Summary of Carboxylic Acids

Physical Properties

Carboxylic Acids

1. Are extremely polar
responsible for all other physical properties

2. Hydrogen bond well
responsible for high water solubility
responsible for high boiling points
form hydrogen bonded dimers - gives rise to observable spectral properties

R

O

O

H

R

O

O

H

1H nmr chemical shift >10 ppm

IR stretching frequency lower

3. Have acidic protons

Acidity depends on subtituents
Electronegative subtituents increase acidity by withdrawing electrons
inductively - strongly dependent on distance from carboxyl group

Acidity of Benzoic acid derivatives depend on position of subtituent and the
ability to withdraw electrons by resonance and inductively.

Proton transfer is fastand is the firstreaction to take place with any base or
nucleophile. Gives a carboxylate salt.

1

Synthesis of Carboxylic Acids

Oxidation of
Alcohols or Aldehydes
Alkyl benzenes - give benzoic acid derivatives
Alkenes - give Diacids

Treatment of Grignards with CO2

Examples:fill in the blanks

CH2CH3

KMnO4

Br

O

OH

2.

1.

Reactions of Carboxylic Acids(Almost all begin with proton transfer)

Reduction to alcohols

Direct Conversion to other Acyl Derivatives (only two are useful)

1. To Esters
Methyl Esters
Alkylate Carboxylate salt with methyl iodide

Treat acid with Diazomethane

Other Esters
Treat with an alcohol and H2SO4(or mineral acid)

2. To Acid Chorides
Treat acid with SOCl2(thionyl chloride)

Examples, fill in the blanks:

O

OH

O

O

2