Explanation: To convert ethanoic acid into methanamine (CH₃NH₂), we need ethanamide (amide group-RCONH₂) and we can get ethanamide from ethanoyl chloride (acid chloride group- RCOCl).

Step-1: Convert ethanoic acid into ethanoyl chloride

Ethanoic acid (CH₃COOH) reacts with thionyl chloride (SOCl₂) or PCl₅ or PCl₃ to form ethanoyl chloride (CH₃COCl) by the replacement of OH group by Cl atom.

Step-2 Convert ethanoyl chloride into ethanamide

Ethanoyl chloride (CH₃COCl) reacts with ammonia (in excess) to form ethanamide (CH₃CONH₂) by removal of NH₄Cl

Step-3: Convert ethanamide into methanamine (Hoffman Bromamide reaction)

Ethanamide (CH₃CONH₂) is treated with an aqueous or ethanolic solution of potassium hydroxide (KOH) and bromine (Br₂), it gives ethanamine (CH₃NH₂-final product)

Note: Hoffman Bromamide Reaction is a reaction in which a primary amide is treated with an aqueous KOH or NaOH and bromine, it gives a primary amine which has one carbon atom less than the original amide.