Question

Q13 multiple option may be correct...

Answer 1

(b) is correct. This can be explain as follows- the basicity of amines increases as the electron donating alkyl group(+I effect) attched to it increases, because due to the +I effect of alkyl group the electron are pushes towards the nitrogen atom and availability of lone pair on nitrogen atom for donation increses and hence the basicity increases, basicity is define as the extent to which it can donate electrons. But in aqueous medium, due to the presence of water, the conjugate acid of amine may stabilized by the hydrogen bonding. This two factor namely- +I effect of alkyl group and hydrogen bonding, jointly determine the basicity of amines. Since in primary amines there are one alkyl group which have +I effect and its conjugate base has three hydrogen atom which can form hydrogen bond whereas ib tertiary amine there is 3 alkyl group which have +I effect and has only one hydrogen which can form hydrogen bond( AS SHOWN IN THE ATTACHED IMAGE). The formation of three hydrogen bond in conjugate acid of primary amine outweigh the + I effect of three methyl group in tertiary amine. Again more stable is the conjugate acid of base more basic is that base. Therefore primary amine is more basic than tertiary one.
[ secondary amine is the strongest base since it has 2 alkyl group having +I effect and 3 hydrogen atom which can form hydrogen bond]