Which sequence is the best route to m-nitrobenzoic acid from benzene?

A $HNO X_{3}$ / $H X_{2} SO X_{4}$ ; then $CH X_{3} Cl$ / $AlCl X_{3}$ ; then hot $KMnO X_{4}$ / $H X^{+}$
B $Cl X_{2}$ / $FeCl X_{3}$ ; then $HNO X_{3}$ / $H X_{2} SO X_{4}$ ; then hot $KMnO X_{4}$ / $H X^{+}$
C $CH X_{3} Cl$ / $AlCl X_{3}$ ; then $HNO X_{3}$ / $H X_{2} SO X_{4}$ ; then hot $KMnO X_{4}$ / $H X^{+}$
D $CH X_{3} Cl$ / $AlCl X_{3}$ ; then hot $KMnO X_{4}$ / $H X^{+}$ ; then $HNO X_{3}$ / $H X_{2} SO X_{4}$

Answer: D

The

- COOH

group must be present before nitration so that it directs meta: toluene, then benzoic acid, then m-nitrobenzoic acid. Nitrating toluene first gives o/p products (p-nitrobenzoic acid after oxidation). Friedel-Crafts alkylation on nitrobenzene fails, and the chloro route has no carbon substituent to oxidise.

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Which sequence is the best route to m-nitrobenzoic acid from benzene?

Answer: D

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