Each question in this section has four suggested answers of which ONE OR MORE answers will be correct. Which of the following compounds will give liberation of nitrogen gas when treated with \(\mathrm{NaNO}_{2}\) and \(\mathrm{HCl}\) at low temperature? (a) Benzylamine (b) N,N-Dimethylaniline (c) Diethylamine (d) Alanine

To analyze each compound, first identify the class of each amine (primary, secondary, or tertiary). This is important because diazonium salts are formed only from primary amines. (a) Benzylamine: This is a primary amine (R-NH₂), where R is the benzyl group. (b) N,N-Dimethylaniline: This is a tertiary amine (R₃N), where the nitrogen atom is bonded to three carbon groups (two methyl groups and one phenyl group). (c) Diethylamine: This is a secondary amine (R₂NH), where the nitrogen atom is bonded to two ethyl groups. (d) Alanine: This is an amino acid containing a primary amine group (NH₂) and a carboxylic acid group (COOH).

Based on the class of the amine and the formation of diazonium salts only through primary amines, we can analyze the reactivity of the given compounds as follows: (a) Benzylamine: Being a primary amine, it can react with \(\mathrm{NaNO}_{2}\) and \(\mathrm{HCl}\) at low temperature to form a diazonium salt and subsequently liberate nitrogen gas. (b) N,N-Dimethylaniline: As a tertiary amine, it cannot form a diazonium salt and will not liberate nitrogen gas when treated with \(\mathrm{NaNO}_{2}\) and \(\mathrm{HCl}\) at low temperature. (c) Diethylamine: As a secondary amine, it cannot form a diazonium salt and will not liberate nitrogen gas when treated with \(\mathrm{NaNO}_{2}\) and \(\mathrm{HCl}\) at low temperature. (d) Alanine: Although it contains a primary amine group, the presence of the carboxylic acid group (which can potentially form an amide upon reaction with the amine group) may complicate the reaction. However, under the specific reaction conditions of low temperature and the presence of \(\mathrm{HCl}\), alanine can still react with \(\mathrm{NaNO}_{2}\) to form a diazonium salt and subsequently liberate nitrogen gas.

Based on the analysis in the previous steps, we can conclude that the following compounds will liberate nitrogen gas upon reaction with \(\mathrm{NaNO}_{2}\) and \(\mathrm{HCl}\) at low temperature: (a) Benzylamine and (d) Alanine.