Question

Explain why methylamine is a stronger base than Ammonia ?

Hint:

In gas phase, basicity order is $3^\circ>2^\circ>1^\circ>\text{NH}_3$. In aqueous phase, solvation effects change this order, but all alkyl amines remain stronger than ammonia.

Answer 1

1. Basicity depends on the availability of the lone pair on the nitrogen atom to accept a proton.
2. In Methylamine (CH$_3$NH$_2$), the methyl group (-CH$_3$) is an electron-releasing group (has a +I effect).
3. This effect increases the electron density on the nitrogen atom, making the lone pair more available for donation compared to Ammonia (NH$_3$).
4. Additionally, the methylammonium ion formed after accepting a proton is stabilized by the +I effect of the methyl group, shifting the equilibrium forward.
Thus, Methylamine is more basic than Ammonia.