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Reactions of amines
Appears in
Concepts tested here
- Benzoylation of aniline
- Carbylamine reaction
- Reaction with nitrous acid
All Questions
2015 AIPMT-II 1 question
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The following reaction
is known by the name:Benzoylation of aniline with benzoyl chloride in the presence of aqueous NaOH is the Schotten–Baumann reaction.
2012 AIPMT-MAINS 1 question
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An organic compound ($C_3H_9N$) (A), when treated with nitrous acid, gave an alcohol and $N_2$ gas was evolved. (A) on warming with $CHCl_3$ and caustic potash gave (C) which on reduction gave isopropylmethylamine. Predict the structure of (A).
A gives an alcohol and $N_2$ with nitrous acid, so A is a primary aliphatic amine: $C_3H_7NH_2 \xrightarrow{HONO} C_3H_7OH + N_2$
A primary amine warmed with $CHCl_3$ and KOH gives an isocyanide (carbylamine reaction): $C_3H_7NH_2 \xrightarrow{CHCl_3/KOH} C_3H_7-N\overset{\rightarrow}{=}C$ (C)
Reduction of an isocyanide gives a secondary amine with an N-methyl group: $C_3H_7-NC \xrightarrow{reduction} C_3H_7-NH-CH_3$
The product is isopropylmethylamine, $(CH_3)_2CH-NH-CH_3$, so the $C_3H_7$ group is isopropyl.
A is isopropylamine, $(CH_3)_2CH-NH_2$.
2010 AIPMT-PRE 1 question
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Which of the following statements about primary amines is 'False'?Alkyl groups release electrons (+I effect) and increase the electron density on nitrogen, so alkyl amines are stronger bases than ammonia (true).
In aryl amines the lone pair on nitrogen is delocalised into the benzene ring, so they are weaker bases than alkyl amines (true).
Primary aliphatic amines react with nitrous acid to give unstable aliphatic diazonium salts, which decompose to alcohols with evolution of nitrogen: $RNH_2 + HNO_2 \rightarrow ROH + N_2 + H_2O$ (true).
Primary aromatic amines react with nitrous acid at 273–278 K to form arenediazonium salts, which are stable at this temperature: $C_6H_5NH_2 + NaNO_2 + 2HCl \rightarrow C_6H_5N_2^+Cl^- + NaCl + 2H_2O$. Phenol is not the product of this reaction.
Hence the false statement is that aryl amines react with nitrous acid to produce phenols.
