The product obtained when methylamine (CH₃NH₂) is treated with nitrous acid is:

Explanation :

• CH3NH2 is primary alkyl amine and undergoes reaction with HNO2 to give methanol in the following manner.

• The reaction takes place at very low temperatures of about 00 - 50C.
• The intermediate is methyldiazonium, which upon hydrolysis gives methanol.
• Nitrogen is also produced as a side product.

Hence, Methyl amine reacts with nitrous acid to give ethanol.

Important PointsThe reaction of primary amines with nitrous acid:

• Primary aliphatic amines react with nitrous acid to form alkyl diazonium salts.
• They on decomposition yields nitrogen gas and a carbocation.
• The reaction happens even at very low temperatures of about 5 degrees.
• The carbocation yields a mixture of alkene, alcohol, and alkyl halide by loss of a proton, reaction with H2O, and reaction with halide anions respectively.

The reaction of secondary amines with nitrous acid:

• Secondary amines do not form diazonium salts with nitrous acid and thus no liberation of nitrogen occurs.
• They react with nitrous acid to yield a yellow oily substance called nitroso amines.

​The reaction of tertiary amines with nitrous acid:​

• Tertiary aliphatic amines dissolve in cold nitrous acid to form salts which on warming decompose to give alcohol and nitroso amines.
• No liberation of nitrogen occurs.

Additional Information

Tertiary amines will not liberate N2 with HNO2.