Question

Which of the following statements about primary amines is false ?

• A. Alkyl amines are stronger bases than aryl amines
• B. Alkyl amines react with nitrous acid to produce alcohols
• C. Aryl amines react with nitrous acid to produce phenols
• D. Alkyl amines are stronger bases than ammonia

Answer 1

The Correct Option is C

To determine which of the statements about primary amines is false, let's evaluate each option based on known chemical behavior:

1. Option 1: "Alkyl amines are stronger bases than aryl amines"
   • This statement is true. Alkyl amines are indeed stronger bases than aryl amines because the alkyl group donates electron density better through the +I effect (inductive effect), increasing the electron density on the nitrogen atom, thus making it a stronger base.
2. Option 2: "Alkyl amines react with nitrous acid to produce alcohols"
   • This statement is also true. When reacted with nitrous acid (HNO₂), alkyl amines typically form diazonium salts, which can decompose to form alcohols among other products.
3. Option 3: "Aryl amines react with nitrous acid to produce phenols"
   • This statement is false. Aryl amines, such as aniline, when reacted with nitrous acid at low temperatures, form diazonium salts. These diazonium salts can be involved in various reactions, but directly converting to phenols requires subsequent hydrolysis, especially under acidic conditions. However, direct reaction with nitrous acid does not produce phenols without further steps.
4. Option 4: "Alkyl amines are stronger bases than ammonia"
   • This statement is true. Alkyl amines are generally stronger bases than ammonia due to the electron-donating effect of the alkyl groups, which increases the electron density on nitrogen.

By analyzing all options, we conclude that the false statement is:

The correct answer is: "Aryl amines react with nitrous acid to produce phenols".