Consider the following reaction sequence [figure] The percentage of nitrogen in product 'T' formed is %. (Nearest integer) (Given molar mass in g mol-1 H : 1, C : 12, N : 14, O : 16)
Answer
20
Solution
Benzene conc. HNO3 + conc. H2SO4 P = nitrobenzene (C6H5NO2)
P [2. pH neutralised]1. Sn/HCl Q = aniline (C6H5NH2)
Q (CH3CO)2O R = acetanilide (C6H5NHCOCH3); acetylation reduces the activating effect of -NH2 and protects it from oxidation.
R conc. HNO3 + conc. H2SO4 S = p-nitroacetanilide (major, para because the bulky -NHCOCH3 group is o/p-directing)
S [2. pH neutralised]1. HCl/EtOH, T = p-nitroaniline (hydrolysis of the amide)
[figure]
T = C6H6N2O2; molar mass = 6(12) + 6(1) + 2(14) + 2(16) = 138 g mol-1
% N = 28138 100 = 20.29\% 20
Answer: 20