Consider the following sequence of reactions : (i) $\mathrm{Sn}+\mathrm{HCl}$ (see structure) (ii) $\mathrm{NaNO}_{2}, \mathrm{HCl}$ $\xrightarrow[\text { (iii) } \mathrm{Cu}_{2} \mathrm{Cl}_{2}]{0^{\circ} \mathrm{C}} \underset{\text { Product }}{\mathrm{A}}$ (iv) Na, Ether Molar mass of the product formed (A) is \_\_\_\_\_ $\mathrm{g} \mathrm{mol}^{-1}$.

JEE Main · 2025 · 22 Jan 2025 · Shift 1 · Compounds Containing Nitrogen

Consider the following sequence of reactions :
(i)

Sn + HCl

(see structure)
(ii)

NaNO_{2}, HCl

0^{\circ} C (iii) Cu_{2} Cl_{2} Product A

(iv) Na, Ether

Molar mass of the product formed (A) is
_____

g mol^{- 1}

Answer: 154

Starting from nitrobenzene, the sequence runs:

(i)

S n / H C l

reduces the nitro group to an amine: nitrobenzene

\to

aniline.

(ii)

N a N O_{2} / H C l

0^{\circ} C

diazotises the amine: aniline

\to

benzenediazonium chloride.

(iii)

C u_{2} C l_{2}

carries out a Sandmeyer reaction, replacing the diazonium group with chlorine: benzenediazonium chloride

\to

chlorobenzene.

(iv)

N a

, ether effects a Wurtz–Fittig coupling of two molecules of chlorobenzene, joining the two aryl groups directly:

2 C_{6} H_{5} C l + 2 N a e t h er C_{6} H_{5} - C_{6} H_{5} + 2 N a C l

The product A is biphenyl,

C_{12} H_{10}

, with molar mass

12 (12) + 10 (1) = 154

g/mol.

JEE Main · 2025 · 22 Jan 2025 · Shift 1 · Integer answer