A detergent is a surface active agent used for cleaning dirty surfaces. It contains a non polar hydrocarbon chain (hydrophobic part) and polar group (hydrophilic part) within the molecule. On the basis of charge on polar part, detergents are classified as follows:
(A) Anionic detergents in which large part of the molecule is anion and it is the anionic part of the molecule which is involved in their cleansing action.
e.g., alkylbenzenesulphonate.
(B) Cationic detergents in which major part of the molecule is cation and it is the cationic part of the molecule which is involved in their cleansing action. These are mostly acetates or chlorides of quaternary amines e.g., Cetyltrimethylammonium chloride.
(C) Non-ionic detergents are esters of high molecular mass formed by reaction between polyethylene glycol and stearic acid.
Detergents are preferred over soaps as they work even in hard water and acidic water They have powerful cleansing action.
