Question

Consider three gaseous alkylamines A, B and C or 1°, 2° and 3° respectively. What will be the correct order of their basicity?

(a) A > B > C

(b) C > B > A

(c) B > A > C

(d) B > C > A

This question was addressed to me in unit test.

I need to ask this question from Amines Chemical Reactions topic in chapter Amines of Chemistry – Class 12

Answer 1

Right option is (b) C > B > A

The best explanation: In the gaseous state, the solvation effect is missing and hence the expected order of basicity will be 3° > 2° > 1°. This is because as the number of alkyl groups increase, the +I effect strengthens and more negative charge is accumulated on the N atom. This makes the unpaired share mire available for sharing with the proton of the acid.