Consider the following sequence of reactions to produce major product (A) Molar mass of product (A) is \_\_\_\_ \(\mathrm{g} \mathrm{mol}^{-1}\). (Given molar mass in \(\mathrm{g} \mathrm{mol}^{-1}\) of \(\mathrm{C}: 12, \mathrm{H}: 1\), \(\mathrm{O}: 16, \mathrm{Br}: 80, \mathrm{~N}: 14, \mathrm{P}: 31)\)

JEE Main · 2025 · 23 Jan 2025 · Shift 1 · Compounds Containing Nitrogen

Consider the following sequence of reactions to produce major product (A)

Molar mass of product (A) is ____

g mol^{- 1}

.
(Given molar mass in

g mol^{- 1}

C : 12, H : 1

O : 16, Br : 80, N : 14, P : 31)

Answer: 171

Solution

The substrate is 4-nitrotoluene (1-methyl-4-nitrobenzene). Bromination with

B r_{2} /Fe

is controlled by the strongly activating methyl group, which directs the incoming bromine ortho to itself (positions ortho/para to the deactivating nitro group are disfavoured), giving 2-bromo-4-nitrotoluene.

Sn/HCl

reduces the nitro group to an amino group, giving 2-bromo-4-aminotoluene. Treatment with

NaN O_{2} /HCl

273 K

converts the aromatic primary amine into its diazonium salt, and

H_{3} P O_{2} / H_{2} O

then reductively replaces the diazonium group with hydrogen (deamination), leaving only the methyl and bromo substituents on the ring.

The major product (A) is 2-bromotoluene,

C_{7} H_{7} Br

:

Molar mass

= 7 (12) + 7 (1) + 80 = 84 + 7 + 80 = 171 g mo l^{- 1}

JEE Main · 2025 · 23 Jan 2025 · Shift 1 · Integer answer

Practise more: all JEE Main PYQs on Compounds Containing Nitrogen →

JEE Main · 2025 · 23 Jan 2025 · Shift 1 · Compounds Containing Nitrogen

Solution

More JEE Main questions on Compounds Containing Nitrogen