Components for Polyamides Products of Propene

7/28/2019 Components for Polyamides Products of Propene

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Components for polyamides

Nylon was first produced on an industrial scaleby Du Pont after 1939.

Polyamides are the products of condensationbetween :

diamines and dicarboxylic acids, or betweenaminocarboxylic acids

Polyamides may also be obtained by

polymerizing lactamsThe characteristic of polyamides structure:CONH units alternating with CH2 chains


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Designation of polyamides

The use of one figure represents synthesisfrom a single bifunctional compound, e.g.Nylon 6

Two figures: synthesis from twocomponents, e.g. diamine and dicarboxylicacid

The values of the digits in the figuressignify the number of carbon atoms ineach component, e.g. Nylon 6,6


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Uses of polyamide

In synthetic fibres, e.g. clothes,carpets

In thermoplastics

Aromatic polyamides oraramides are manufactured

from terephthalic acid orisophthalic acid

Aramides are used in flame-resistant fibres, electricalinsulation material and in tire

cords. Kevlar is used in bullet-proof

vests, in the lining ofexpensive cars and shutters ofmore expensive cameras


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Dicarboxylic acids

Adipic acid, suberic acidand sebacic acid are themost widely useddicarboxylic acids in

industry Most adipic acid is

obtained from theoxidative cleavage ofcyclohexane in the liquid

phase and Mn or Co salts(acetate or naphthenate)as catalysts


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The oxidation productsare further oxidized toadipic acid, eitherwith:

nitric acid andammoniummetavanadate/coppernitrate or

Air and copper andmanganese acetate


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Uses of adipic acid

Manufacture of Nylon 6,6

Starting material for

hexamethylenediamine

Component for polyesters

Converted to esters for use in plasticizers

and lubricants Hydrogenated to 1,6-n-hexadiol for use in

polyesters, polyurethanes and HMDA


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1,12-dodecanedioic acid

The starting material,

cyclododeca-1,5,9-

triene, is synthesized

by the trimerization ofbutadiene with a

Ziegler catalyst (TiCl4

and Et2AlCl).

Ni0 and chromiumcomplexes may also

be used as catalysts


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Production of C12 dicarboxylic acid

from cyclododecatriene

1. Hydrogenation tocycloalkane usingNi catalysts

2. Mild oxidation to C12cyclicalcohols andketones

3. Oxidative cleavage

of the ring, resultingin the formation ofthe dicarboxylic acid


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Uses of C12 dicarboxylic acid

In polyamide

In polyesters

Esterified for use as lubricants


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Hexamethylenediamine

Cyclohexanone is

oxidized to caprolactone

Caprolactone is

hydrogenated to 1,6-

hexanediol

1,6-hexanediol is

aminated with ammonia

using a Raney nickel

catalyst to give 1,6-aminohexanol


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Adiponitrile

May be obtained by:

1. Dehydrative

amination of adipic

acid with ammonia(C6 + 2N)

The reaction is

catalysed by

phosphoric acid


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2. The Monsanto

EHD (electro-

hydrodimerization)

method involves thehydrogenative

dimerization of

acrylonitrile to

adiponitrile.The net reaction is:


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The steps involved in

this reductive or

cathodic dimerization

are:


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Hydrogenation of adiponitrile

Adiponitrile can be

hydrogenated using Co-

Cu or Fe catalysts to

produce

hexamethylenediamine.


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-aminoundecanoic acid

Precursor for Nylon 11

Castor oil, the source of ricinoleicacid, is used as the startingmaterial. This is one of the fewexamples of a starting material inindustrial organic chemistry that isnot derived from fossil fuels. Whatis the advantage of this?

Following transesterification ofglycerol triricinolate withmethanol, the methyl ester ispyrotically cleaved at 3000C toyield a C7 aldehyde and the methylester of undecanoic acid. Thepresence of theOH groupslightly weakens the C-C bondthat is indicated by the dotted line,and this bond is broken atelevated temperatures.


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The methyl ester is

saponified, then

converted to 11-

bromoundecanoic acid by

peroxide-catalysed HBraddition

The product is then

reacted with ammonia,

producing -aminoundecanoic acid


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Lactams

-caprolactam, which is the cyclic amide of

-aminocaproic acid, is the most important

lactam in industry

It is used in the manufacture of nylon-6


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The manufacture of-caprolactam

involves 4 steps

1. Production ofcyclohexanone.

Most cyclohexanone

is produced fromcyclohexane. Analternative routebegins with phenol,which may beconverted tocyclohexanone inone or two steps:


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2. Oxime formation

using cyclohexanone

in the presence of a

hydroxylamine salt:

The Toray process

produces oxime by

photonitrosation of

cyclohexane:


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3. Conversion of

cyclohexanone oxime

into -caprolactam by

rearrangement in

sulphuric acid or oleum.The first step forms

lactam sulphate, which

upon neutralization with

ammonia gives the freelactam:


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4. Hydroxylaminesulphate which is usedfor producing the oxime ismanufactured by the

Raschig process, inwhich ammonium nitrite isreduced with sulphurdioxide to produce thedisulphonate, which is

then hydrolysed tohydroxylamine sulphate:


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Propene conversion products

Propylene oxide

Not as reactive asethylene oxide

Attempts at producing itby direct oxidation ofpropylene have not beensuccessful

Propylene oxide ismanufactured by thechlorohydrin process

which was once the mainroute to the synthesis ofethylene oxide:


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Propylene oxide maybe obtained byindirect oxidation orpropene by radicaloxidation usinghydroperoxides orperoxycarboxylicacids. About 40% of

propylene oxide isnow produced by thismethod.


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Peracetic acid may be

produced from acetic

acid and hydrogen

peroxide withsulphuric acid as the

catalyst:


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Secondary products of propylene

oxide

Propylene oxide is used to make 1,2-propyleneglycol, dipropylene glycol and propoxylatedproducts

Propylene glycol is used as an antifreeze and asa brake fluid and in the manufacture of alkydand polyester resins

Polypropylene glycol, obtained by the reaction

between propylene oxide and propylene glycol,are used in manufacturing non-ionic surfactants,detergents and emulsiers


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Acetone

1. Acetone may be obtained by

direct oxidation of propene by

the Wacker-Hoechst process

using PdCl2 as the catalyst.

Compare this with a similarprocess which converts

ethylene to acetaldehyde


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2. Acetone may be obtained

from isopropanol via

oxidative

dehydrogenation over Ag

or Cu catalysts ordehydrogenation over

ZnO catalysts:


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A method by Shell

and Du Pont employs

liquid-phase oxidation

of isopropanol for theproduction of

hydrogen peroxide:


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Methyl isobutyl ketone from

acetone

Methyl isobutyl ketone is the largest

volume aldol condensation product from

acetone

It is used as a solvent for cellulose

acetate, alkyd and acrylic resins; as an

extractant and as the starting material to

produce hexylene glycol


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1st step: formation ondiacetone alcohol ina base-catalysedaldol reaction

2nd step: elimination of

water, catalysed bysulphuric acid orphosphoric acid. Mesityloxide is produced


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3rd step: mesityl oxide

is hydrogenated to

methyl isobutyl

ketone using Ni or Cucatalysts


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Methacrylic acid

Methacrylic acid is used as a homo- or

copolymer and as a thickener or for

finishing

The methyl ester is its the most widely

used derivative

Acetone cyanohydrin is the sole feedstock

for methacrylic acid


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1. Acetone cyanohydrin isproduced by a base-catalysed addition ofhydrocyanic acid to acetone:

2. The cyanohydrin is reactedwith sulphuric acid toproduce methacrylic acidamide sulphate, which isthen converted to methylmethacrylate and

ammonium hydrogensulphate by reaction withmethanol. The product ismethyl methacrylate


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A process designed

by Mitsubishi

hydrolyses the

cyanohydrin to anamide, which is then

reacted with methyl

formate to give the

methyl ester andformamide:


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Uses of methyl methacrylate

For making Plexiglas,a clear plastic havingconsiderablehardness, resistance

to fracturing andchemical stability

As a co-monomer inthe manufacture ofdispersions for paintsand textiles


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Acrolein

Formerly manufactured bycondensing acetaldehyde withformaldehyde in gaseousphase over sodium silicate:

Currently all acrolein isproduced by catalytic oxidationof propene over Cu2O/SiC andI2 as the promoter. Note thatthe double bond actives themethyl group, which is

oxidised. Refer to slide 54 forother examples of methylgroups activated by eithervinylic or aromatic groups


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Uses of acrolein

Hydrogenation to allyl alcohol

Reacted with ammonia in thegaseous phase to formpyridine and -picolinemixtures

As intermediate for themanufacture of acrylic acid andacrylonitrile

For conversion into methionine(an amino acid)

For manufacture of1,3-propanediol, an intermediatefor pharmaceuticalcompounds, also used in apolyester for synthetic fibres


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Acrylic acid and its esters

Ethylene oxide andhydrocyanic acid wereformerly used in theethylene cyanohydrinprocess to formhydroxypropionitrile (inthe presence of a base)

Hydroxypropionitrile isthen reacted with an

alcohol or with water andsulphuric acid to producethe ester or the free acid:


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The Reppe process is

based on the

carbonylation of

acetylene in thepresence of water or

alcohols over a nickel

tetracarbonyl catalyst,

producing the freeacid or the ester:


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Today most acrylicacid is obtained fromdirect oxidation ofpropene with air or

oxygen using amulticomponentcatalyst of mainlymetal molybdates

with telluriumcompounds ascatalysts:


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Uses of acrylic acid and its esters

Monomers for homo- and co-polymers

used for paints and adhesives, in paper

and textiles and leather processing

These polymers are superabsorbants,

having the ability to take up large amounts

of liquids


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Allyl compounds and its secondary

products

These compoundshave the H2C=CH-CH2- functional group

Hot chlorination ofpropene, in which afree radicalsubstitution takesplace at the allyl

position, is used tomanufacture allylchloride:


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Uses of allyl chloride

1. Hydrolysis to allyl

alcohol

H2C=CH-CH2-OH

2. Epoxidation to

3. Ammonolysis to

H2C=CH-CH2-NH2


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Epichlorohydrin production

1. Reaction with

hypochlorous acid

in the aqueous

phase

2. Elimination of HCl

using calcium

hydroxide

Epichlorohydrin is used to produce glycidyl ethers e.g.


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Epichlorohydrin is used to produce glycidyl ethers e.g.

bisphenol A glycidyl ether, precursors for epoxy resins. In

the first step, the epoxide ring breaks to form a chlorohydrin

ether, but it is reformed upon elimination of HCl by NaOH


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Allyl alcohols and esters

1. Allyl alcohol fromallyl chloride:

2. By isomerization ofpropylene oxide

using lithiumphosphate as thecatalyst


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Uses of allyl alcohols

Mainly in the manufacture of glycerol.Glycerol is used as a moistening agent,antifreeze, and as a slip additive.

Glycidol, an intermediate in glycerolsynthesis, is used to synthesizepharmaceutical and cosmetic compounds,and emulsifiers.

Esters of allyl alcohols, such as maleicand phthalic acid, are used in polymers

Gl l d ti f ll l


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Glycerol production from allyl

precursors

The processes of IG

Farben (1943) and

Shell (1948) use allyl

chloride or itsconversion product

epichlorohydrin. The

latter is hydrolysed to

glycerol using 10%caustic soda:


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Allyl alcohol is

hydroxylated using

hydrogen peroxide,

producing glycidol asan intermediate, using

tungsten oxide or

salts of tungstic acid

as the catalyst:

Glycerol is used to produce alkyd resin The


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Glycerol is used to produce alkyd resin. The

reaction between phthalic anyhydride and glycerol

produces a linear, fusible resin


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Acrylonitrile

Acrylic acid nitrile or

acrylonitrile was first

manufactured in 1930 in

Germany, then USA. It

was copolymerized withbutadiene to form a

synthetic rubber, buna

N

The first synthesis (IGFarben) used ethylene

oxide:


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The method of Bayer utilizedthe addition of HCN toacetylene:

Acrylonitrile is now producedmainly by the ammoxidation of

propene. The Sohio process(part of BP) is the mostimportant ammoxidationprocess today. It uses aheterogeneously-catalysedsingle step gas-phase

oxidation of propene in thepresence of ammonia, air andsteam using Bi2O3.MoO3catalysts in a fluidized bed

In ammoxidation activated methyl groups


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In ammoxidation, activated methyl groups

are converted into nitrile groups. Examples

of such groups:

Mechanism of ammoxidation: 2 H atoms are first


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Mechanism of ammoxidation: 2 H atoms are first

abstracted from chemisorbed propene and ammonia, after

which C3H4 and NH react to give acrylonitrile


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Uses of acrylonitrile

As a monomer in the synthesis of syntheticfibres, rubbers and plastics, e.g. ABS(acrylonitrile-butadiene-styrene), SAN (styrene-acrylonitrile)

Electrodimerization of acrylonitrile producesadiponitrile

Modification of starch and cellulose

Manufcture dyes and pharmaceutical

compounds Manufacture of acrylamide, which is used as amonomer to produce polymers used in paints,flocculating agents and resings.

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Components for Polyamides Products of Propene

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