(i) Cationic detergents : Cationic detergents are quarternary ammonium salts of amines with acetates, chlorides or bromides as anions. Cationic part possess a long hydrocarbon chain and a positive charge on nitrogen atom. Hence, these are calledcationic detergents. Cetyltrimethylammonium bromide is a popular cationic detergent and is used in hair conditioners.
[CH3(CH2)15−

CH3 |

N

| CH3

−CH3]+Br− (Cetyltrimethyl ammonium bromide)
Cationic detergents have germicidalproperties and are expensive, therefore these are of limited use.
(ii) Anionic detergents : Anionic detergents are sodium salts of sulphonated long chain alcohols or hydrocarbons. Alkyl hydrogensulphates formed by treating long chain alcohols with concentrated sulphuric acid are neutralised with alkali to formanionic detergents. Similarly alkyl benzene sulphonates are obtained by neutralising alkyl benzene sulphonic acids with alkali.
In anionic detergents, the anionic part of the molecule is involved in the cleansing action. Sodium salts of alkylbenzenesulphonates are an important class of anionic detergents.
They are mostly used for household work. Anionic detergents are also usedin toothpastes.
(iii)Non-ionic detergents : Non-ionic detergents do not contain any ion in their constitution. One such detergent is formed when stearic acid reacts with polyethyleneglycol. Liquid dishwashing detergents are non-ionic type.