Answer 1

Anionic detergents

Anionic detergents are of two types:

1.Sodium alkyl sulphates: These detergents are sodium salts of long chain alcohols. They are prepared by first treating these alcohols with concentrated sulphuric acid and then with sodium hydroxide. Examples of these detergents include sodium lauryl sulphate (C₁₁H₂₃CH₂OSO₃⁻Na⁺) and sodium stearyl sulphate (C₁₇H₃₅CH₂OSO₃⁻Na⁺).

2.Sodium alkylbenzenesulphonates: These detergents are sodium salts of long chain alkylbenzenesulphonic acids. They are prepared by Friedel-Crafts alkylation of benzene with long chain alkyl halides or alkenes. The obtained product is first treated with concentrated sulphuric acid and then with sodium hydroxide. Sodium 4-(1-dodecy) benzenesulphonate (SDS) is an example of anionic detergents.

Answer 2

Anionic detergents are called so because a large part of their molecules are anions. ‘These are of two types:

(a)Sodium alkyl sulphates: For example, sodium lauryl sulphate, C₁₁H₂₃CH₂OSO₃ Na⁺.

(b)Sodium alkylbenzenesulphonates.Vor example, sodium 4-(l-dodecyl) benzenesu Iphphonate (SDS).