Question

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

The molar mass of the product (A) is        g mol−1. (Given molar mass in g mol−1 of C: 12,
H: 1, O: 16, Br: 80, N: 14, P: 31)

Hint:

In organic reactions, always ensure you track the structural changes in the molecule and calculate the molecular weights based on the atoms involved in the product.

Answer 1

The sequence of reactions involves the following steps:
1. The first step is the bromination of nitrobenzene (CH3C6H4NO2) with Br2 and Fe, leading to the formation of bromo nitrobenzene. 
2. In the second step, the nitro group (NO2) is reduced by Sn and HCl to form an amine group (NH2), resulting in the formation of aniline (CH3C6H4NH2). 
3. The third step involves diazotization of aniline using NaNO2 and HCl at 273K, which forms the diazonium salt.
4. The fourth and final step is the reaction of the diazonium salt with H3PO2 and H2O, which results in the formation of 4-bromo-1-methylbenzene (C7H7Br). Now, let's calculate the molar mass of the final product (C7H7Br):
The molar mass of C7H7Br is: \[ 7 \times 12 + 7 \times 1 + 80 = 171 \, \text{g/mol} \] Thus, the molar mass of the product is 171 g/mol.