(a) Ilustrate the following name reactions :
(i) Hell - Volhard - Zelinsky reaction
(ii) Wolff - Kishner reduction reaction
(b) How are the following conversions carried out :
(i) Ethylcyanide to ethanoic acid
(ii) Butan - 1-ol to butanoic acid
(iii) Methylbezene to benzoic acid

Explanation

(a) (i) Hell Volhard - Zelinsky Reaction : Carboxylic acids react with chlorine or bromine in the presence of phosphorous to give compounds in which d-hydrogen atom is replaced by nalogen atom.
`underset("acetic acid")(CH_(3)COOH+Cl_(2))overset("red P")tounderset("chloro acetic acid ")(Cl CH_(2) COOH + HCl)`
`Cl CH_(2) COOH + Cl_(2) overset("red P ") to underset ("Dichloro acetic acid" )(Cl_(2) CH COOH + CHl)`
`Cl_(2) CHCOOH+ Cl_(2) overset("red P") to underset("Trichloro acetic acid")(Cl_(3)C COOH + HCl)`
(ii) Wolff - Kishner reduction : The Carbonyl group of aldehydes and Ketones is reduced to `CH_(2)` group on treatment with hydrazine followed by heating with potassium hydroxide in high boiling solvent such as ethylene glycol.

(b) (i)
(ii) `underset("Butan - 1 - ol")(CH_(3)CH_(2) CH_(2)CH_(2)OH) underset("Oxidation[o]")overset(KmmO_(4)//KoH) to underset("Butanoic acid")(CH_(3)CH_(2)CH_(2)COOH)`
(iii)