JEE Main 2025 Jan 22 Shift 1, Chemistry Q25: Introduction to Mechanism of Organic Reaction

JEE Main2025Jan 22, Shift 1Chemistry

Consider the following sequence of reactions :

Molar mass of the product formed (A) is ________ g mol $^{- 1}$ .

Your answer

Solution

Sequence:

(i) Sn/HCl reduces nitrobenzene to aniline (C $_{6}$ H $_{5}$ NH $_{2}$ ).

(ii) NaNO $_{2}$ /HCl at 0 $^{\circ}$ C diazotises aniline to benzenediazonium chloride (C $_{6}$ H $_{5}$ N $_{2}^{+}$ Cl $^{-}$ ).

(iii) Cu $_{2}$ Cl $_{2}$ (Sandmeyer reaction) replaces $-$ N $_{2}^{+}$ with $-$ Cl, giving chlorobenzene (C $_{6}$ H $_{5}$ Cl).

(iv) Na in dry ether (Wurtz-Fittig coupling) couples two molecules of chlorobenzene to give biphenyl: C $_{6}$ H $_{5} -$ C $_{6}$ H $_{5}$ .

Molar mass of biphenyl $= 12 \times 12 + 1 \times 10 = 144 + 10 = 154$ g/mol.

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