Question

The correct order of increasing basic nature for the bases $NH_3 , CH_3 NH_2 $ and ${(CH_3)_2}NH$ in aqueous solutions aqueous solutions

• A. $ CH_3\,NH_2 <\, NH_3 <\, (CH_3)_{2} NH$
• B. $(CH_3)_2NH <\, NH_3 <\, CH_3 NH_2$
• C. $NH_3 <\, CH_3NH_2 <\, {(CH_3)_2 }NH $
• D. $CH_3\,NH_2 <\, {(CH_3)_2} NH < \,NH_3$

Answer 1

Answer: (C)

If the alkyl group is bigger than $CH _{3}$ group, there is steric hindrance to H-bonding and hence $+I$ effect predominates over H-bonding. $2>3>1$. There is an important role of the inductive effect, solvation effect and steric hindrane of alkyl group. Which decide the basic strength of alkyl amine in the aqueous state.

$(CH_3)_2NH > CH_3NH_2 > NH_3$