Compound (A), $\mathrm{C}_{8} \mathrm{H}_{9} \mathrm{Br}$, gives a white precipitate when warmed with alcoholic $\mathrm{AgNO}_{3}$. Oxidation of (A) gives a acid (B), $\mathrm{C}_{8} \mathrm{H}_{6} \mathrm{O}_{4}$. (B) easily forms anhydride on heating. Identify the compound (A).

JEE Main · 2013 · 07 Apr 2013 · Offline · Haloalkanes and Haloarenes

Compound (A),

C_{8} H_{9} Br

, gives a white precipitate when warmed with alcoholic

AgNO_{3}

. Oxidation of (A) gives a acid (B),

C_{8} H_{6} O_{4}

. (B) easily forms anhydride on heating. Identify the compound (A).

(A)(see structure)
(B)(see structure)
(C)(see structure)
✓ Correct
(D)(see structure)

Answer: (C)

Solution

Three clues pin down the structure. The white precipitate with alcoholic

AgNO X_{3}

marks a reactive benzylic bromide rather than an unreactive aryl bromide. Oxidation to

C X_{8} H X_{6} O X_{4}

, a benzene dicarboxylic acid, and the ease with which that acid loses water to an anhydride, point to the two acid groups sitting ortho to one another, as in phthalic acid. Working back, compound A is the ortho isomer,

o

-methylbenzyl bromide, whose benzylic

CH X_{2} Br

and ring methyl both oxidise to give phthalic acid.

JEE Main · 2013 · 07 Apr 2013 · Offline · Single correct option

Practise more: all JEE Main PYQs on Haloalkanes and Haloarenes →

JEE Main · 2013 · 07 Apr 2013 · Offline · Haloalkanes and Haloarenes

Solution

More JEE Main questions on Haloalkanes and Haloarenes