Amines · Question 38

Given below are some nitrogen containing compounds : [figure] Each of them is treated with HCl separately. 1.0 g of the most basic compound will consume mg of HCl. (Given molar mass in g mol-1 C : 12, H : 1, O : 16, Cl : 35.5)

Answer

341

Solution

In p-nitroaniline, aniline and acetanilide the lone pair on N is delocalised into the ring (and into C=O in acetanilide; -NO2 withdraws it further), so they are weak bases.

In benzylamine (C6H5CH2NH2) the -NH2 group is attached to an sp3 carbon; its lone pair is not delocalised.

Benzylamine is the most basic compound.

C6H5CH2NH2 + HCl C6H5CH2NH3+Cl- (1 : 1)

Molar mass of C7H9N = 84 + 9 + 14 = 107 g mol-1

Moles in 1.0 g = 1.0107 mol

Mass of HCl = 1.0107 36.5 g

= 0.3411 g 341 mg

Answer: 341