Ethanamine into methanamine (ethylamine to methylamine)

Explanation: The structure of ethanamine is CH₃CH₂NH₂. To convert ethanamine into methanamine (the number of carbon atoms is decreasing from two carbon atoms to one carbon atom), first we need ethanamide ( amide group- RCONH2) and we can get acetamide from acetic acid. By oxidation of ethanol, we can get ethanoic acid.

Step 1: Convert Ethanamine into ethanol with the help of diazonium salt

Ethanamine (CH₃CH₂NH₂)reacts with NaNO₂ and HCl to give Diazonium salt (R--N₂⁺Cl^-) which undergoes hydrolysis to form ethanol.

Note: The diazonium salts or diazonium compounds are the class of organic compounds with general formula R−N₂⁺X⁻ where X is an organic or inorganic anion (for example, Cl^–, Br^–, BF₄^–, etc.) and R is an alkyl or aryl group. Hence, they have two nitrogen atoms with one being charged. Example - Benzenediazonium chloride (C₆H₅N₂⁺Cl^–)

Step 2: Convert ethanol to ethanoic acid by oxidation

Ethanol (CH₃CH₂OH) undergoes oxidation in the presence of strong oxidizing agent KMNO₄ to form ethanoic acid (CH₃COOH)

Step 3: Convert ethanoic acid into ethanamide (amide group)

Ethanoic acid (CH₃COOH) is treated with ammonia (in excess) to form ethanamide (CH₃CONH₂)

Step 4: Convert ethanamide into methanamine by Hoffman Bromamide Reaction

Ethanamide (CH₃CONH₂) is treated with alc.NaOH or KOH in the presence of bromine, it gives methanamine (CH₃NH₂ - final product) which has one carbon atom less than the ethanamide.