethyl piperidine.

In these procedures all of the anhydride is reacted with amines

to form amides. In the method introduced here, the author reacted

anhydrides with hydrazines to form hydrazides. The excess hydrazine is

titrated with standard perchioric acid. Since acetic acid can be

used as a solvent, the previous difficulty of determining anhydrides

in the presence of acids is overcome.

Isocyanate and Isothiocyanates

Isocyanates and isothiocyanates have been determined by a variety

of methods. Siggia et al (97) reacted primary amines with isocyanates

and isothiocyanates to form the corresponding ureas and thioureas.

A measured excess of butylamine in dioxan is reacted with the sample.

After the reaction is complete, the excess butylamine is titrated in

the presence of weakly basic ureas with standard sulfuric acid using

methyl red indicator. Beazley 93 used dimethylformamide as a medium

for dicyclohexylamine to determine allyl, n-butyl, cyclohexyl, phenyl

and toluene - 2-4-diisocyanates. Previously, other analysts

12

(94) (95) (96) (97) (98) Stagg , Siefken , Williamson , Navyazhskaya , Kubitz

Strongin et al 99 , Mikl °° , and Ryaakina and a1ika 0 used

n-butylamine, dibutylamine, diethylamine, diisobutylamine, and

piperidine as amine reagents and back titrated the excess amine with

hydrochloric acid.

Grehov et a1 02 determined isocyanates using benzoylhydrazide.

The reaction was conducted in benzene solution for 25-30 mm. at

50-600C, HCl and HBr were added and the excess hydrazide was back

titrated potentiometrically with sodium nitrite.

Several IR and gas chromatographic methods have been developed

to determine the isocyanate group. Using IR, Lord (103) and Finkel

et al(104) quantitatively differentiated toluene -2,4 diisocyanate

and toluene -2,6 diisocyanate at 780 and 810 cm -1 . Burns (105)

Greth et ai06), Zhokhova et al(107) and Kitukhina et al 08

determined the isocyanate group in polyurethane foams at 2000-2950

-i (109) (110) cm . Nebaver et al , Strepikheev et al , Hanneman and

(111) (112) (113) Robinson , Nikeryasova and Litovchenko and Ruth all

usedgas chromatographic techniques to determine aliphatic and aromatic

isocyanates.

Isothiocyanates were determined by Kjaer et al(114), Nagashima and

Nakagawa W5), Appelqvist and Josef sson 116 and Langer and

Gschevendtova 7 using IR and measuring the absorbances at 235-260 nm.

Ammoniacal silver reagent was used to. detect isothiocyanate by gravi-

metric and titrimetric techniques. Basically, the isothiocyanate is

13

reacted with ammonium hydroxide for several hours then treated with

silver nitrate, after a certain time the silver sulfide is precipitated

and weighed. The method of Dieterich (118)

developed in 1891 was

subsequently modified by many others. Roth (119) , Karten and Ma (120)

and Vinson (121)

used Di-n-butylamine and n-butylamine to determine

isothiocyanates.

Here an excess hydrazine is reacted with either the isocyanates

and isothiocyanates. After the reaction is complete, the excess

hydrazine is titrated with perchloric acid.

The following sections are complete in themselves and describe

a method or methods for determining specific compounds or groups of

compounds using hydrazines or possible new methods for analyzing hydra-

zine or hydrazines in the presence of amines.

14

SECTION 2

DETERMINATION OF MIXTURES OF HYDRAZINE, MONOMETHYLHYDRAZINE AND

1, l-DIMETHYLHYDRAZINE

Mixtures of hydrazine (N 2H4 ) and monomethyihydrazine (MMH) were

determined by an oxidation-aldehyde method based on the selective re-

action of N 2 H 4 with salicylaldenyde and subsequent titration of MMH with

potassium iodate. Two aliquots were used, (a) for determining total

hydrazines, (b) for determining MMH, by titration with potassium

iodate. The N2H4 , precipitated as salicylidine azine, was determined

by difference.

In previous papers (56), (60), (63), Malone presented non-aqueous

methods for the determination of N 2 H 4 in admixtures with 1,1-dimethyl-

hydrazine (IJDMH) and secondary amines. These methods were based on

the acid-base titration of the UDMH and amines, using perchioric acid

as titrant, after the N 2 H 4 had been rendered neutral with either

salicylaldehyde or acetic anhydride (59). Clark and Smith (15) developed

a method for determining admixtures of N 2 H 4 and MMII by a differential

oxidation method. One sample aliquot was treated with excess chlorainine-T

and a second aliquot was treated with excess sodium hypochiorite in

the presence of potassium bromide and a phosphate buffer. The unreacted

oxidant was determined by back-titration with sodium thiosulfate.

Both hydrazines involved a four electron change with chloramine-T.

With sodium hypochiorite, N 2 H 4 involved a four electron change and

MMII an eight electron change. For this method, three standard reagents,

15

together with several other additives and buffer were required.

Serencha et al (58) extended Malone 's method (60) using salicylaldehyde

in the presence of excess perchioric acid to determine admixtures of

N2H4 /MMR. The excess perchloric acid was back-titrated with sodium

acetate. This non-aqueous acid-base method was simple and effective

and required the use of two standard titrants. Two gas chromatographic

techniques presented by Jones 22 and by Dee et al (123)

for -letermining

admixtures of N2H4/NNH and UDMH/MMH/N2H4 respectively are satisfactory,

but require good technique and a sound knowledge of chromatography.

The following work describes a simple, rapid, oxidation-aldehyde

method using the Jamieson (33) potassium iodate method with salicylaldehyde

for determining admixtures of N2H4 /MMH and N2H4 /UDMH. This procedure

can also be combined with the non-aqueous titration method described

(59) previously to give a method for the analysis of mixtures of

NNH and UDNH; effective removal of the hydrazine and MMH as the corres-

ponding hydrazides by adding acetic anhydride allows the UDMH present to

be determined in dioxan as solvent with perchloric acid in acetic acid

as titrant.

DV A ("PT11C

In acid medium, salicylaldehyde should react with N2 H4-% MMII and

UDNH to form Salicylidene Azine

0 H H viz. (-C-H

N2H4 + 2E,jIOH 1,j1 OH 11o1>.J-l- 2 H20 (2.1)

and Salicylidenemethyihydrazone

16

H viz. I - H C

+ O:OH

L)-OH

H C- 3 /i LV-jy. CH

Hfi I II (.0

OH HO,) (2.2)

and SalicylidenedimethyihydraZOfle

H H

cIr OH C=O •'-.

OH 2

H3C

CH ± 2H0 (2.3) N-N-H2 + --b,-

Under the conditions of this experiment, however, only the N 2 H 4

reacts completely. The salicylidinementyihydrazine and salicyledinedi-

methyihydrazone do not form.

EXPERIMENTAL

Preparation of Sample (Method A). Pipette 1.5 ml of the hydrazine

mixture into a tared 50 ml volumetric flask containing 20 ml of distilled

water and 10 ml of acetic acid. Cool to room temperature and weigh to

the nearest 0.1 mg, obtaining the sample weight by difference. Dilute

to the mark with distilled water and mix thoroughly.

Determination of Total Hydrazine and Monomethylhydrazine (Method A).

Pipette 5 ml aliquot of the hydrazine mixture into a 500 ml iodine

flask containing 50 ml of 6N. Add 25 ml of concentrated 12N hydrochloric

acid and 20 ml of chloroform. Titrate rapidly with 0.lM postassium

iodate 33 , while shaking, Until the dark brown solutioü lightens.

Then, add the potassium iodate dropwise until the liberated iodine in

the chloroform layer changes from purple to colorless and the solution

becomes yellow from the iodine monochloride formed. This gives titre "A 2 .

17

Determination of Monomethyihydrazine. Pipette 5 ml aliquot of the

hydrazine mixture into a 400 ml beaker containing 50 ml 6N hydrochloric

acid. Add 10 ml of salicylaldehyde in acetic acid solution (10% v/v).

Allow the yellow precipitate of salicylidine azine to set for 15 mm.

Filter through Whatman No. 40 filter paper on a Buchner funnel. Wash

the precipitate several times with distilled water and transfer the

filtrate to a 500 ml iodine flask with several rinsings of distilled

water. Add 25 ml of 12N hydrochloric acid and 20 ml of chloroform.

Titrate rapidly with 0.lN potassium iodate to the disappearance of

iodine in the manner described above. This gives titre "B 21.1-

Analyses of Mixtures of Hydrazine and 1,1-Dimethyihydrazine.

(Method B) Preparation of sample. Use the procedure outlined in

Method A. Determination of N 2 H 4 + UDMH. Use the procedure detailed

in Method A for N 2114 + NHH, but ensure that the temperature lies within

the range _100 to +100 by cooling in a carbon dioxide-acetone mixture.

The titration can also be carried out potentiometrically with a

platinum-calomel electrode system. This gives titre ttBtt.

Determination of l,l-Dimetriylhydrazine. Use the procedure detailed

in Method A for monomethylhydrazine, but maintain the temperature within

the range -10 to +10° . The potentiometric end-point lies between 0.67

and 0.70 V. To minimize side-reactions, complete the titration (23)

within 3-5 mm. This gives titre "B 2 tt .

18

CALCULATIONS

N2H4 +K103 +2 MCi = KC1+ IC1+N2 +

CH 3—NHNU2 +K103 +2HC1-KC1+ICl+CH3OFI+N2 +2H20

2 (CH 3 ) 2N-NH2 + Kb 3 + 2 MCi = (CH 3) 2 N-N = N -N(CH3 ) 2 + KC1+IC1+3H20

Let the Kb 3 molarity = M. Then:

3.20M [(A1 - A 2 ) or (B 1 - B2 )] x,10

% hydrazine sample wt. (g)

4.60MA2 x 10 %MMH=

sample wt. (g)

12.02M B 2 x 10 % UDNH = _______________________

sample wt. (g)

Analyses of Mixtures of three Hydrazines, Monomethylhydrazine, and

1,1-Dime thyihydrazine.

Preparation of Sample (Method C). By pipette, place 0.8 ml of

the mixture of hydrazines into a tared 50 ml standard flask containing

20 ml of acetic acid. Weigh to 0.1 mg, by difference. Dilute to

the mark with distilled water, and mix carefully.

Determination of Hydrazine + Monomethyihydrazine + 1,1-Dimethyl-

hydrazine. By pipette, add an aliquot (10 ml) of the hydrazine

mixture to a 500 ml iodine flask containing 50 ml of 6N hydrochloric

acid. Proceed exactly as described in Method A for the determination

of hydrazine + monomethylhydrazine with potassium iodate. This

gives titre "C 1".

/

19

Determination of Monomethyihydrazine + 1,1-Dimethyihydrazine.

By pipette, add an aliquot (10 ml) of the mixture of hydrazines to

a 400-ml beaker containing 50 ml of 6 N hydrochloric acid. Add

10 ml of a solution of salicyladehyde in acetic acid (10%, v/v)

and complete the determination of MMH + UDMH as described in Method

A above for the determination of MNH alone. This gives titre "C 2 t1 .

Determination of 1,1-Dimethyihydrazine. By pipette, add an

aliquot (2 ml) of the mixture of hydrazines to a 100-ml beaker

containing 20 ml of dioxane. Add 2 ml of acetic anhydride; both

the hydrazine and monomethyihydrazine react to give hydrazides.

Leave the reaction mixture for 30 mm, and then titrate with 0.1N

perchloric acid in acetic acid; conduct a blank determination

using the reagents only. The difference gives titre

CALCULATIONS

Let the Kb 3 molarity = N, and the HC10 4 normality = N. Then:

% NH4 M(C1 - c2) x 5 -

3.201 sample wt. (g) - X

%UDMII NC x25 -= 3 =Y

6.01 sample wt. (g)

MMH = 100 - 4.60[MC 1 - X + x 5 21

sample wt. (g)

20


Fifteen aldehydes were investigated for their selective

precipitation with N 2 H 4 and MMII. UDNH was not investigated. Table 2.1

shows this reactivity as measured by the amount of 0.1 M potassium

iodate used. The reactions were conducted for thirty minutes at

ambient temperature using 5 ml of each hydrazine (1.5 ml N2 H4

Ln 50 ml).

TABLE 2.1

REACTIVITY OF VARIOUS ALDEHYDES WITH N 2 H 4 AND MMII

Ml Kb 3 Ml Kb 3

with N 2114 with MMII

Benzaldehyde 12.0 13.9

Furfuraldehyde 0.0 --

l-Naphthaldehyde 31.O 14.0

4-Hydroxybenzaldehyde 25.5 14.0

3-Hydroxybenzaldehyde 30.5 14.4

Salicylaldehyde 0.0 14.0

Veratraldehyde 0.0 13.8

Anisaldehyde 0.0 13.7

Vanillin 0.0 13.8

2-Ethyihexanal '30.0 14.0


Ml Kb 3 Ml KI03

with N.)H, with MMH

3-Nitrobenzaldehyde 17.0 , 14.0

4-Dime thy laminob enzaldehyde 30.0 13.9

Piperonaldehyde 22.0 14.0

Cinnamaldehyde 0.0 0.0

Crotonaldehyde 0.0 0.0

Of these aldehydes, both cinnamaldehyde and crotonaldehyde, be-

cause of their double bonds, reduced the iodine from the chloroform layer

during the potassium iodate-hydrazine reaction.

Vanillin, veratraldehyde and anisaldehyde all formed precipitates

with N 2 H 4 but produced a yellow-orange to orange coloration in the

chloroform layer. As a result, these aldehydes interfered with the desired

colorless endpoint of the titration after the purple iodine color was

removed. These aldehydes were not purified for this experiment. For

salicylaldehyde, the colorless endpoint was easy to observe except when

the MMH-salicylaldehyde mixture was heated or when an excess of the

aldehyde was used. Heating the reaction (120 °F) for various times caused

the aldehydes to darken. The effect of time, together with the effect

of excess aldehyde, is shown in Table 2.11.

TABLE 2.11

EFFECT OF TIME, TEMPERATURE AND EXCESS ALDEHYDE ON N 2 H 4 AND NNH

Compound Temp. OF

Time Mm.

Salicylaldehyde ml

Iodate ml

N 2 H

4 75 15 2 0.0

N 2 H 4 120 30 2 0.0

N 2 H

4 120 45 2 0.0

22

Exterimental

N2114 MMH

82.5. 15.9 57.1 41.2 51.9 46.9 30.7 68.3 23.2 76.6 17.6 81.4


Compound Temp. Time Salicylaldehyde Iodate OF Mm. nil ml

MMH 120 20 2 16.7

MMII 120 35 2 16.7

MNH 120 60 2 18.0

MMII 75 -- 0 14.0

MMII 75 15 2 14.5

MMII 75 30 1 13.8

1IMEI 75 50 1 13.7

For optimum results, only 1 ml of the salicylaldehyde was required.

This amount was dissolved in acetic acid prior to reaction with the hydra-

zines and was sufficient for precipitating all of the N 2 H4 .

The method was shown to be quantitative for NMH-salicylaldehyde in

the following manner:

ml MMII ml Kb 3

1.0 2.9

2.5 7.0

5.0 14.0

10.0 28.0

A series of mixtures of N 2 H 4 with MMII were prepared and were

analyzed by Method A. The results obtained are shown in Table 2.111.

TABLE 2.111

ANALYSIS OF N 2 H 4 - MMII MIXTURES

- Theoretical Variation in %

N2 H4 NMH N

-2 H4 MMII

82.5 15.9 0.0 0.0 57.6 41.3 -0.5 -0.1 52.2 46.8 -0.3 +0.1 30.5 68.9 +0.2 -0.6 22.8 77.3 +0.4 -0.7 18.0 81.7 -0.4 -0.3

23

A series of hydrazine with UDMH were prepared and were analyzed by

Method B. The results are shown in Table 2.IV.

Table 1.V shows the results obtained for all three components in

test mixtures by Method C.

The results in Table 2.111 indicate that the accuracy improved as

the hydrazine to N'II1 ratio increased. For greater accuracy, the

precipitate could be filtered directly into the vessel used for the

MMH determination, while the N 2 H 4 could be determined gravimetrically

as the azine. Since the azine is soluble in chloroform, the titration

could be conducted directly without filtering, by adding excess (50 ml)

chloroform. However, the azine colors the chloroform layer yellow.

TABLE 2.IV

ANALYSES OF N 2 H

2 - MMH - UDNH MIXTURES

Found (%) Theoretical (%) Difference (%) N 2 H 4 MMH UDNH N 2 H 4 MMH IJDNH N

2 H 4 NNH UDNH

35.9 32.5 29.8 36.9 31.9 29.1 -0.1 +0.6 +0.7

36.8 30.8 28.9 37.6 30.9 29.3 -0.8 -0.1 -0.4

Alternative analytical procedures for the reactions described

here are possible. For example, in the determinations depending on the

selective precipitation of one of more components, the precipitate

24

could be filtered directly into the vessel used for the determination

of MMH. The % hydrazine could also be determined gravimetrically as

the azine; since this is soluble in chloroform, the titration could

alternatively be conducted directly, without a filtration stage, by

adding excess (50 ml) of chloroform. Unfortunately, the azine gives

a yellow chloroform layer; the author prefers to remove the azine

precipitate by filtration. After this is done, the determination of

NNH and UDNH (in the ternary mixture case) can be conducted potentio-

metrically, provided that the platinum-calomel electrode system is

not coated by the azine nor by excess salicylaldehyde; rapid titration

(* 10 mm) within the temperature range _50 to +50 is necessary to

prevent side reactions from occurring between potassium iodate and

UDMH (23)

The well known disadvantages of methods in which one component

is found by difference apply here to the determination of the monomethyl-

hydrazine present. Ammonia and aniline are common impurities in

commercial hydrazine; nitrosodimethylamine, dimethylamine and other

compounds are found (59) in NNH and UDNH.

25

SECTION 3

AN ACID-BASE-ISOCYANATE METHOD FOR THE ANALYSIS OF ADMIXTURES OF

HYDRAZINE WITH 1, l-DINETHYLHYDRAZINE, AND MONOMETHYLHYDRAZINE WITH

1, l-DIMETHYLHYDRAZINE.

A rapid chemical method based on the differential reaction rate

method of l,l-dimethylhydrazine (UDMH)-hydrazine(N 2H4 ), of mono-

methylhydrzine (MMH)-N 2H4 with e.ther phenylisocyanate or

naphthylisocyanate (RNCO) is described.

In alcoholic solution, with ethanolic hydrochloric acid as

titrant, N2H4 , MNH, and UDMH all react with isocyanates at about the

same rate to form semicarbazides. In anhydrous acetic acid, however,

N 2 H 4 and MMII react rapidly (MMH slightly slower than N 2 H 4 ) with

isocyanates, but UDNH does not react appreciably in less than 2 h

at room temperature.

flfl A flrflrrayfl

In acid medium, phenyl and naphthyl isocyanate react with N 2H4 ,

MMII and UDNH to form seniicarbazide

viz.

N2H4 +RCNO-3N112 . NH CO NH R

(3.1)

viz.

H3C N - NH + RCNO +3 . NH • NH CO Nil R (3.2)

H

26

viz.

HC ' -N - NH + RCNO (CH ),)N NH Co NH R (3.3)

H 3 C-'--- 2 /

Under the conditions of the experiment, only the N 2 H 4 and 1'IMH

react completely. The UDMH reaction rate is very slow.

EXPERIMENTAL

Preparation of sample. By pipette, add the mixture of hydrazines

(0.4 ml) to a tared volumetric flask (50 ml) containing about 30 ml of

anhydrous acetic acid; obtain the sample weight by difference. Make up

to the mark with the acetic acid and mix carefully.

Determination of Total Hydrazines. Add an aliquot (5.00 ml) of the

mixture of hydrazines to a 50 ml beaker containing 20 ml of a mixture of

acetic acid and dioxan (1:1). • Add 4 drops of quinaldine red indicator,

0.2% in acetonitrile. Titrate to a colourless end point with 0.1 N

perchioric acid in dioxan to obtain titre "A". T'itrate a blank for the

reagents and indicator to obtain titre "a".

Determination of 1,1-Dimethylhydrazine. Add an aliquot (5.00 ml)

of the mixture of hydrazines to a 50 ml beaker containing 20 ml of the

acetic acid-dioxan mixture and 1 ml of either naphthylisocyanate or

phenylisocyanate. (Use 2 ml for MMH/UDMH.mixtures). Set aside for

30 min ( white precipitate forms). Add 4-drops of the quinaldine

red indicator, and titrate to a colourless end point to obtain titre "B".

By titrating a blank similarly, obtain titre "b".

27

CALCULATIONS

% N 2 H (ffl) = (A-a) - (B-b) HClO 3.20 (or 4.60) , 10

(sample weight)

% UDNH = (B-b) N HC104 6.01 ' 10

(sample weight)


In alcoholic solution with ethanolic hydrochloric acid as titrant,

N2H4 , MMII and UDNH all react with naphthylisocyanate at approximately

the same rate as shown in Table 3.1.

TABLE 3.1

EFFECT OF ISOCYANATES ON VARIOUS HYDRAZINES IN ALCOHOLIC MEDIUM USING 0.1 N HC1/PROPANOL

Compound Non-Aqueous Additive Titrant HC1/Propanol 1 ml/50 ml Ethanol Solvent *RCNO ml (0.1 N) ml used

1 in]. aliquot

N2114 Ethanol 6.40

N2}14 Ethanol 1.0 0.20

UDMH Ethanol 6.27

UDMH Ethanol 1.0 0.80

EM Ethanol 4.10

MMII Ethanol 1.0 0.02

Indicator was meta Cresol Purple 0.2%/Ethanol

*Naphthylis ocyanate

The various hydrazines were reacted with phenylisocyanate in

both acetic acid and dioxan using 0.1 N HC10 4 in acetic acid as

titrant. Table 3.11 shows that either solvent could be used.

28

TABLE 3.11

COMPARISON OF ACETIC ACID AND DIOXAN AS NON-AQUEOUS SOLVENTS FOR THE ANALYSIS OF HYDRAZINE - IJDMII BY THE ISOCYANATE REACTION

Compound Non-Aqueous Additive Titrant 1 ml/50 ml HAc Solvent 1 ml used 0.1 N HC10 4 /HAc 1 ml aliquot ml used

N H Acetic Acid 8.08 2 4 N 2 H

4 Acetic Acid *RCNO 0.10

UDNH Acetic Acid 6.96

UDNH Acetic Acid RCNO 7.10

NNH Acetic Acid 5.05

NMH Acetic Acid RCNO 0.66

Titrant 0.1 HC104 /Dioxan

ml used

N 2 H 4

Dioxan 8.10

N 2 H 4

Dioxan RCNO 0.30

UDMH Dioxan 7.25

UDME Dioxan RCNO 7.17

MMII Dioxan 5.50

MMH Dioxan RCNO 0.60

Quinaldine Red 0.2% in Acetonitrile was used as indicator.

*Phenyljsocyanate

The effect of time and of the isocyanate concentration on the

reaction is shown in Tables 3.111 and 3.IV at least 0.4 ml of phenyliso-

cyanate and a reaction time of 15 min must be used for the effective 0.04 ml

of hydrazine used here. For MM, however, 2 ml of the isocyanate and

30 min reaction time is required.

29

TABLE 3.111

EFFECT OF TIME ON THE REACTION OF VARIOUS HYDRAZINES WITH -- PHENYLISOCYANATE (1.0 ml) AT 19 0

Time (mm) ml HC10, (0.1 N) For NNH For UDNH used

For N 2 H 4

7.90*

5

0.26

15

0.19

30

0.15

45

0.16

60

0.18

75

0.17

* Without phenylisocyanate

5.00*

7.10*

1.90

7.10

1.19

7.08

1.05

7.09

0.77

7.10

0.70

7.08

0.30

7.05

TABLE 3.IV

EFFECT OF VARIOUS CONCENTRATIONS OF PHENYLISOCYANATE*

Phenyliso- ml HC104 (0.1 - N) For NNH For UDNH

cyanate (ml) used For N 2 H

4

0.0 8.20 5.06 7.05

0.2 3.00 2.05 7.05

0.4 0.17 1.25 7.05

0.6 0.18 0.75 7.05

0.8 0.14 0.80 7.03

1.0 0.21 0.55 7.00

2.0 -- 0.10 7.00

3.0 0.06 --

* 20-40 min allowed for the reactions aj 19 0

The effect of time, temperature and concentration of naphthyliso-

cyanate on UDMH is shown in Table 3.V.

30

TABLE 3.V

EFFECT OF TIME AND CONCENTRATION OF UDNH WITH RCNO AT 19 ° C

Time Compound Non-Aqueous Additive Titrant 1 ml/50 ml HAc Solvent ml RCNO 11C104 /HAc (0.1 N) 1 ml aliquot ml used

15 TJDMH Acetic Acid/Dioxan 0.5 3.50

30 UDNH Acetic Acid/Dioxan 0.5 3.48



15 UDME-I Acetic Acid/Dioxan 1.0 3.50


60 IJDMH Acetic Acid/Dioxan 1.0 3.48

120 UDMH Acetic Acid/Dioxan 1.0 3.48


30 IJDNH Acetic Acid/Dioxan 2.0 3.48



When the temperature was increased to 39 ° C the UDNH reacted with the

RCNO as shown in Table 3.VI and formed a precipitate.

TABLE 3.VI

EFFECT OF TIME AND CONCENTRATION OF UDNH WITH RCNO AT 39 °C

Time Compound Non-Aqueous Additive HC1O A /HAc 1 ml/50 ml HAc Solvent ml RCNO (0.1 N) 1 ml aliquot ml used


30 TJDNH Acetic Acid/Dioxan 1.0 3.25

45 UDNI-I Acetic Acid/Dioxan 1.0 3.49

60 IJDMR Acetic Acid/Dioxan 1.0 3.45

The UDMH was reacted with the RCNO and allowed to remain 18 h

at 19 0C. The results shown in Table 3.VII indicate that the UDNH does

-

31

react. A white precipitate of 1,1-dimethyiphenyl semicarbazide

formed; however, the solution still titrated basic.

TABLE 3.VII

EFFECT OF CONCENTRATION AND TIME ON UDNH WITH RCNO AT 19 0C FOR 18 H.

Compound 1 ml/50 ml HAc 1 ml aliquot

tsJiIi

UDNE

UDMH

UDi

Non-Aqueous Solvent (1 / lv)

Acetic Acid/Dioxan

Acetic Acid/Dioxan

Acetic Acid/Dioxan

Acetic Acid/Dioxan

Additive Titrant ml RCNO HC104 /HAc (0.1 N)

ml used

0.0 3.47

0.5 3.25

1.0 2.75

2.0 2.20

Water affects the analysis of hydrazines with isocyanates by

causing the end point of quinaldine red (red to colourless) to revert

to red. The reason for this is shown in the equations below; hydrolysis

of the isocyanate gives the amine which eventually reacts with sufficient

isocyanate to give a substituted urea derivative.

R . NCO + H2O -* R • Nil CO 2H - R NH + Co2 (3.4)

R NH + R . NCO R NH . CO . NH • R (3.5)

Several tests were conducted to substantiate this. As long as

phenylisocyanate was present with acetic acid regardless of the

solvent or titrant the red colour of quinaldine red returned - Diglyme-

HC104 /HAc, HAc-HCl/ROH, ROH-HC10 4 /HAc, Methyipropionate Acetonitrile

and dioxan. Without acetic acid i.e. dioxan - HC104/dioxan with

isocyanate, quinaldine red remained colourless. On addition of

acetic acid, the solution reverted to red. The time of the indicator

change from colourless to red is shown in Table 3.VIII.

32

TABLE 3.VIII

EFFECT OF ACETIC ACID

Compound Non-Aqueous Acetic Acid RCNO Time 1 ml/50 ml ROH Solvent ml ml mm 1 ml aliquot

N 2 H 4 Djoxan 1.0 0.4 4

N 2 H 4 Dioxan 2.0 0.4 2

N 2 H

4 Dioxan 3.0 0.4 1.5

N 2 H 4 Dioxan 4.0 0.4 C.75

N 2 H 4 Dioxan 5.0 0.4 0.75

Because the end-point was not sharp using a dioxan - HC104/dioxan

system a small amount of acetic acid was added. The red colour

returned immediately. Upon addition of acetic anhydride to the UDMH

acetic acid system prior to the addition of isocyanate, the quinaldine

red remained colourless because the water in the acetic acid was pre-

vented from reacting with the isocyanate. Since acetic anhydride

reacts rapidly with both hydrazine and MMH it would interfere in

the quantitative analysis of these two hydrazines. The molecular

sieve technique developed by Burns (57) was used satisfactorily to

remove the water from acetic acid. Potassium cyanàte, potassium

cyanide, lead thiocyanate, phenyl and methylisothiocyanates gave no

reaction with N2H4 , MtYIH or UDNH in acetic acid media.

TABLE 3.IX

ANALYSIS OF N2H4 /UDMH ADMIXTURES

Experimental (%) Theoretical (%) Variation (%) N 2 H 4 UDNH N

2 H 4 UDMH N 2 H 4 UDNH

82.4 13.9 82.6 14.0 +0.2 +0.1

74.0 23.6 73.4 23.5 -0.6 -0.1

33

TABLE 3.IX (Continued)

Experimental (%) Theoretical (%) Variation (%) N2 H4 IJDNH N2114 UDMH N

2 H4 UDNH

64.7 32.6 65.1 32.2 +0.4 +0.4

60.1 37.6 59.6 37.9 -0.5 +0.3

54.1 44.0 53.6 44.3 -0.5 +0.3

48.9 49.4 48.4 39.6 -0.5 +0.2

42.5 55.8 42.2 56.0 -0.3 +0.2

32.7 66.0 32.0 66.7 -0.7 +0.7

20.2 78.5 19.5 79.0 -0.7 +0.5

TABLE 3.X

ANALYSIS OF NNH/UDNH ADMIXTURES

Experimental (%) Theoretical (%) Variation (%) NMH UDNH MMH UDMH MMH UDI'IH

76.1 23.7 76.8 23.2 +0.7 -0.5

85.6 13.6 85.8 14.2 +0.2 +0.6

11.2 88.7 10.8 89.2 -0.4 +0.5

25.5 74.0 25.8 74.2 +0.3 +0.2

47.0 52.4 47.5 52.4 +0.5 -0.0

51.4 47.5 51.8 47.1 +0.4 -0.4

A series of mixtures of N 2H4 /UDMH and MMEI/IJDNH were prepared for

test analyses; the results are shown in Tables 3.IX and 3.X.

For industrial-grade hydrazines, greater accuracy can be obtained

if the "contaminant titration values" for each of the hydrazines is

known. Malone and Biggers (59) reported contaminant titration values of

0.20, 0.12, and 0.04 ml for N2114 , NNH, and UDNH respectively; these

are corrections for any impurities in N 2 H 4 and MMII which behave

similarly to another hydrazine (UDMH) and vice-versa.

34

SECTION 4

DETERMINATION OF ALDEHYDES, ANHYDRIDES, ISOCYANATES AND ISOTHIO-

CYANATES USING HYDRAZINE REAGENT.

A method is presented for determining aldehydes, anhydride,

isocyanates and isothiocyanate by reaction with hydrazine. An excess

hydrazine reagent is added to a sample, and after the reaction is

complete, the excess is titrated with standard acids. Hydrazine can

be used as a reagent to determine various functional group compounds.

Panwar et al (76) used hydrazine in conjunction with iodine to deter-

mind permanganate, copper sulfate, chlorate, bromate and iodate,

periodate, peroxide, ferricyanide, ferrocyanide and both mercurous

and mercuric mercury. In another paper 7 , they determined carbonyl,

thiourea, semicarbazide, several aldehydes, ascorbic acid and

isonicotinic acid hydrazine. In most cases, the iodine was allowed to

react with the compound being analyzed, then the excess iodine was

back titrated with hydrazine. Siggia et al (68) used l,l-dimethyl-

hydrazine (IJDNH) as a reagent for determining aldehydes. An excess of

UDMH was allowed to react with the aldehydes for 30-60 min then the

excess UDNH was back titrated with alcoholic HC1 in ethylene glycol

solvent.

Dt' A ("PT (K1C'

In dioxan medium, hydrazine reacts to form 1,2-diacetyihydrazine

with acetic anhydride as shown in equation 4.1

35

0

o H - CH

N2H4 + 2

CH - 0 2CH3COOH 1

N - CH 3 (4.1)

CH - C H U

0

and salicylidene azine with salicylaldehyde as shown in equation (2.1).

Hydrazine reacts with isocyanates to form semicarbazides as shown

in equation 3.1; hydrazine reacts with Isothiocyanates to form thio-

senticarbazides as shown in equation 4.2 but only in alcohol medium.

N2114 + RCNS Cs NH . R

(4.2)

EXPERIMENTAL

Preparation of Sample. Add 1.0 ml or 1 gram (dissolve in acetic

acid if solid) of the functional group to be analyzed to a tared

volumetric flask (50 ml) containing about 20 ml of dioxan or acetic

acid. Use chlorobenzene for both isothiocyanates and isocyanates.

Obtain the sample weight by difference. Make up to the mark with the

dioxan or chlorobenzene and mix. carefully.

Determination of Aldehydes, Anhydrides, Isocyanates. Add an

aliquot (5.00 ml) of the desired functional group to a 50 ml beaker

containing 20 ml of dioxan or acetic acid and an aliquot (2.00 ml) of

hydrazine reagent. Add 1 drop of quinaldine red indicator 0.2% in

acetonitrile. Allow to react for 20 mm., then, titrate to a colourless

end-point (yellow end point for aldehyde) with O.lN perchloric acid in

dioxan to obtain titre "B". Titrate a blank for the reagents and

indicator to obtain titre "b". Titrate a 2 ml aliquot of hydrazine

reagent with perchloric acid to a colourless end-point to obtain

titre "A"

Determination of Isothiocyanates. Add an aliquot (5.00 ml) of

the isothiocyanate to a 50 ml beaker containing 20 ml of propanol and

an aliquot (2.00 ml) of the hydrazine reagent. Add 2-3 drops of meta

36

cresol purple 0.2% in ethanol. Allow to react for 20 mm., then,

titrate with O.1N hydrochloric acid in propanol to obtain titre "B".

Titrate a 2 ml aliquot of hydrazine reagent with hydrochloric acid in

propanol. Titrate a blank for the reagents and indicator to obtain

titre "b".

CALCULATIONS

% Functional = A - (B-b) x N HC10 4 x N.W. compound x 100 x 25 Group

sample weight (g) x 1000


A series of experiments were conducted with aldehydes (primarily

salicylaldehyde) to determine the best medium and titrant for analyzing

aldehydes. In Table 4.1 acetic acid was used as the non aqueous

solvent and 0.1 N perchloric acid in acetic acid was used as the titrant.

The results show that the milliliters of hydrazine available for back

titration with perchloric acid is reduced. Using perchloric acid in

propanol and propanol, chlorobenzene, ethylene digol and benzene as

solvents and varying the salicylaldehyde added, the milliliters of

perchioric acid is also reduced. However, the endpoint is difficult

because precipitates are formed. On changing the solvent to acetic

acid and the titrant to 0.1 N perchloric acid in dioxan, the endpoint

becomes sharp and the titration proceeds smoothly. The reaction

time of salicyladehyde with hydrazine was determined as 20-30 mm.

A similar series of experiments was conducted with acetic acid

and hydrazine in various solvents namely, ethyl acetate, dioxan and

acetic acid using 0.1 N perchloric acid in dioxan as a titrant.

37

Tables 4.11 and 4.111 shows the effect of concentration and time on

the anhydride - hydrazine reaction. They also show that the excess

hydrazine added to the anhydride sample is reduced proportionately to the

amount of anhydride added. These experiments were conducted between

10-40 mm. Dioxan gave a sharper endpoint than ethyl acetate and the

anhydride-N2H4 reaction occurred more rapidly in dioxan. Acetic acid

gave as good an endpoint as dioxan. Table 4.111 shows the effect of

time on the anhydride - hydrazine reaction in ethyl acetate using

perchloric acid in dioxan as titrant. A time of 20-25 min is adequate

for the acetic anhydride to react.

38

TABLE 4.1

VARIOUS MEDIA FOR ALDEHYDE DETERMINATION

Compound Non Aqueous 1 ml Aldehyde! Titrant 1m]. N2H4/5() mi/HAc Solvent 50 ml HAc HC1O4 /llAc

aliquot ml aliquot ml' O.1N

ml used

2 Acetic Acid 0 7.65



2 Propanol 2 10.0

2 Ethylene Digol 2 (no color

9.5 change)

2 Chlorobenzene 2 10.0

2 Propanol 2 (yellowish) 9.4

2 Propanol 4 (ppt) 7.5



2 Benzene 2 (ppt) 8.5

• 2 Benzene 4 (EP difficult) 6.2

2 Benzene 6 4.0

HC104/Dioxan



• 2 Acetic Acid 4 6.60

2 Acetic Acid 6 5.0

39

TABLE 4. 11

EFFECT OF CONCENTRATION OF ACETIC ANHYDRIDE ON HYDRAZINE

Time Compound Non Aqueous Additive Titrant mm. 1 ml N2H4/50 ml Solvent Acetic 0.1N HC104/Dioxan

Acetic Acid Anhydride ml used

ml aliquot g.

-- 5 Ethyl Acetate 0 4.8

20 5 Ethyl Acetate 0.25 2.9







-- 5 Ethyl' Acetate 0.50










40 5 Dioxan 0.02 3.0

30 5 Dioxan 0.02 2.95

30 5 Dioxan 0.04 2.75

40 5 Dioxan 0.04 2.40

40 5 Dioxan 0.08 1.90

30 5 Dioxan 0.08 2.1

40

TABLE 4.111

EFFECT OF TIME ON ACETIC ANHYDRIDE

Hydrazine Reaction

Time Compound Non Aqueous Additive mm. i ml N2H4/50 ml Solvent 1 ml AcAn/50 ml

Acetic Acid Ethyl Acetate m

ml aliquot l aliquot

Ti trant O.lN HC104 /Dioxan

ml used

5 Ethyl Acetate 0 4.9

5 5 Ethyl Acetate 2 3.9



20 ' 5 Ethyl Acetate 2 32


30 5 Ethyl Acetate .2 3.2

35, 5 Ethyl Acetate 2 3.3



15 5 Acetic Acid 2 3.3

15 5 Acetic Acid 4 1.2

A series of experiments were conducted with isocyanates and

isothiocyanates to determine the conditions for their analysis. In

Table 4.IV propanol was used as the solvent and hydrochloric acid in

propanol was used as the titrant. As shown both the isocyanate and

isothiocyanate react with hydrazine as indicated by the reduction

in milliliters of the alcoholic HC1. This agrees with the data shown

in Tables 3.1 and 5.1 where ethanol was used as the solvent. However,

to keep the use of hydrazine as an analytical reagent simple, whenever

41

possible, perchioric acid is used as the titrant and dioxan or acetic

acid as the solvent. Isothiocyanates can not be determined in acetic

acid medium using perchioric acid as the titrant. The data to sub-

stantiate this is shown in Tables 5.11 and 5.111.

Selected aldehydes, anhydrides, isocyanates and isothiocyanates

were weighed and analyzed by the method described. The results are

shown in Table 4.V as indicated, aliphatic iso and isothiocyanates can

not be determined under the condition described here. Aromatic

isothiocyanates must be analyzed using alcoholic hydrochloric acid as

a titrant and alcohol as a medium as described.

TABLE 4.IV

EFFECT OF VARIOUS ISOCYANATES WITH HYDRAZINE IN ALCOHOL MEDIUM

Time Compound Non Aqueous Additive 1 ml N2H4/50 ml Solvent 1 ml/50 ml Chlorobenzene Titrant

Propanol 20 ml ml aliquot O.lN HC10 /HAc 4

ml aliquot Cyanate ml used

1 Propanol 1 ml Cychiohexyliso 6.0

1 Propanol 1 ml Cychlohexyliso 5.62

1 Propanol 1 ml Cyclohexyliso 5.62

1 Propanol 1 ml Naphthyliso 5.70

1 Propanol 1 ml Naphthyliso 5.40

1 Propanol 1 ml Phenylisothio 4.50

1 Propanol 1 ml Phenylisothio 4.60



1 Propanol. 4 ml Cyclohexyliso 4.90


1 Propanol 6 ml Cylohexyliso 2.80


42

TABLE 4.V

ANALYSIS OF VARIOUS ALDEHYDES, ANHYDRIDES, ISOCYANATES AND ISOTHIOCYANATES

% Determined By % Determined By Hydrazine Method Other Methods

Artisealdehyde 93.8

Cinnamaldehyde 96.4

Salicylaldehyde 97.6 981b

Crotonaldehyde 92.8

Naphthaldehyde 98. 99 . 31

Heptaldehyde 94.5

Proprionic Anhydride 97.8 98.2 Succinic Anhydride 99.1

Phthalic Anhydride 92.2

Maleic Anhydride 9514

Acetic Anhydride 97.2 991b

Trifluoroacetic Anhydride 95.7

Naphthylisocyanate 98.2 99.3

Phenylisocyanate 97.0

Toluene Diisocyanate 99.1 99.0 c

acyc1ohelisocyanate

aDimeryl Diisocyanated

Naphthylisothiocyanate 98.3

Phenyl Isothiocyanate 99.1 986b

aAllylisothiocyanate

Could not determine under conditions described.

b Chemically Pure

C United Technology Corporation by Di-n butylamine method

d c42H66 (NCO)

43

SECTION 5

THE ANALYSIS OF ISOCYANATE-ISOTHIOCYANATE ADMIXTURES USING HYDRAZINE

A method for the analysis of Isocyanate-Isothiocyanate admixtures

based on their reactions with N 2 H 4 is presented. Both naphthyl

and phenylisocyanates and isothiocyanates react with hydrazines in an

alcoholic medium using alcoholic hydrochloric acid as a titrant. Only

isocyanates react with hydrazines (N 2H4 and MMII not UMDH) in an acetic

acid or dioxan medium using perchloric acid in acetic acid as a titrant.

EXPERIMENTAL

Preparation of Samples. Pipette 0.5 ml of the isocyanate-isothio-?

cyanate mixture into a tared 50 ml volumetric flask containing 20 ml

of chlorobenzene. Weigh to the nearest 0.1 mg, obtaining the sample

weight by difference. Dilute to the mark with chlorobenzene and mix

thoroughly.

Determination of Total Isocyanate-Isothiocyanate Mixture. Pipette

a 5 ml aliquot of the mixture into a 50 ml beaker containing 20 ml of

methanol and 10 ml of (0.3 M) hydrazine *(lO g of hydrazine/acetic acid)

in acetic acid solution. Allow 30 minutes for the reaction to occur.

Titrate the excess hydrazine solution with alcoholic HC1 (0.1 N) either

potentiometrically using a glass-calomel electrode system or visually

using meta cresol purple indicator 0.2% in methanol. Call this value "A"

*When adding hydrazine to acetic acid, be careful to add the hydrazine

slowly as the reaction is exothermic. Cool to room temperature before

diluting.

Determination of Isothiocyanate. Pipette a 5 ml aliquot of the

mixture into a 50 ml beaker containing 20 ml of dioxan and 10 ml of

(0.3 M) hydrazine in acetic acid solution. Allow 30 minutes for the

reaction to occur. Titrate the excess hydrazine solution with perchioric

acid (0.1 N) in acetic acid either potentiometrically using a glass

colomel electrode system or visually using quinaldine red indicator 0.2%

in acetonitrile. Call this value "B". Conduct a titration of the

10 ml of (0.3 N) hydrazine as a blank.

CALCULATIONS

(Ml 1-IC1 for sample) - (ml HC1 for blank) x N HC1 x M.W. x 100 X 10 - A sample wt. (g) x 1000 -

(Ml HC104 for sample) - ml HC10 4 for blank x N HC104 x M.W. x 100 x 10

sample wt. (g) x 1000


Chlorobenzene was used as the sample solvent for both isocyanate and

isothiocyanate because of its inertness with these compounds. Isocyanate

and isothiocyanate were reactive with dioxan, acetic acid, methanol and

ethyl acetate as indicated by the formation of a white precipitate. For

the titration solvent using hydrochloric acid, ethanol was used in preference

to chlorobenzene. For the titration solvent using perchloric acid,

solutions of perchioric acid in acetic acid were used. Using dioxan as the

titration solvent gave sharper end points than using solutions of perchloric

acid in dioxan with acetic acid as the titration solvent. The water content

in all reagents should be reduced as indicated in reference (57) because

of the reactivity of water with isocyanate as shown in equations (3.4) and

(3.5).

As shown in Section 3, Table 3.1, N 2H4 , MMLI and UDMH all react

45

with isocyanate in an ethanol solvent system using HC1 in propanol as a

titrant. This same experiment using isothiocyanate Instead of isocyanate

is shown in Table 5.1. Again all of the hydrazines react as indicated

by the decrease in total ml of 0.1 N BC1 required.

TABLE 5.1

EFFECT OF ISOTHIOCYANATES ON VARIOUS HYDRAZINES IN ALCOHOLIC MEDIUM USING 0.1 N HC1/PROPANOL

Compound Non Aqueous Additive Titrant 1 ml/50 ml ROH Solvent ml RCNS 0.1 N HC1/ROH 1 ml aliquot ml used

N2. H4 Ethanol 5.90

N 2 H

4 Ethanol 1.0 0.13*

UDNH Ethanol 6.10

UDMH Ethanol 1.0 2.50

NMH Ethanol 4.10

MMR Ethanol 1.0 0.02

Indicator m cresol purple 0.2% in Ethanol

*White precipitate formed. Solutions were allowed to react for 45 mm.

Also shown in Section 3, Table 3.11, the hydrazines, except UDNH,

reacted with isocyanates in both acetic acid and dioxan using perchloric

acid in acetic acid as a titrant. A series of experiments were conducted

to determine if N 2 H 4 reacts with isothiocyanate in acetic acid medium

and/or dioxan using perchioric acid in dioxan as a titrant. Table 5.11

shows that the N 2 H 4 was unreactive with isothiocyanate in chlorobenzene

and acetic acid. However, in dioxan evidence of reactivity is indicated

by the slight decrease in (ml) required of 0.1 N HC10 4 /Dioxan.

46

TABLE 5.11

EFFECT OF ISOTHIOCYANATE ON HYDRAZINE IN VARIOUS SOLVENTS USING PERCHLORIC ACID IN DIOXAN AS TITRANT

Compound Non Aqueous Additive Titrant 1 ml/50 ml HAc Solvent -1 ml RCNS/ 0.1 N HC10 4/Dioxan 1 ml aliquot 50 ml Chlorobenzene ml used

ml aliquot

N 2 H 4 Chlorobenzene 0 3.30*

N 2 H 4 Chlorobenzene 1 3.30

N 2 H


N H 2 4 Chlorobenzene 3 3.25

N 2 H


N 2 H 4 Acetic Acid 1 3.30

N 2 H 4 Acetic Acid 2 3.30

Acetic Acid 3 3.30

N 2 H Dioxan 0 3.45

N 2 H 4 Dioxan 1 3.00

N 2 H 4 Dioxan 2 2.82

N 2 H 4 Dioxan 3 2.60

*30 min reaction time

Upon changing the titrant to 0.1 N Perchioric acid in acetic acid

as shown in Table 5.111, there was little evidence of reaction between

N 2 H 4 and isothiocyanate. Because of this, perchioric acid in acetic acid

was adopted as the titrant for the rest of the experiments.

47

TABLE 5.111

EFFECT OF ISOTHIOCYANATE ON HYDRAZINE IN ACETIC ACID USING 0.1 N PERCHLORIC ACID IN ACETIC ACID AS A TITRANT

Compound Non Aqueous Additive Titrant 1 ml/50 ml HAc Solvent RCNS, 0.1 NHCl04/HAc

aliquot ml ml used

1 ml N 2 H 4 Acetic Acid 1 4.20


3 ml N2 H4Acetic Acid 1 12.50


A series of experiments were conducted to compare chlorobenzene

and ethanol solvents for the isothiocyanate-N 2H4 reaction and the

isocyanate-N2H4 reaction using 0.1N HC1 in propanol as titrant. Tables

5.IV and 5.V show that both reactions proceed smoothly in either

chlorobenzene or ethanol.

TABLE 5.IV

EFFECT OF ISOTHIOCYANATE ON HYDRAZINE IN CHLOROBENZENE AND ETHANOL USING 0.1N HYDROCHLORIC ACID IN PROPANOL AS A TITRANT

Compound Non Aqueous Additive Titrant 1 1 nil/50 ml R011 Solvent 1 ml RCNS/ 0.1 N HC1/ROH 1 ml aliquot 50 ml Chlorobenzene ml used

ml aliquot

N 2 H


N 2 H


N 2 H




48

--

TABLE 5.IV (Continued)

Compound Non Aqueous Additive 1 ml/50 ml ROH Solvent 1 nil RCNS/ 1 ml aliquot 50 ml Chlorobenzene

ml aliquot

Ti trant 0.1 N HC1/ROH*

ml used

N 2 H 4

N 2 H

4

N 2 H

4

N 2 H

4

N 2 H

4

*30 min reaction time

Ethanol 0 3.15

Ethanol 1 2.45

Ethanol 2 2.05

Ethanol 3 0.90

Ethanol 4 0.60

TABLE 5.V

EFFECT OF ISOCYANATE ON HYDRAZINE IN C}ILOROBENZENE AND ETHANOL USING 0. iN HYDROCHLORIC ACID IN PROPANOL AS A TITRANT

Compound Non Aqueous Additive Titrant 1 ml/50 ml ROH Solvent RCNO 0.1 N HC1/ROH* 1 ml aliquot ml ml used

O 3.14

1 2.25

2 1.30

3 0.45

4 0.25

0 3.15

1 2.20

2 1.45

3 0.48

4 0.20

N 2 H

4 Chlorobenzene

N H Chlorobenzene 2 4




N H 2 4 Ethanol

•

N 2 H

4 Ethanol

N 2 H 4 Ethanol

N2114 Ethanol

NH Ethanol 2 4

*30 min reaction time 49

The effect of time was observed in a series of experiments

shown in Table 5.VI. Hydrazine and MMII reacted between 30-45 mm

with naphthylisothiocyanate. The UDMH was incompletely reacted

even after 75 min using 0.5 ml of RCNS.

TABLE 5.VI

EFFECT OF TIME ON THE REACTION OF NAPHTHYLISOTHIOCYANATE AND HYDRAZINE

Time Compound Non Aqueous Additive Titrant min 1 nil/50 ml ROH Solvent Naphthylisothiocyanate 0.1 N HC1/ROH

1 ml aliquot ml ml used

15 N 2 H

4 Ethanol 0.5 1.65

30 N 2 H

4 Ethanol 0.5 0.37

45 N 2 H Ethanol 0.5 0.17

60 N 2 H

4 Ethanol 0.5 0.11

75 NH Ethanol 0.5 0.08

15 UDMU Ethanol 0.5 5.0

30 UDNH Ethanol 0.5 3.93

45 IJDNH Ethanol 0.5 3.62

60 UDNH Ethanol 0.5 2.59

75 IJDNH Ethanol 0.5 1.92

0 MMII Ethanol 0.0 4.0



45 .MMH Ethanol 0.5 0.10

60 MMII Ethanol 05 0.10

75 . MMII Ethanol 0.5 0.10

50

Mixtures of phenylisocyanate and phenylisothiocyanate were

prepared and analyzed by the described method. The results are

shown in Table 5.VII.

TABLE 5.VII

ANALYSIS OF ISOCYANATE-ISOTHIOCYANATE MIXTURES

Experimental Theoretical Variation in % RCNO RCNS RCNO RCNS RCNO RCNS

71.0 16.6 71.7 16.1 -0.7 +0.5

63.5 34.1 63.0 34.7 +0.5 -0.6

48.5 49.5 48.1 50.1 +0.4 -0.6

32.0 65.3 32.4 65.0 -0.4 +0.3

24.1 74.4 24.7 73.8 +0.6 +0.6

UR

51

SECTION 6

MISCELLANEOUS STUDIES

Several additional techniques have been investigated and are

discussed here for the determination of hydrazines.

GRAVIMETRIC

As described in Section 2, hydrazine forms a precipitate of

Salicylidene Azine with Salicylaldehyde. The formation of this precipi-

tate lends itself to a gravimetric procedure both for the determination

of hydrazine in the presence of other hydrazines but also for the

determination of several aldehydes - those that form precipitates

such as Verataldehyde, Anisealdehyde, Cinnamaldehyde, Naphthaldehyde,

piperonaldehyde and nitrobenzaldehyde.

PRELIMINARY DATA

A sample of N2H4/TJDMH (5.0 ml) was added to a 100 ml volumetric

flask and diluted to the mark with glacial acetic acid. Approximately

(4.0 ml) of Salicylaldehyde (SA) was added to various aliquots of the

hydrazine mixture in 15 ml centrifuge tubes. After setting for 20

minutes, a yellow precipitate formed. Acetic acid was added to keep

the volume constant. The tubes were centrifuged for 5 min and the

height of the precipitate was recorded. Table 6.1 shows the pre-

liminary results.

52

TABLE 6.1

HEIGHT OF PRECIPITATE VS CONCENTRATION OF HYDRAZINE

ml SA N2114 /UDMH N 2 H 4 Height

ml aliquot g of precipitate ml

4 0.5 0.26 0.40

4 1.0 0.52 0.7 - 0.8

4 1.5 0.78 1.30

4 2.0 1.05 1.5 - 1.6

4 2.5 1.31 1.6 , - 1.8

3.0 1.57 2.0

For a practical gravimetric method the following variables must

be determined: the centrifuge time, the proper ratios of aldehyde

(excess) to hydrazine, proper selection of a solvent (not necessarily

acetic acid) proper order of adding reagents, and the limits of these

variables to prevent packing. The method would be readily applicable

for rapid, field type use.

COLORIMETRIC

Hydrazines, as do primary and secondary amines, diamines and

triamines, form highly colored compounds with dinitro compounds. By

proper selection of solvent, and concentrations of hydrazines, and

amines, mixtures of hydrazines in the presence of amines is possible.

In Table 6.11, only concentrated compounds were used, hence the

intensity of the colors and the reactivity of others producing

reddish-black and brownish-black compounds. It appears that hydrazine

can be determined readily in the presence of primary, secondary and

53

• 6.11. CDWR.DTRIC. REACTIONS 'OP HYDRAZINES, .LND ANES WITH DIbTITRO COO1JNDS DIETTr TriEt

1L UD1IL nBNL2 n1ilR2 DMNR2 TBNH2 NetAn DMAn ETDiNH2 NH2 Tet NH2

2,4DNTo P B YG B B C Y R R BC BC DC

nDNB P RP 0 R R (P1) 0 Y RBr RBR P P P

2,6DNT0 P Bur RBr RBr RBr Pi Y 0 RRr BC DC DC

2,4 DN 0 Y-0 Y Y Y Y Y RBr R3r Y Y Y

ODNB BrC BrG Y Y Y Y C RBr RBr RO 0 Y

ONAn 0 Y0 Y Y Y '1 Y Y y y y y

pNAn YG C C Y Y Y C Y Y C C C

1,4DNOPIP C C C C C C C C C C C C

1 Cl 2,4 DNB RBr CB1 DR Y Y0 Y Y REl RB]. RB1 Rhi Y0

4 Cl 3,5 DNBCN BrBl* B1* BrBl* 0 0 0 Y , RBr RB]. RO 0 0

4C12NTo

2,4 DNAnis B]. GB]. YBr Y Y 0 C 0 0 DR DR 0

' NH 2 2C1NPYR RBr •Y Y Y Y Y C Y Y RBr Y Y

2NH2 3NPY B]. Y Y Y Y Y Y Y Y Y 'I

4NH2 3NHT' R Y Y Y Y Y Y Y Y Y Y Y

1,5 DF 2,4 DNB BrBr R0* 0* Y* Y YG R R Y R* Y

2,4,7 TNBAL GB]. RB]. RB]. RB]. RB]. RB]. C BrB]. BrB1 RB]. RB]. RB].

1,3 DNNAPTH RB]. RP RB]. RB]. RB]. RB]. BrB1 RBr RBr RB]. RB]. RB1

]. Cl 2,4,6 TNB HP Bur DR DR DR R Y BrBl BrB1 HP RP HP

2,4 DNFB PB]. B]. BrB]. RO RO Y Y BrB]. BrB]. BrBl* • RO RO

2,4,7 TN 9 FONE BrB]. BrBl RBr Y Y 0 Y DR DR RY DR R

D Di HAL Benza].dehyde P Purple Pi Pink , *Reacts

T Tri Cl Ch].oro B Blue B]. Black

To Toluene AIS Aniso].e Y Yellow Bur Burgundy • S

B Benzene •

.' Diuiethylamine C Green D Dark

DN Nitri].e Net,An N-ethy]. Aniline C Colorless

NH Amine EtDINH2 Ethylene • Br Brom

NAPH - Naphthaldehyde am • 0 Orange

TriEtTetNH - Triethylone tetrenina • 54

• •. :

tertiary amines. Whereas the diamines, triamines and tetramines

might offer some difficulty because of the deep blues and greens

formed. Determining MMH or UDMH in the presence of the amine

groups could be accomplished using o-dinitrobenzene, p-nitroaniline,

1-chloro-2,4-dinitrobenzene, 4-chloro-3,5-dinitrobenzonitrile,

2 ,4-dinitroanisole and 2,4, 7-trinitrofluorene. Compounds containing

the chioro and fluoro groups reacted readily.

The high coloration of the compounds was dependent on the nitro

groups, nitro < dinitro < trinitro and the number and location of the

amine groups in mono < di < tri < tetramine as expected.

HYDRAZINE AS A REAGENT

As shown in Sections 3 and 5, isocyanate compounds, especially

aromatic isocyanates, react readily with both hydrazine and Monomethyl-

hydrazine respectively.

PRELIMINARY DATA

From the preliminary data, as shown in Table 6.111, Isopropyl

isocyanate reacts very slowly, and Toluene diisocyanate reacts immediately

with hydrazine in dioxan. As a result of the larger difference in

reaction rates, it would be feasible to develop analytical methods

for determining, (1) aromatic isocyanates in the presence of aliphatic

isocyanates, (2) Diisocyanates in the presence of aliphatic isocyanates

and aromatic thioisocyanates and (3) diisocyanates in the presence of

diisocyanates (not verified) depending on the location of the isocyanate

group. Table 6.111 also indicates that the proper selection of a solvent

is critical because of the reactivity of the isocyanates. By changing

55

from dioxan to chlorobenzene, a 2 milliliter difference for the

same time was observed. Also, both acetonitrile and nitrobenzene

reacted with the diisocyanate. Normally, the isocyanate reacts

faster than the isothiocyanate and the diisocyanate would react

faster than the isocyanate.

TABLE 6.111

REACTION OF VARIOUS ISO AND DIISOCYANATES WITH HYDRAZ.NE

'ime Compound Solvent Additive Titrant tin. 1 ml N2H,/50 ml HAc 1 ml Isocyanate/ 0.1N HC104 /Dioxan

ml aliquot 50 ml Chlorobenzene ml used ml aliquot

4 Dioxan 0 9.3 20 4 Dioxan 2 ml TDI 6.4 15 4 Dioxan 2 ml TDI 6.7 20 4 Dioxan 4 ml IPI 9.1 20 4 Dioxan 4 ml IPI + 2 ml TDI 6.4 25 4 Dioxan 4 ml IPDI + 2 ml TDI 5.9 5 4 Dioxan 4 ml NAPI + 2 ml TDI 4.2 15 4 Dioxan 4 ml NAPI 7.75 5 4 Chlorobenzene 4 ml NAPI + 2 ml TDI 6.00 20 4 Chlorobenzene 4 nil NAPI + 2 ml TDI 6.00 58 4 Chlorobenzene 4 ml ATI +2 ml TDI 6.00 58 4 Chlorobenzerte 4 ml OTI + 2 ml TDI 3.50 58 4 Dioxan 4 ml TI 3.50 58 4 Dioxan 4 m ATI 7.25 10 4 Acetonitrjle 4 ml DDI Reacts with 10.2 10 4 Acetonjtrjle 4 ml IPDI 11.6 10 4 Acetonitrile 4 ml IPrI

Acetonitrj le 11.2

TDI = Toluene Diisocyanate NAPI = Naphthylisocyanate TPI = Isopropylisocyanate ATI = Allylisothiocyanate IPDI = Isophoronedlisocyanate OTI = phenylisothiocyanate

DDI = Dimeryl Dilsocyanate

56

APPLICATIONS

The additional techniques investigated here offer considerable

benefits.

(1) As mentioned the gravimetric method could.be adopted for a

rapid, field type method for determination of N 2 H 4 or by use of

N2H 4 as an analytical reagent for determination of aldehydes; (2)

precipitates of aldehydes and hydrazines produce three colors,

white, yellow and yellow orange. Identification of an aldehyde might

be feasible based on its precipitate color; also, (3) here N 2 H 4 was

gravimetrically separated from MMEI and UDHR, N 2 H 4 could readily be

separated from amines, diamines and triamines using the same technique.

The highly colored compounds formed between hydrazines, amines

etc. and dinitro and trinitro compounds can be used as a method to

distinguish N2114 from other hydrazines, amines, diamines, triamines

and tetramines. The N 2 R 4 color was always more intense. Both amines

and hydrazines are presently detected using dimethylaminobenzaldehyde

which produces a yellow coloration. This colorimetric reaction suffers

because it can not distinguish amines from each other or amine from

hydrazines. By proper selection of conditions, colorimetric methods

for air pollution measurements of hydrazines and amines, diamines and

triarnines might be feasible. Also, identification of primary from

secondary and tertiary amines and secondary from tertiary amines might be

be feasible. Glass tubes containing a substrate impregnated with

57

selective dinitro,. trinitro or chloro, fluoro containing dinitro

compounds could be prepared. Known volumes of air containing amines

could be drawn through the glass tubes. The color produced would be

indicative of the amino group as well as the concentration of the

amine.

3. The reaction rate difference between N 2 H 4 and isocyanates,

isothiocyanates (aromatic and aliphatic) and diisocyanates could form

the basis for many varied techniques for the analysis of their mixtures.

Changing solvents and titrants, and adding catalyst to increase

reaction rate, offer ways in which analytical problems involving

isocyanates, diisocyanates and isothiocyanate can be solved.

58

SECTION 7

CLOSURE

In this Thesis, the versatility of using N 2 H 4 as an' analytical

reagent has been demonstrated. Hydrazine is simple to use and is

of high purity. It has been used both as a reducing agent and as a

basic agent. It is hygroscopic and highly reactive with strong

oxidizers but, when properly handled, is a powerful analytical

reagent.

Complete references for the analysis of hydrazine compounds by

oxidation methods and acid-base methods are presented.

Mixtures of N2H4 /MMH and N2H 4 /UDMH have been analyzed by a

titrimetric method in which two aliquots are titrated with potassium

iodate: (a) directly to determine the sum of the hydrazines present

and (b) to determine the NMIi or UDNH after selective reaction of the

hydrazine with salicylaldehyde. For ternary mixtures, three aliquots

are required: the sum of the hydrazines is determined with potassium

iodate; the sum of MMH and UDMH is found after selective reaction of

the hydrazine present with salicylaldehyde; and the UDM1-I content is

obtained by non-aqueous solvent titrimetry after reaction of both

hydrazine and MMII with acetic anhydride in dioxane.

Mixtures of N2R4 /UDMH and NNI-l/UDMIi have been determined by the

reaction of hydrazines with naphthyl or phenylisocyanate in non-

aqueous medium. In anhydrous acetic acid, N 2 H 4

and MMH reacted

rapidly with isocyanates but UDNR did not react appreciably in less

than 2 h at room temperature. From a total base titration using

perchioric acid the sum of the hydrazines is determined. The UDMH

content is determined by perchioric acid titration after the N 2 H 4 or

MMII have reacted with the isocyanate.

Various aldehydes, anhydrides, isocyanates and isothiocyanates

have been determined using hydrazine as an analytical reagent.

Compounds from the above functional groups were allowed to react at

room temperature for 30 min with excess hydrazine reagent. The

excess hydrazine was back-titrated with perchioric acid in dioxan.

This simple single method can be substituted for 3-4 different

methods presently used.

Mixtures of phenylisocyanate with phenylisothiocyanate have been

determined using hydrazine as an analytical reagent. Both isocyanates

and isothiocyanates react with N2114 to form semicarbazides and semi-

thiocarbazides in an alcohol medium using alcoholic HC1 as a titrant.

Only isocyanates react with N 2 H 4 in an acetic acid medium using

perchioric acid in dioxane as a titrant. Two aliquots are titrated:

(a) to determine the total isocyanate--isothiocyanate content using

alcoholic HC1 to back-titrate the excess N 2 H4reagent; and (b) to

determine the isocyanate content using perchloric acid in dioxan to

back-titrate the excess N21i4 reagent. From the difference in the two

titrations, the isothiocyanate content can be determined.

Ideas for new methods have been presented: (a) Because N 2 H 4 forms

a precipitate with certain aldehydes, rapid analytical methods for

either N 2 R 4 or these aldehydes could be developed. The height of the

precipitate in a centrifuge tube is a measure of the concentration

provided the proper test conditions are established. (b) Experiments

conducted by reacting hydrazines, amines (primary, secondary,

tertiary), diamines, triamines and detramines with dinitro, trinitro,

chiorodinitro and fluorodinitro compounds to select those dinitro

compounds which would allow development of methods for determing

hydrazines in the presence of each other and hydrazines in the presence

of amines. Highly colored compounds are produced by reacting the

hydrazine and amines with dinitro compounds; different hydrazines and

amines produce different colors. Preparation of glass tubes containing

glass beads impregnated or coated with selected dinitro compounds

could allow differentiation of one amine group from another or

hydrazine groups from amine groups. Establishment of proper test

conditions for this differentiation is required. (c) Preliminary

experiments were conducted with N 2 R 4 and aromatic and aliphatic

isocyanates, diisocyanates and isothiocyanates. Hydrazine reacts

rapidly with aromatic diisocyanates, isocyanates and isothiocyanates;

diisocyanates > either isocyanates or isothiocyanates. Based on

reaction rates of the different functional groups and the location of

the isocyanate group on the hydrocarbon chain, analytical methods

could be developed for their mixtures. Hydrazine because of its two

amine groups reacts faster than amines and could show a significant

improvement over amines as an analytical reagent for isocyanate

analysis. -

61

R1TC1c

I. I. N. Kolthoff, J. Axner.Chem. Soc. 46, 2009 (1924). A. Kurtenacher and J. Wagner, Z. anorg. Chem. 120, 261 (1921). L. Szebelledy and W. Madis, Mikrochim. Acta 57 (1937). B. R. Sant and A. K. Nukherji, Anal. Chim. Acta 20, 476 (1959). S. S. Yatnamura and D. H. Sikes, Anal. Chem. 35, 1958 (1963). N. Z. Barakat and M. Shaker, Analyst 88, 59 (1963). V. A. Benrath and K. Ruland, Z. anorg. Chem. 114, 267 (1920). S. Singh and J. R. Siefker, Anal. Chirn. Acta 36, 449 (1966). B. Singh and S. Singh, Ibid. 14, 109 (1956). A. S. Komarowsky, W. F. Filonowa, and I. N. Korenrnan, Z. anal. Chem. 96, 21 (1933). R. G. Stolle, J. prakt. them. 66, 332 (1902). E. Rupp, Ibid. 67, 140 (1903). B. Singh and A. Rehman, J. Ind. Chem. Soc. 17, 169 (1940). B. Singh and K. C. Sood, Anal. Chim. Acta 13, 301 (1955). J. D. Clark and J. R. Smith, Anal. Chem. 33, 1186 (1961).

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Mj

I. H. Issaand R. M. Issa, Anal. Chim. Acta 14, 578 (1956). B. Suseela, Ber. 88, 23 (1955). A. Berka and A. I. Busev, Anal. Chim. Acta 27, 493 (1962). K. A. Hoffman and F. Kuspert, Ber. 31, 64 (1898). B. Singh and R. Singh, Anal. Chim. Acta 10, 408 (1954). P. Jannasch and A. Jahn, Ber. 38, 1576 (1905). A. F. Weed, J. E. Zarembo, and L. H. Diamond, Food Machinery and Chemical Corp. C. A. 106 (1960). H. E. Malone, Anal. Chem. 33, 575 (1961). E. Burns and E. Lawler, Anal, them. 35, 802 (1963). N. Serencha, J. C. Hanna, and E. J. Kuchar, Anal. Chem. 37, 1116 (1965). H. E. Malone and R. A. Biggers, Ibid. 36, 1037 (1964). H. E. Malone, WADC TR 59-172 WPAFB, Ohio (1959). R. D. Dwiggins and B. F. Larrick, R & D. Symposium Report FRO 205/3 (1953) H. E. Malone and R. Barron, Anal, them. 37, 548 (1965). H. E. Malone and R. Barron, SSD-TRD-62-41, Edwards AFB, Calif. (1962). J. R. Conant and N. F. Hall, J. Am. Chem. Soc. 49, 3062 (1927). J. S. Fritz and R. T. Keen, Anal. Chem. 22, 565 (1952). J. A. Riddick, Anal. Chem. 28, 679 (1956). C. W. Wagner, R. H. Brown and R. H. Peters, J. M. Chem. Soc. 69, 2609 (1947). F. E. Critchfield and J. B. Johnson, Anal. Chem. 29, 957 (1957). S. Siggia and C. R. Stahl, Anal. Chem. 27, 1975 (1955). E. Riegler, Z. anal. Chem. 41, 413 (1902). M. Schlotter, Z. anorg. Chem. 164 (1903). E. Riegler, Z. anal. Chem. 46, 315 (1907). E. Ebler, Z. anorg. Chem. 47, 377 (1905). D. D. Van Slyke, A. Hiller, and K. C. Berthelsen, J. Biol. Chem. 74, 659 (1927). W. Strecker and L. Shartow, Z. anal. Chem. 64, 218 (1924). K. S. Panwar, N. K. Mathur, and S. P. Rao, Anal. Chim. Acta 24, 541 (1961). K. S. Panwar, S. P. Rao, and J. N. Gaur, Ibid. 25, 218 (1961). W. L. Shilling and B. T. Hunter, Anal. Chem. 37, 1421 (1965). J. E. Ruch and J. B. Johnson, Anal. Chem. 28, 69 (1956). F. P. Clift and R. P. Cook, Biochem. J. 26, 1800 (1932). R. E. Houghton, Amer. J. Pharm. 106, 62 (1934). H. A. Iddles and C. E. Jackson, Ind. Eng. Chem., Anal. Ed. 6, 454 (1934). W. Schoniger, H. Lieb, and K. Gassner, Mikrochim. Acta 38, 165 (1951). K. J. Monty, Anal. Chem. 30, 1350 (1958). E. F. L. J. Anet, J. Chromatog. 9, 291 (1962). A. Jart and J. Bigler, Ibid. 23, 261 (1966). S. Siggia and J. G. Hanna, Anal. Chest. 23, 1717 (1951). L. G. Radcliffe and S. Medofski, J. Soc. Chem. Ind. (London) 36, 628 (1917). D. N. Smith and W. M. D. Bryant, J. Am. Chest. Soc. 58, 2452 (1936). J. B. Johnson and C. L. Funk, Anal. Chest. 27,1464 (1955). S. Siggia and Floramo, Anal. Chem. 25, 797 (1953). S. Siggia and J. C. Hanna, Anal. Chem. 20, 1084 (1948). P. M. Beazley, Anal. Chest. 43, 148 (1971).. H. E. Stagg, Analyst London 71, 557 (1946). W. Siefken, Ann. 562, 99 (1949).

63

A. G. Williamson, Analyst London 77, 372 (1952). E. A. Navyazhskaya, Khim. Prom. 432 (Chem. abstr. 51), 8585 (1956). K. A. Kubitz, Anal. Chem. 29, 814 (1957). G. A. Strongin, A. N. Bodrovaand V. I. Smirnov, Anal. abstr. 9, 4755 (1961). 0. Mikl, Kozarstvi 15, 224; (Chem. abstr. 65, 12350) (1965). A. M. Ryadkina and A. S. Kalika, Chem. abstr. 67, 17654 (1966). A. P. Grehov, V. V. Shevchevko and K. A. Kornev, Zh, Anal. Khim 21, 1398 (1966). S. S. Lord, Anal. Chem. 29, 497 (1957). A. I. Finkelshtein and E. N. Boitsov, Zavod. Lab. 26, 959 (1960). B. A. Burns, Anal. Chem. 35, 1279 (1963). G. G. Greth, R. C. Smith and G. 0. Rudkin, Jr., J. Cell. Plast. 1, 159 (1965). F. A. Zhokhova and V. V. Zharkov, Plast. Massy 63; (Chem. abstr. 67, 82587) (1967). C. S. Kitukhina and V. V. Zharkov, ibid. 60 (Chem. abstr. 69, 36620) (1968). N. R. Nebauer, G. Skaeckoski, R. C. White and A. Kany, Anal. Chem. 35, 1647 (1963). Yu. A. Strepikheev, R. A. Semenova and A. N. Ushakov, Zh, Anal. Khim. 20, 757 (1965). W. W. Hanneman and L. L. Robinson, J. Gas Chromatogr. 6, 256 (1968). S. V. Nikeryasova and G. D. Litovchenko, Zh. Anal. Khim. 23, 309 (1968). G. W. Ruth, J. Gas Chromatogr. 6, 513 (1968). A. Kjaer and K. Rubinstein, Acta. Chem. Scand. 7, 528 (1953). Z. Nagashima and M. Makagawa, (Chem. abstr. 54, 774) (1957). L. A. Appelqvist and E. Josefsson, Acta. Chem. Scand. 19, 1242 (1965). P. Langer and K. Gschwendtova, J. Sci. Food Agr. 20, 535 (1969). E. Dieterich, Pharm. Z. No. 79.2. Anal. Chem. 45, 262 (1900). H. Roth, Mikrochim. Acta. 766 (1958). B. S. Karten and T. S. Na, Nicrochem. J. 3, 507 (1959). J. A. Vinson, Anal. Chem. 41, 1661 (1969). R. M. Jones, Anal. Chem. 38, 338 (1966). L. A. Dee and A. K. Webb, Anal. Chem. 39, 1165 (1967).

64

Analylica Chimica Acts 87 Elsevier Publishing Company, Amsterdam Printed in The Netherlands

THE DETERMINATION OF MIXTURES OF HYDRAZINE, MONOMETHYL-HYDRAZINE AND i,i-DIMETHYLHYDRAZINE

H. E. MALONE* AND D. Al. W. ANDERSON

Chemistry Department, The University, Edinburgh EH9 3ff (Scotland)

(Received July 29th, 2969)

Mixtures containing hydrazine and monomethyihydrazine (MMH) can be analysed by a differential oxidation method'. Non-aqueous methods for analysing admixtures of hydrazine with i,i-dimethylhyd.razine 2 (UDMH) or with secondary amines 34 have also been described; the UDMH or secondary amines were titrated with perchioric acid after the hydrazine had been removed by reaction with salicyl-aldehyde 2. If the salicylaldehyde is replaced by either acetic anhydride 5 or phenyliso-cyanate 6, both hydrazine and MMH can be removed from activity in the solution, and therefore the analysis of other combinations of hydrazines becomes possible. SERENCHA et al. 7 extended MALONE'S method 2 by using salicylaldehyde in the presence of excess of perchioric acid to determine admixtures of hydrazine and MMH. Such mixtures can also be analysed by gas chromatography 8 ' 9 .

Nevertheless, simple rapid chemical methods are still useful, e.g. in the analysis of mixtures of hydrazines blended for use as rocket fuels. This paper describes simple procedures for analysing admixtures of hydrazine with MMH and of hydrazine with UDMH. The total hydrazine content is found by titration with iodate'°; addition of salicylaldehyde converts the hydrazine to salicylaldazine (disalicyihydrazine) which is removed by filtration, and subsequent titration with standard potassium iodate gives the MMH or UDMH content. This procedure can be combined with the non-aqueous titration method described previously 5 to give a method for the analysis of mixtures of hydrazine, MMH and UDMH; effective removal of the hydrazine and MMH as the corresponding hydrazides by adding acetic anhydride allows the UDMH present to be determined in dioxane as solvent with perchloric acid in acetic acid as titrant.

EXPERIMENTAL

Analyses of mixtures of hydrazine and monomethyihydrazine (Method A) Preparation of samples. By pipette, add 1.5 ml of the mixture of hydrazines to

a tared 50-ml standard flask containing 20 ml of distilled water and io ml of acetic acid. Cool to room temperature and weigh to o.i mg, by difference. Dilute to the mark with distilled water and mix carefully.

Determination of hydrazi'ne +monomethylhydrazine. By pipette, add an aliquot (5 ml) of the hydrazine mixture to a 500-ml iodine flask containing 50 ml of 6 N hy-drochloric acid. Add 25 ml of 12 N hydrochloric acid and 20 ml of chloroform. Titrate * Permanent address: Air Force Rocket Propulsion Laboratory, Edwards, Calif.

Anal. Chim. Acta, 48 (1969) 87-91

88 H. E. MALONE, D. M. W. ANDERSON

rapidly with o.i M potassium iodate'°, with shaking, until the dark brown colour becomes pale. Then add the iodate dropwise until the purple colour of the chloroform layer becomes colourless and the aqueous solution is yellow. This gives titre "A1".

Determination of monomethylhydrazine. By pipette, add an aliquot (5 ml) of the mixture of hydrazines to a 400-ml beaker containing 50 ml of 6 N hydrochloric acid. Add io ml of a solution of salicylaldehyde in acetic acid (io%, v/v). The hydra-zine gives a yellow precipitate of salicylaldazine. After 15 nun, filter through Whatman No. 540 paper on a Buchner funnel, wash the precipitate several times with distilled water, and then transfer the filtrate to a 500-ml iodine flask, rinsing with several small portions of distilled water. Add 25 ml of 12 N hydrochloric acid and 20 ml of chloroform. Titrate rapidly with o.i M potassium iodate as described above for hy-drazine +monomethylhydrazine. This gives titre "A2". For calculation, see below.

Analyses of mixtures of hydrazine and I,I-diinethylhydrazine (Method B) Preparation of sample. Use the procedure outlined in Method A above. Determination of hydrazine + i,r-dimethylhydrazine. Use the procedure detailed

in Method A for hydrazine +monomethylhydrazine, but ensure that the temperature lies within the range _100 to + io° by cooling in a carbon dioxide—acetone mixture. The titration can also be carried out potentiometrically with a platinum—calomel electrode system. This gives titre "B1".

Determination of i,I-dimethylhydrazine. Use the procedure detailed in Method A above for monomethyihydrazine, but maintain the temperature within the range

I00 to + 100. The potentiometric end-point lies between 0.67 and 0.70 V. To mini-mise side-reactions, complete the titration" within 3-5 mm. This gives titre "B 2".

Calculations N2H4 + K103 + 2HC1 = KO + ICI + N2 + 3H20 CH3 .NH.NH2 + K103 + 2HC1 = KC1 + Id + CH3OH + N2 + 2H20 2[(CH3 ) 2N.NH2] +K103 +2HC1 = (CH3)2N.N = N.N(CH 3)2 + KC1 +ICJ +3H20 Let the K103 molarity = M. Then:

% hydrazine = 320M [(A1 —A 2) or (B 1 —B2)]

sample wt. (g) X 10

% MMH = 4.60MA2

sample wt. (g) X 10

%UDMH = I202M B2 sample wt. (g) x ro

Analyses of mixtures of hydrazine, monomethylhydrazine, and i,r-dimethylhydrazine (Method C)

Preparation of sample. By pipette, place o.8 ml of the mixture of hydrazines into a tared 50-ml standard flask containing 20 ml of acetic acid. Weigh to o.i mg, by difference. Dilute to the mark with distilled water, and mix carefully.

Determination of hydrazine +nzonomethylhydrazine +I,r-dimethylhydrazine. By pipette, add an aliquot (io ml) of the hydrazine mixture to a 500-ml iodine flask con-taining 50 ml of 6 N hydrochloric acid. Proceed exactly as described in Method A above for the determination of hydrazine +monomethylhydrazine with potassium iodate. This gives titre "C,".

Anal. C/jim. Ada, 48 (1969) 87-91

THE ANALYSIS OF HYDRAZINE MIXTURES 89

Determination of mon.oinethylhydrazine + i,i-dimethylhydrazine. By pipette, add an aliquot (io ml) of the mixture of hydrazines to a 400-ml beaker containing 50 ml of 6 N hydrochloric acid. Add io ml of a solution of salicylaldehyde in acetic acid (io%, v/v) and complete the determination of MMH + UDMH as described in Method A above for the determination of MMH alone. This gives titre "C2".

Determination of i,i-dim ethylhydrazi'ne. By pipette, add an aliquot (2 ml) of the mixture of hydrazines to a ioo-ml beaker containing 20 ml of dioxane. Add 2 ml of acetic anhydride; both the hydrazine and monomethyihydrazine react to give hydra-zides. Leave the reaction mixture for 30 mm, and then titrate with 0.1 N perchioric acid in acetic acid; conduct a blank determination using the reagents only. The difference gives titre "C3".

Calculations. Let the K10 3 molarity=M, and the HC104 normality =N. Then:

% hydrazine - M(Ci -C2 ) =x 3.201 - sample wt. (g) x 5

% UDMH - NC 3 6.oi - sample wt. (g) X 25

MCI -(x+.'ul % MMH = Ioo_4•6o 11 [sampiewt (g)

X5 2/i

RESULTS

Experiments with a large number of aldehydes showed that salicylaldehyde was the most suitable for the selective precipitation of hydrazine; it was also established

TABLE I

ANALYSES OF HYDRAZINE-MONOMETHYLHYDRAZINE MIXTURES

Found (%) Theoretical (%) Difference (%)

N2H4 MMH N2H4 MMH N2H4 MMH

82.5 15.9 82.5 15.9 0.0 0.0

57.1 41.2 57.6 41.3 -0.5 -0.1

51.9 46.9 52.2 46.8 -0.3 +0.1

30.7 68.3 30.5 68.9 +0.2 -o.6 23.2 76.6 22.8 77.3 +04 -0.7 17.6 81.4 18.o 81.7 -0.4 -0.3

TABLE II

ANALYSES OF HYDRAZINE-DIMETHYLHYDRAZINE MIXTURES

Found (%) Theoretical (%) Difference (%) N2H4 UDMH N2H4 UDMH N2H4 UDMH

71.0 27.8 71.2 27.6 -0.2 +0.2 50.9 47.7 50.5 48.1. +0.4 -0.4 45.2 54.4 45.3 54.1 -0.1 +0.3 31.3 66.6 31.8 67.1 -0.5 -0.5

Anal. Chim. Ada, 48 (1969) 87-91

90 H. E. MALONE, D. M. W. ANDERSON

that only i ml of salicylaldehyde was required for the conditions described in Methods A and B.

Series of test mixtures of (a) hydrazine with MMH and (b) hydrazine with UDMH were prepared and analysed by Methods A and B. The results obtained are shown in Tables I and II respectively.

Table III shows the results obtained for all three components in test mixtures by Method C.

TABLE III

ANALYSES OF HYDRAZINE-MMH-UDMH MIXTURES

Found (%)

Theoretical (%)

Difference (%)

N2H4 MMH UDMI-]

N2H4 MMH UDMH

N2H4 MMH UDMH

35.9 32.5 29.8 36.9 31.9 29.1 -1.0 +0.6 +07 36.8 30.8 28.9 37.6 30.9 29.3 —o.8 —o.i -0.4

DISCUSSION

Alternative analytical procedures for the reactions described here are possible. For example, in the determinations depending on the selective precipitation of one or more components, the precipitate could be filtered directly into the vessel used for the determination of MMH. The % hydrazine could also be determined gravimetrically as the azine; since this is soluble in chloroform, the titration could alternatively be conducted directly, without a filtration stage, by adding excess (5o ml) of chloroform. Unfortunately, the azine gives a yellow chloroform layer; the authors prefer to re-move the azine precipitate by filtration. After this is done, the determination of MMH and UDMH (in the ternary mixture case) can be conducted potentiometrically, provided that the platinum—calomel electrode system is not coated by the azine nor by excess salicylaldehyde; rapid titration (I,. 10 mm) within the temperature range _50 to

+5° is necessary to prevent side-reactions from occurring between potassium iodate and UDMH".

The well-known disadvantages of methods in which one component is found by difference apply here to the determination of the monomethylhydrazine present. Ammonia and aniline are common impurities in commercial hydrazine; nitrosodi-methylamine, dimethylamine and other compounds are found 5 in MMH and UDMH.

We thank the Olin Corporation, New Haven, Conn., and the F.M.C. Corpora-tion, Princeton, N.J. for providing quantities of hydrazine, monomethylhydrazine, and i ,i-dimethylhydrazine. We acknowledge the award of an American Air Force Systems Command Study Fellowship (to H.E.M.) which allowed these studies to be carried out in the University of Edinburgh.

SUMMARY

Admixtures of hydrazine and monomethylhydrazine (MMH) and of hydrazine with i,i-dimethylhydrazine (UDMH) can be analysed by a titrimetric method in which

Anal. Chim. Ada, 48 (1969) 87-91

THE ANALYSIS OF HYDRAZINE MIXTURES 91

two aliquots are titrated with potassium iodate: (a) directly to determine the sum of the hydrazines present, and (b) to determine the MMH or UDMH after selective reac-tion of the hydrazine with salicylaldehyde. For ternary mixtures, three aliquots are required: the sum of the hydrazines is determined with potassium iodate; the sum of MMH and UDMH is found after selective reaction of the hydrazine present with sali-cylaldehyde; and the UDMH content is obtained by non-aqueous solvent titrimetry after reaction of both hydrazine and MMH with acetic anhydride in dioxane.

RESUME

Des mélanges d'hydiazine et de monométhylhydrazine (MMH), d'hydrazine et de i,i-diméthylhydrazine (UDMH) peuvent être analyses par dosage titrimétrique. Cette méthode consiste a titrer deux parties aliquotes a l'aide d'iodate de potassium: (a) directement pour determiner le total des hydrazines présentes et (b) pour deter-miner MMH ou DDMH après reaction selective de l'hydrazine avec la salicylaldéhyde. Pour des mélanges ternaires trois parties aliquotes sont nécessaires: le total des hydrazines est déterminé par iodate de potassium; la somme MMH +UDMH est obtenue après reaction selective de l'hydrazine avec salicylaldéhyde; enf in la teneur en UDMH est mesurée par titrage en milieu non aqueux après reaction de l'hydrazine et de MMH avec anhydride acétique dans le dioxane.

ZUSAMMENFASSUNG

Mischungen von Hydrazin und Monomethyihydrazin (MMH) und von Hydra-zin mit i,i-Dimethylhydrazin(UDMH) konnen massanalytisch bestimmt werden. Dabei werden zwei aliquote Teile mit Kaliumjodat titriert und zwar wird zunächst die Summe der vorhandenen Hydrazine bestimmt und dann das MMH oder UDMH nach selektiver Reaktion des Hydrazins mit Salizylaldehyd. Bei ternären Mischungen wird zunächst die Summer der Hydrazine mit Kaliumjodat bestimmt, dann MMH und UDMH nach Reaktion des Hydrazins mit Salizyaldehyd und schliesslich der 1.JDMH-Gehalt durch Titration in nichtwassrigem Losungsmittel nach Reakt ion sowohl von Hydrazin als auch MMH mit Essigsaureanhydrid in Dioxan.

REFERENCES

i J. D. CLARK AND J. R. SMITH, Anal. Chem., 33 (1961) 1186. 2 H. E. MALONE, Anal. Chem,, 33 (1961) 575.

H. E. MALONE AND R. BARRON, Anal. Chem., 37 (1965) 548. H. E. MALONE AND R. BARRON, SSO-TRD 62-41, AFRPL, Edwards, Calif. H. H. MALONE AND R. BIGGERS, Anal. Chem., 36 (1964) 1037.

6 H. E. MALONE AND D. M. W. ANDERSON, Anal. Chim. Acta, 47 (1969) 363. N. SEREECHA, J. G. HANNA AND E. KIJCHAR, Anal. Chem., 37 (1965) 1116.

8 R. M. JONES, Anal. Chem., 38 (1966) 338.

9 L. A. DEE AND A. K. WEBB, Anal. Chem. , 39 (1967) 1165. io G. S. JAMIESON, Am. J. Sci., 33 (1912) 352. ii W. R. MCBRIDE AND H. W. KRUSE, Navord Project 5263 (NOTS 1475-1956).

Anal. Chins. Acta, 48 (1969) 87-91

Anal ylica Chimica Ada 363 Elsevier Publishing Company, Amsterdam Printed in The Netherlands

An acid-base-isocyanate method for the analysis of admixtures of hydrazi ne with 1,1 -di methyl hyd razine, and monomethyl hyd razine with 1,1-dimethylhydrazine

Hydrazine and its derivatives are now used extensively as rocket fuels, in fuel cells, and in a wide variety of industrial processes. A gas-evolution method for the determination of milligram amounts of hydrazines has recently been described', together with a brief review of the other methods of analysis available.

Mixtures of hydrazine with its methyl derivatives are, however, now commonly used; chemical and instrumental methods of analysis for such mixtures have been described27, including a differential reaction-rate acetylation method 8 and, most recently, a proton magnetic resonance method 9 . Rapid, chemical methods offer many advantages, however, e.g. for field investigations, and this communication describes a useful differential reaction-rate method in which either phenylisocyanate or naphthylisocyanate can be used.

In alcoholic solution, with ethanolic hydrochloric acid as titrant, hydrazine (N2H4), monomethylhydrazine (MMH), and I,i-dimethylhydrazine (UDMH) all react with isocyanates at about the same rate to form semicarbazides. In anhydrous acetic acid, however, N21 14 and MMH react rapidly (MMH slightly slower than N2H 4) with isocyanates, but UDMH does not react appreciably in less than 2 h at room temperature.

Reactions The experimental procedure is based on the reaction of N2114, MMH, and

UDMH with either phenylisocyanate or naphthylisocyana,te (R.NCO) to give the

Anal. Chisn. Ada, 47 (1969) 363-366

364 SHORT COMMUNICATIONS

semicarbazjdes NHI .NH.CO.NH.R, CHrNHNHCONH•R, and (CH3)2•N•NH.00.- NH•R respectively. In acetic acid, the rate of formation of the latter is very slow.

Preparation of sample By pipette, add the mixture of hydrazines (0.4 ml) to a tared volumetric flask

(50 ml) containing about 30 ml of anhydrous acetic acid; obtain the sample weight by difference. Make up to the mark with the acetic acid and mix carefully.

Determination of total hydrazines Add an aliquot (5.00 ml) of the mixture of hydrazines to a 50-ml beaker

containing 20 ml of a mixture of acetic acid and dioxan (i : i). Add 4 drops of quinaldine red indicator, 0.2% in acetonitrile. Titrate to a colourless end-point with o.I N perchloric acid in dioxan to obtain titre "A". Titrate a blank for the reagents and indicator to obtain titre "a".

Determination of i,I-dimethylhydrcizine Add an aliquot (5.00 ml) of the mixture of hydrazines to a 50-ml beaker

containing 20 ml of the acetic acid—dioxan mixture and i ml of either naphthyliso-cyanate or phenylisocyanate. (Use 2 ml for MMH/UDMH mixtures.) Set aside for 30 mm (a white precipitate forms). Add 4 drops of the quinaldine red indicator, and titrate to a colourless end-point to obtain titre "B". By titrating a blank similarly, obtain titre "b".

Calculations

%N2114 (or MMH) = (A—a)—(B—b)NHC1O4•3.2o (or 4.60)

to (sample weight)

%UDMH = (B - b) N HCI04 6.oi

io (sample weight)

Results and discussion The effect of time and of the isocyanate concentration on the reactions is

TABLE I

EFFECT OF TIME ON THE REACTION OF VARIOUS HYORAZINES WITH pHENYLIs0cYANATE (1.0 nil) AT 19 °

Time (min) ml HC104 (o.i N) used

For N2H4 For MMH For UDMH

7.90° 5.00° 7.10°

5 0.26 1.90 7.10 15 0.19 1.19 7.08 30 0.15 1.05 7.09

45 o.16 0.77 7.10 6o 0.18 0.70 7.08

75 0.17 0.30 7.05

a Without phenylisoCyanate.

Anal. Chim. Ac/a, 47 (1969) 363-366

SHORT COMMUNICATIONS 365

shown in Tables I and II. At least 0.4 ml of phenylisocyanate and a reaction time Of 15 min must be used for the effective 0.04 ml of hydrazine used here. For MMH, however, 2 nil of the isocyanate and 30 min reaction time is required; UDMH gives no significant reaction under these conditions. After 3 h at 19° , however, white crystals of i,i-dimethylphenylsemicarbazide begin to form, but the reaction solutions are still basic after 18 h.

TABLE II

EFFECT OF VARIOUS CONCENTRATIONS OF PHENYLISOCYANATE

Plienyliso- cyanate (ml)

ml HC104 (o.i N) used

For N2H4 For MMH For UDMH

0.0 8.2o 5.06 7.05 0.2 3.00 2.05 7.05 0.4 0.17 1.25 7.05 o.6 o.18 0.75 7.05 0.8 0.14 o.8o 7.03 1.0 0.21 0.55 7.00 2.0 - 0.10 7.00 3.0 - o.o6 -

a 20-40 min allowed for the reactions at 19 °

Water affects the analysis of hydrazines with isocyanates by causing the end-point of quinaldine red (red to colourless) to revert to red. The reason for this is shown in the equations below; hydrolysis of the isocyanate gives the amine which eventually reacts with sufficient isocyanate to give a substituted urea derivative.

R•NCO+H20 - R•NH CO2 H ---> R•NH2+CO2 (i)

R•NH2+R•NCO - R•NHCO•NHR (2)

The water content of the acetic acid can be reduced satisfactorily by the molecular-sieve technique 3 . Acetic anhydride cannot be used since it reacts 9 with N2H4 and MMH; it can, however, be added as required during the titration of UDMH. Potas-sium cyanate, potassium cyanide, lead thiocyanate, phenyl and methyl isothiocya-nates give no reaction with N 2H4 , MMH, or UDMH in acetic acid media.

TABLE III

ANALYSIS OF N1H4/UDMH ADMIXTURES

Experimental (%)

N2H4 UDMH

Theoretical (%)

N1H4 UDMH

Variation (%)

N2H4 UDMH

82.4 13.9 82.6 14.0 +0.2 +0.1

74.0 23.6 73.4 23.5 -o.6 -o.i 64.7 32.6 65.1 32.2 +04 +04 60.1 37.6 59.6 37.9 -0.5 +0.3 54.1 44.0 53.6 44.3 -0.5 +0.3 48.9 49.4 48.4 49.6 -0.5 +0.2 42.5 55.8 42.2 56.0 -0.3 +0.2 32.7 66.o 32.0 66.7 -0.7 +07 20.2 78.5 19.5 79.0 -0.7 +0.5

Anal. Chim. Ada, 47 (1969) 363-366

366 SHORT COMMUNICATIONS

TABLE IV

ANALYSIS OF MMH/UDMH ADMIXTURES

Experimental (%) Theoretical (%) Variation (%)

MMH UDMH MMH UDMH MMH UDMH

76.1 23.7 76.8 23.2 +0.7 -0.5 85.6 13.6 85.8 14.2 +0.2 +0.6 11.2 88.7 ,o.8 89.2 -0.4 +0.5 25.5 74.0 25.8 74.2 +0.3 +0.2 47.0 52.4 47.5 52.4 +0.5 0.0 51.4 47.5 51.8 471 +0.4 -0.4

A series of mixtures of N 2H4/UDMH and MMH/UDMH were prepared for test analyses; the results are shown in Tables III and IV.

For industrial-grade hydrazines, greater accuracy can be obtained if the "contaminant titration values" for each of the hydrazines is known. MALONE AND

BIGGERS 9 reported contaminant titration values of 0.20, 0.12, and 0.04 ml for N2 114 ,

MMH, and UDMH respectively; these are corrections for any impurities in N 2H4 and MMH which behave similarly to another hydrazine (UDMH) and vice-versa.

We thank the Olin Corporation, New Haven, Conn., and the Food Machinery Chemical Corporation, Princeton, N.J., for providing hydrazine, monomethyl-hydrazine, and i,i-dimethylhydrazine. We acknowledge the award of an Air Force Systems Command Study Fellowship (to H. E. M.).

Department of Chemistry, H. E. MALONE*

The University, D. M. W. ANDERSON

Edinburgh EH9 3JJ (Scotland)

i C. P. LLOYD AND W. F. PIcKERING, Talanta, 16 (1969) 532. 2 H. E. MALONE, Anal. Chem., 33 (1961) 575. 3 E. BURNS AND E. LAWLER, Anal. Chem., 35 (1963) 802.

N. SERENCHA, J. G. HANNA AND E. KUCHAR, Anal. Chem., 37 (1965) 1116 . 5 H. M. JONES, Anal. Chem., 38 (1966) 338. 6 L. A. DEE AND A. K. WEBB, Anal. Chem., 39 (1967)1165. 7 A. F. WEED, J. E. ZAREMBO AND L. H. DIAMOND, Analytical Me/hod CA-io6, Food Machinery

and Chem. Corpn., May 1960. 8 J. C. MACDONALD, Anal. Chim. Ac/a, 44 (1969) 391. 9 H. E. MALONE AND R. A. BIGGERS, Anal. Chem., 36 (1964) 1037.

(Received May 20th, 1969)

* Permanent address: Air Force Rocket Propulsion Laboratory, Edwards, Calif. (U.S.A.)

Anal. Chim. Ac/a, 47 (1969) 363-366

ABSTRACT OF THESIS

Name of of Cadjdate ........ H EcPiiard .a1 one .

Address ....... 41 LancasterCa..forn.a4 ....U.SA.

Degree...................................................................................................Date ary74

Title of Thesis ... !°!... y H..y...d..r..a...z..i..n..e... ..C..o...m..p...o..u..n...d..s.. ...a..n..d... ..T.....e.. Use of Hydrazine as an Analytical Reagent

The versatility of using 1H4 as an analytical reagent haó been demonstrated. High purity NA is simple to use. Although hygroscopic and highly reactive with strong oxidizers, It can be safely used and Is a powerful tool as a reducing agent and as a basic agent.

Complete references for the analysis of bydrazino compounds by oxidation methods and acid-base methods are presented,

Viethods for determination of 2H4/U1U and 2t4/ 1}/UTh have been presented. The method used potassium iodate as a titrant to determine the total hydrazine content before and after salicylaldehyde was used to selectively precipitate hydrazine from the mixtures. For all three hydrazines, the above lodate-aldehyde method was incorporated with a non-aqueous titration method.

Ron-aqueous titration methods for determination of 2ILDI and /Ui are presented. The methods are based on the selective reaction of 2H4 and with phenylisocyanate and naphthyl$socyanato; UDH did not react appreciably in less than 2 h. at room temperature.

51; 1gn.-aqueous titration methods for determination of various a1dehyde, an Isocyanates and isothiocyanatos are presented. An excess of N H 4 is allowed to react with the functional group and the unreacted H 4 reagent is titrated with perchloric acid.

Pon-aquous titration methods for determination of phenylisocyanate and phenylisothiocyanate are presented. The method is based on the reaction of 024 with phenylisocyanato and phenylisothiocyanato in alcoholic cedium using alcoholic HC1 as a titrant; UPH4 is essentially unreactive with phenylisothlo- cyanate in dioxana medium using perchloric acid. By Incorporating two titratlons, two solvents and two titrants, methods for the mixtures were developed.

New ideas are presented for analyzing hydrazines and for using hydrazine to determine other compounds. Aldehydes are reacted with hydrazine to produce precipitates. Based on this reaction, methods for hydrazinos and aldehydes could be developed.

L Hydrazines, amines, dlainines, triamines and tetranines reacted with dinitro, trinitro and dinitro compounds containing chlorine and fluorine groups to produce highly colored compounds. Proper selection of the dinitro compounds would allow detection procedures for hydrazines and amines to be developed. Further work In this area could result in air pollution detection methods for hydrazines and amines.

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