JEE Advanced 2015 · Paper 2 · Chemistry Q22 · Dronacharya Exams

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ChemistryInteger+4Question 22 of 60

Among the following, the number of reaction(s) that produce(s) benzaldehyde is

Four reactions: I. benzene with CO, HCl, anhydrous AlCl₃/CuCl; II. benzal chloride (C₆H₅CHCl₂) with H₂O at 100 °C; III. benzoyl chloride with H₂, Pd-BaSO₄; IV. methyl benzoate with DIBAL-H in toluene at −78 °C, then H₂O.

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Answer and worked solution

Official answer: 4

All four reactions give benzaldehyde:

I. Gattermann-Koch formylation: CO, HCl, AlCl₃/CuCl.
II. Hydrolysis of benzal chloride: the gem-diol loses water.
III. Rosenmund reduction of benzoyl chloride.
IV. DIBAL-H at −78 °C reduces the ester to the aldehyde.

Answer: 4

Topics:Named reactions Oxidation and reduction

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