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? |
$(C_2H_5)_2NH$ $(C_2H_5)_3N$ $C_2H_5NH_2$ $NH_3$ |
$(C_2H_5)_2NH$ |
The correct answer is Option (1) → $(C_2H_5)_2NH$ |