Detergents are cleaning agents, commonly made from synthetic resources such as petroleum fraction, hydrocarbon or coal. Detergents are sodium salts of sulphonic acids and they were developed during the Second World War due to the shortage of vegetable oils and animal fats. Detergent is a class of surfactant, which reduces the surface tension of the water to make it much harder to bind with water and more likely to contact grease and oil.
(i) Cationic detergents
Cationic detergents are quaternary ammonium salts of chlorides, bromides or acetates. A cationic component of these detergents consists of a long hydrocarbon chain and the nitrogen atom has a positive charge in it.
Examples: Cetyltrimethylammonium bromide is a popular cationic detergent and is used in hair conditioners.
(ii) Anionic detergents – Anionic detergent is a synthetic detergent in which a lipophilic hydrocarbon group of the molecule is an anion. A detergent molecule consists of a long hydrocarbon chain and a water-soluble negative ionic group i.e sodium salts of the long-chain sulfonated alcohols or hydrocarbons.
Example: Sodium alkyl sulphates and Sodium alkyl benzene sulphonates.
(iii) Non-ionic detergents: They have no ions. They’re esters of high molecular mass alcohols.
Example: Can be prepared by the reaction between stearic acid and polyethylene glycol.