Explain: Acetylation.

(N/A) Acetylation is a specific type of acylation reaction where an acetyl group $(CH_3CO-)$ is introduced into an organic compound,typically an amine or alcohol.
In the context of amines,aliphatic and aromatic primary and secondary amines react with acetylating agents like acetyl chloride $(CH_3COCl)$ or acetic anhydride $((CH_3CO)_2O)$ via a nucleophilic substitution reaction to form $N$-substituted amides.
The reaction is generally carried out in the presence of a base,such as pyridine,which acts as an acid scavenger to remove the $HCl$ formed,thereby shifting the equilibrium to the right.
Example of acetylation of ethanamine:
$C_2H_5NH_2 + CH_3COCl \xrightarrow{\text{Pyridine}} C_2H_5NHCOCH_3 + HCl$
(Ethanamine + Acetyl chloride $\rightarrow$ $N$-Ethylethanamide + $HCl$)