(i) Acetylation : Acetylation is the process of introducing an R−

O ||

C

− group in compounds that contain a replaceable hydrogen atom. The best example of acetylation is Friedel-Crafts acylation reaction where RCO group is introduced on thebenzene ring.1 Reagents employed for the purpose of acylation are acylchloride, acid anhydride etc. e.g., Friedel‑crafts acylation :(ii) Cannizzaro reaction : Cannizzaro reaction is undergone by aldehydes or ketones that lack an a-hydrogen atom. Such carbonyl compounds in the presence of conc. NaOH and heat undergo disproportionation reaction to produce the corresponding carboxylateion and alcohol.(iii)Cross-aldol condensation : Aldol condensation is the reaction that takes place, when aldehydes or ketones with at least one α-H atom react in the presence of dilute alkali to produce β- hydroxy aldehydes or ketones.
When two different aldehydesor ketones are taken, it gives a mixture of products. Such a reaction is called cross-aldol condensation.Ketones can also be used as one component in the cross aldol reactions(iv) Decarboxylation : Carboxylic acids lose carbon dioxide to form hydrocarbons when their sodium salts are heated with sodalime (NaOH and CaO in the ratio of 3 : 1). The reaction is