The order of basic strength of the following in aqueous solution $$isNH3$$, $$C2H5NH2$$, $$(C2H5)2NH$$, $$(C2H5)3N$$

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 $$-CH3$$ group, there will be steric hindrance.Therefore, the change of the nature of alkyl group, i.e. from $$-CH3$$ to $$-C2H5$$ results in change in the order of basic strength.Thus, there is a subtle interplay of inductive effect, solvation effect and steric hindrance of alkyl group, which decides the basic strength of alkyl amines.

The order of basic strength of the following in aqueous solution $$isNH3$$, $$C2H5NH2$$, $$(C2H5)2NH$$, $$(C2H5)3N$$

(C 2 H 5 ) 2 NH > (C 2 H 5 ) 3 N > C 2 H 5 NH 2 > NH 3

(C 2 H 5 ) 3 N > (C 2 H 5 ) 2 NH > C 2 H 5 NH 2 > NH 3

(C 2 H 5 ) 2 NH > (C 2 H 5 ) 3 N > C 2 H 5 NH 2 > NH 3

(C 2 H 5 ) 3 N > C 2 H 5 NH 2 > (C 2 H 5 ) 2 NH > NH 3

NH 3 > H 2 NC 2 H 5 > N(C 2 H 5 ) 3 > HN(C 2 H 5 ) 2

Questions

The order of basic strength of the following in aqueous solution is
NH₃, C₂H₅NH₂, (C₂H₅)₂NH, (C₂H₅)₃N

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(C₂H₅)₃N > (C₂H₅)₂NH > C₂H₅NH₂ > NH₃

(C₂H₅)₂NH > (C₂H₅)₃N > C₂H₅NH₂ > NH₃

(C₂H₅)₃N > C₂H₅NH₂> (C₂H₅)₂NH > NH₃

NH₃ > H₂NC₂H₅ > N(C₂H₅)₃ > HN(C₂H₅)₂

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detailed solution

Correct option is B

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 -CH₃ group, there will be steric hindrance.
Therefore, the change of the nature of alkyl group, i.e. from -CH₃ to -C₂H₅ results in change in the order of basic strength.
Thus, there is a subtle interplay of inductive effect, solvation effect and steric hindrance of alkyl group, which decides the basic strength of alkyl amines.

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