Question

Strength of acid increases with the attachment of group showing -I effect and decreases with the attachment of group showing + I effect. Which of the following is correct sequence of basic strength in aqueous solution? 

(a) CH₃NH₂ < (CH₃)₂NH < (CH₃)₃N

(b) (CH₃)₂NH < CH₃NH₂< (CH₃)₃N

(c) (CH₃)₃N < (CH₃)₂NH < CH₃NH₂ 

(d) (CH₃)₃N < CH₃NH₂ < (CH₃)₂NH

Answer 1

Answer is : (d) (CH₃)₃N < CH₃NH₂ < (CH₃)₂NH

The basic character of the given compounds follows the following trend in aqueous solution.

(CH₃)₃N < CH₃NH₂ < (CH₃)₂NH

This is due to combined effects of steric, hindrance, solvation and +I - effect.