Logo : organicmystery.com Online Organic Chemistry Tutorial

Preparation of Carboxylic Acids

«Previous Next »

Preparation of Carboxylic Acids from Alcohols and Aldehydes

Primary alcohols and aldehydes are oxidised to corresponding carboxylic acids with oxidising agents such as :

Acidified K2Cr2O7 and Jones reagents often give some amount of esters; therefore, neutral or alkaline KMnO4 is preferred for this purpose.

Preparation of carboxylic acids from alcohol : ethanoic acid from ethanol
Preparation of carboxylic acids from alcohol : Hexanoic acid from hexanol
Preparation of carboxylic acids from alcohol : benzoic acid from benzyl alcohol

From aldehydes : Besides the above reagents, aldehydes are easily oxidised to carboxylic acids with mild oxidising agents such as Tollen's reagents.

Preparation of carboxylic acids from aldehydes using tollen's reagents : ethanoic acid from ethanal

Preparation of Carboxylic Acids from Alkylbenzene

Aromatic carboxylic acids are prepared by oxidation of alkylbenzenes with alkaline permangnate. The side chain of alkylbenzene is oxidised to -COOH irrespective of the length of the chain; the side products, however, are different depending upon the alkyl group. Take a close look at the following reactions :

Preparation of carboxylic acids from alkyl benzene : Benzoic acid from toluene
Preparation of carboxylic acids from alkylbenzene : benzoic acid from ethyl benzene
Preparation of carboxylic acids from alkylbenzene : benzoic acid from propyl benzene
Preparation of carboxylic acids from alkylbenzene : phthalic acid from o-xylene

Preparation of Carboxylic Acids from Nitriles

Hydrolysis of nitriles with H+ or OH as catalysts yields carboxylic acids.

Preparation of carboxylic acids from nitriles :

Prepare ethanoic acid from methanol :

preparation of benzoic acid from benzonitrile

One of the methods to prepare aryl nitrile is given below :

preparation of aryl nitrile

Preparation of Carboxylic Acids from amides

Amides on hydrolysis yield carboxylic acids.

Preparation of carboxylic acids from amides

Preparation of Carboxylic Acids from acid halides and anhydrides

Hydrolysis of acid chlorides yields carboxylic acids. It can be done in the following ways :

Similarly, hydrolysis of acid anhydrides yields carboxylic acids.

Preparation of carboxylic acids from acid anhydride

Preparation of Carboxylic Acids from Esters

Hydrolysis of esters either with mineral acids or alkalies gives carboxylic acid. Acidic hydrolysis of esters directly gives carboxylic acids while the basic one gives carboxylates, which upon acidification yield carboxylic acids.

Preparation of carboxylic acids from esters
Preparation of carboxylic acids from esters

Preparation of Carboxylic Acids from Grignard Reagents

The reaction of grignard reagents with crushed dry ice (solid carbon dioxide) followed by acidification with mineral acids gives carboxylic acids.

Preparation of carboxylic acids from grignard reagents
Preparation of carboxylic acids from grignard reagents

Conversions

Convert benzaldehyde to α-hydroxyphenylacetic acid.

Convert benzene to phenylacetic acid.

Convert bromobenzene to benzoic acid.

«Previous Next »