Describe the method for the preparation of carboxylic acids from nitrogen-containing compounds (nitriles) with suitable examples.

(N/A) Carboxylic acids can be prepared from nitriles $(R-CN)$ through hydrolysis.
$1.$ Hydrolysis of Nitriles:
Nitriles are first hydrolyzed to amides in the presence of $H^{+}$ or $OH^{-}$ catalysts,and then further hydrolyzed to carboxylic acids.
General Reaction:
$R-C \equiv N + H_2O$ $\xrightarrow{H^{+} \text{ or } OH^{-}} R-CONH_2$ $\xrightarrow{H^{+} \text{ or } OH^{-}, H_2O} R-COOH + NH_3$
$2.$ Preparation from Alcohols (via Nitriles):
Alcohols can be converted to alkyl halides,then to nitriles,and finally to carboxylic acids with one additional carbon atom.
Example:
$CH_3OH$ $\xrightarrow{PCl_3} CH_3Cl$ $\xrightarrow{KCN} CH_3CN$ $\xrightarrow{H^{+}, \Delta, H_2O} CH_3COOH$ (Ethanoic acid)
Note: The reaction can be stopped at the amide stage by controlling the reaction conditions.