(i) 40% aqueous solution of formaldehyde is called formalin. It is used for preserving

biological specimens. (ii) Formalin has hardening effect, hence it is used for tanning. (iii) Formalin is used in the production of thermo setting plastic known as bakelite, which

is obtained by heating phenol with formalin. Acetaldehye (i) Acetaldehyde is used for silvering of mirrors (ii) Paraldehyde is used in medicine as a hypnotic. (iii) Acetaldehyde is used in the commercial preparation of number of organic compounds

like acetic acid, ethyl acetate etc., Acetone (i) Acetone is used as a solvent, in the manufacture of smokeless gun powder (cordite) (ii) It is used as a nail polish remover. (iii) It is used in the preparation of sulphonal, a hypnotic. (iv) It is used in the manufacture of thermosoftening plastic Perspex. Benzaldehyde is used (i) as a flavoring agent (ii) in perfumes (iii) in dye intermediates (iv) as starting material for the synthesis of several other organic compounds like

cinnamaldehyde, cinnamic acid, benzoyl chloride etc. Aromatic Ketones (i) Acetophenone has been used in perfumery and as a hypnotic under the name hypnone. (ii) Benzophenone is used in perfumery and in the preparation of benzhydrol eye drop.

XII U12-Carbonyl Compounds.indd 167 2/19/2020 5:15:11 PM

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CARBOXYLIC ACIDS Introduction

Carbon compounds containing a carboxyl function group, -COOH are called carboxylic acids. The Carboxyl group is the combination of carbonyl group

O

C and the hydroxyl group (-OH).

However, carboxyl group has its own characteristic reaction. Carboxylic acids may be aliphatic (R – COOH) or aromatic (Ar – COOH) depending on the alkyl or aryl group attached to carboxylic carbon. Some higher members of aliphatic carboxylic acids (C12 to C18) known as fatty acids occur in natural fats as esters of glycerol.