The carboxylic acid and its derivatives are important classes of compounds in organic chemistry.

• The carboxylic acids are named by first finding out the name of parent alkane while counting the carboxyl carbon too. Then, the suffix oic acid is added to it. Some examples are given below.

  

• The acid chlorides are named after the carboxylic acid from which they are derived. The –ic acid in the IUPAC name is replaced by –yl halide. Some examples are given below.

  

• In an acid anhydride, when both the acyl groups are same, the word acid in the carboxylic acid is replaced by anhydride but, if the two acyl groups are different, the names of carboxylic acids are written in alphabetical order.

  

• In esters the alkyl group and the acyl group are specified independently. The name of the alkyl group is first written followed by the name of the acyl group.  The name is suffixed by with an oate.

  

• When naming amides, the -oic in the name of the acid is replaced with –amide. In case of substitution on the nitrogen atom, they are prefixed before the name as N-.  The substituents are always written in an alphabetical order. Some examples are provided below.

  

6.3 Reactions

The reactivity of the carboxylic acid derivatives towards nucleophilic attack follows the order:

acyl chloride > anhydride > ester > amide

This order of reactivity of carboxylic acid derivatives towards nucleophilic acyl substitution can be explained on the basis of the electron donating properties of the substituent attached to the acyl group. The greater the electron donating power of this group, the slower is the rate.

6.4 Carboxylic Acid Synthesis
6.4.1 Oxidation of Alcohols

Carboxylic acids are normally prepared from primary alcohols by oxidation using oxidizing agents such as KMnO₄ and chromic acid (Scheme 1).

Scheme 1

6.4.2 Hydrolysis of Nitriles

Another method of preparation of carboxylic acids involves the hydrolysis of nitriles by an acid or a base (Scheme 2).

Scheme 2

6.4.2 Grignard Reaction

The action of dry ice on Grignard reagent leads to the formation of carboxylic acids (Scheme 3).

Scheme 3

6.5 Acid Chloride Synthesis

The acyl chlorides may be generated from carboxylic acids by heating them with phosphorus trichloride or phosphorus pentachloride.