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Aldehydes, Ketones and Carboxylic Acids

Carbonyl Group – Nomenclature and Structure

Nomenclature

In the IUPAC system, aliphatic carboxylic acids are named as follows:

  • By replacing the ending ‘− e’ in the name of the corresponding alkane with ‘− oic acid’

  • Carboxylic carbon is numbered one.

  • If more than one carboxyl groups are present, then the ending ‘− e’ of the alkane is retained.

  • The number of carboxyl groups is indicated by adding prefix, d, tri, etc. to the term ‘oic’.

The given table lists the common and IUPAC names and structures of some carboxylic acids.

Names and Structures of Some Carboxylic Acids

Structure

Common name

IUPAC name

HCOOH

Formic acid

Methanoic acid

CH3COOH

Acetic acid

Ethanoic acid

CH3CH2COOH

Propionic acid

Propanoic acid

CH3CH2CH2COOH

Butyric acid

Butanoic acid

(CH3)2CHCOOH

Isobutyric acid

2-Methylpropanoic acid

HOOC-COOH

Oxalic acid

Ethanedioic acid

HOOC −CH2-COOH

Malonic acid

Propanedioic acid

HOOC -(CH2)2-COOH

Succinic acid

Butanedioic acid

HOOC -(CH2)3-COOH

Glutaric acid

Pentanedioic acid

HOOC -(CH2)4-COOH

Adipic acid

Hexanedioic acid

HOOC -CH2-CH(COOH)-CH2-COOH

Propane-1, 2, 3-

tricarboxylic acid

Benzoic acid

Benzenecarboxylic acid

(Benzoic acid)

Phenylacetic acid

2-Phenylethanoic acid

Phthalic acid

Benzene-1, 2-dicarboxylic

acid

Structure of Carboxyl Group

  • Carboxyl carbon is less electrophilic than carbonyl carbon because of resonance.

  • Bonds to the carboxyl carbon lie in one plane and are separated by about 120°.

Methods of Preparation of Carboxylic Acid

  • From primary alcohols

  • From primary aldehydes

Oxidising agents − HNO3, KMnO4, K2Cr2O7

Mild oxidising agents − Tollen’s reagent and Fehling’s reagent

  • From alkyl benzenes

  • 1° and 2° alkyl benzene are oxidised in this manner.

  • Tertiary group is not affected.

  • From nitriles and amides

  • From Grignard reagents

  • From acyl halides

  • From acyl anhydrides

  • From esters

  • Ester Carboxylic acid

Example:

  •  

Examples:

Nomenclature

In the IUPAC system, aliphatic carboxylic acids are named as follows:

  • By replacing the ending ‘− e’ in the name of the corresponding alkane with ‘− oic acid’

  • Carboxylic carbon is numbered one.

  • If more than one carboxyl groups are present, then the ending ‘− e’ of the alkane is retained.

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