Question
Arrange the following in increasing order of their basic strength in aqueous solution:
CH3NH2, (CH3)3N, (CH3)2NH
Solution
With the increase in the alkyl group, the +I effect will increase which will increase the ease of donation of lone pair electron. But in water one other factor is controlling the strength of basicity.
Amine will accept a proton and from cation will be stabilised in water by salvation (by hydrogen bonding) better the salvation by hydrogen bonding higher will be the basic strength.
(CH3)3N<CH3NH2< (CH3)2NH
