Question

Hydrolytic reaction of fats by caustic soda is known as
A. Acetylation
B. Carboxylation
C. Esterification
D. Saponification

Answer 1

Hint: Saponification reaction is the hydrolysis of an ester to form an alcohol and the carboxylic acid of corresponding salt . It is used basically in the formation of soaps which are used with hard water to form lather which is used for cleaning dirty clothes in our home.

Complete Step by Step Solution:
Hydrolysis is a process of chemical breakdown of any chemical compound due to reaction with water molecules. This process is used very much on a large scale for the production of a large number of compounds and in many useful reactions. The long chain carbohydrates , lipids and fats are esters of long chain alcohols and carboxylic acids .In the soap making industries, these esters are used for the manufacturing of soaps which is of a great importance in the industrial sector as it is used very much in almost all houses.

The process of making soaps using the process of hydrolysis of esters in the presence of caustic soda is called the Saponification reaction. In this reaction the esters present in fats , on hydrolysis by caustic soda gives alcohol and the salt of carboxylic acid in acidic or essential conditions.Saponification is usually used to refer to the soap forming reaction of a metallic alkali like caustic soda ($NaOH$) with fat and grease. For an example: $H-O-C=O{{R}_{1}}+NaOH\overset{hydrolysis}{\leftrightarrows}Na-O-C=O{{R}_{1}}+{{H}_{2}}O$

The soaps formed are then used with water for cleaning. The cleansing action of soaps includes the micelle formation which is responsible for the formation of lather and removes out the dust and grease from the clothes easily. Micelle formation takes place over the Kraft temperature only . The soaps formed are a long chain of carboxylic salts which can be expressed in the form of $R-CO{{O}^{+}}N{{a}^{-}}$.

Note: All the hydrolysis reactions of fats which are of higher hydrocarbon chains form soaps. It should be confused with detergents. Both are totally different classes of compounds although in houses, they are used for cleaning of clothes only .