(i) Sulfonation reactions : It is the reaction with sulfuric acid to introduce sulfonic (SO3H) group into a compound.
(ii) Hydrogenation: Hydrogenation may be defined as the chemical reaction of an organic with molecular hydrogen in the presences of a catalyst. It is a unit process by which an organic compound reacts with molecular hydrogen in the presences of catalyst.
1) Ethylene can be hydrogenated to ethane under pressure in the presence of Ni catalyst
2) Cyclohexane can be produced by hydrogenation of benzene at 150 oC using Ni catalyst
(iii) Esterification: The reaction of an alcohol with a carboxylic acid to produce an ester is termed as esterification
Example : Esterification of an acid such as acetic acid by an alcohol such as ethyl alcohol results in the production of ethyl acetate. Sulphuric acid and hydrochloric acids are the catalysts used for esterification.