Today:Today:

Unknown 1 (review)aldehyde, ketone, alcohol, phenol

Unknown #2:

carboxylic acid, ester, anhydride, amide, amine(Cl, Br, nitro)

Questions?Questions?

2,4-dinitrophenylhydrazone (2,4-DNP)

Classification Tests for Aldehydes and Ketones

also a good derivative! →Prepare two good derivatives of each unknown if possible.

Recrystallize from ethanol/water.

• Preliminary tests

• Solubility

• Classification tests

• Derivatives

• Tollens Test:

• Jones (chromic acid): check reagent! Test is also positive for …..?

• Schiff reagent: check reagent!

Always do with a known compound to compare!

Aldehydes and Ketones

To distinguish between aldehydes and ketones:

• Preliminary tests

• Solubility

• Classification tests

• Derivatives

Aldehydes and Ketones Derivatives

Imines:2,4-dinitrophenylhydrazone

oximesemicarbazone

• Preliminary tests

• Solubility

• Classification tests

• Derivatives

Alcohols and Phenols

Solubility distinction!

Solubility:

Alcohols: “neutral”;

Phenols: very weak acids, pKa around 10, except nitrophenols!

Classification tests:

• Jones (positive for 1o, 2o alcohols, aldehydes, amines…!)

• Lucas test for 3o alcohols, 2o alcohols (slow):

• Phenols only: Complexation with Fe 3+

• Preliminary tests

• Solubility

• Classification tests

• Derivatives

• Spectra

Alcohol and Phenol Derivatives

• with 3,5-dinitrobenzoyl chloride

• urethanes

Similarly: Naphthyl urethanes

• Preliminary tests

• Solubility

• Classification tests

• Derivatives

• Spectra

• the ratio of the velocity of light in air to the velocity of light in a given medium.

• sin incident angle/sin refracted angle

• a constant at a given temperature.

• an important physical property of liquids (and gases and transparent solids!)

• Air has a refractive index of 1.000292 at 273 K/760 mm Hg for the yellow sodium D-line at 589.3 nm.

Refractive IndexRefractive Index (confirming liquid unknowns)

Unknown #2:

carboxylic acid, ester, anhydride, amide, amine

(Cl, Br, nitro)

Functional groups?

Preliminary test results?

Mp., bp. Which would you expect to have relatively high/relatively low mp.s / bp.s?

Odor Which would you expect to have a bad smell/a pleasant smell (human perspective…)

Color Which would you expect to have a color?

• Preliminary tests?

• Solubility

• Classification tests

• Derivatives

• Spectra

Carboxylic Acids Anhydrides Esters Amides Amines Nitro

What type of information do you get if your unknown

1. is soluble in water?

2. is soluble in NaOH and in NaHCO3?

3. is soluble in NaOH only, not in NaHCO3?

4. is soluble in dilute HCl solution?

5. is soluble only in conc H2SO4?

6. is not soluble in any of the above solvents?

Solubility Tests

Carboxylic Acids Anhydrides Esters Amides Amines Nitro

• Preliminary tests

• Solubility?

• Classification tests

• Derivatives

• Spectra

Carboxylic AcidsGood mp.s (consider recrystallization)

Neutralization Equivalent (titration) experimental instructions on our webpage

• Solubility

• Classification tests

• Derivatives (not done)

• Spectra

Derivatives (we do not do them in the lab):

Convert carboxylic acid into acid chloride first, then into amides

RCO2H + NaOH        RCO2(–) Na(+)

aq.   +   H2O

1.

2.

+ HCl

Define carboxylic acid by: mp., neutr. equivalent, an ester and its bp.

Esters

Classification Test

Deep-red to purple

• Preliminary tests?

• Solubility

• Classification tests

• Derivatives

• Spectra

Compare with known ester!

a hydroxamic acid

Derivatives for Esters

Hydrolyze (experimental instructions on our webpage)

… to its carboxylic acid component (mp.)

…. and its alcohol component alcohol derivative

• Preliminary tests?

• Solubility

• Classification tests

• Derivatives

• Spectra

Amine Derivatives

1. Picrates

2. Benzamides: amine + benzoyl chloride

NH 2

OH

NO 2

NO 2

O 2 N

+

• Preliminary tests?

• Solubility

• Classification tests

• Derivatives

• Spectra

Voodoo Lily Amorphophallus

Amines in plant odors … :

• UV spectra

• MiniQuiz on today’s class

• Conclusion Unknown 2

• Inert Compounds:

AlkanesAromatic Hydrocarbons

Alkyl halides

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