Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Amines

Question:

Read the following passage and answer questions.

Greater is the stability of the substituted ammonium cation, stronger should be the corresponding amine as a base. Thus, the order of basicity of aliphatic amines should be: primary > secondary > tertiary, which is opposite to the inductive effect based order. Secondly, when the alkyl group is small, like $-CH_3$ group, there is no staric hinderance to H-bonding. In case the alkyl group is bigger than $-CH_3$ group, there will be steric hinderance to H-bonding. Therefore, the change of nature of the alkyl group, e.g., from $-CH_3$ to $-C_2H_5$ results in change of the order of basic strength. Thus, there is a subtle interplay of the inductive effect, solvation effect and steric hinderance of the alkyl group which decides the basic strength of alkyl amines in the aqueous medium.

Which among the following amines is most basic in aqueous medium?

Options:

$(C_2H_5)_2NH$

$(C_2H_5)_3N$

$C_2H_5NH_2$

$NH_3$

Correct Answer:

$(C_2H_5)_2NH$

Explanation:

The correct answer is Option (1) → $(C_2H_5)_2NH$