JEE Main · 2019 · 12 Jan 2019 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

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The aldehydes which will not form Grignard product with one equivalent Grignard reagents are:

(A)(b), (d)✓ Correct
(B)(b), (c)
(C)(b), (c), (d)
(D)(c), (d)

Answer: (A)

Solution

A Grignard reagent is destroyed by any acidic proton before it can add to a carbonyl. The aldehyde carrying a

- COOH

group and the one carrying a

- CH X_{2} OH

group each have such an acidic hydrogen, so a single equivalent of the reagent is used up in simple protonation rather than addition. These two therefore do not give the expected Grignard addition product.

JEE Main · 2019 · 12 Jan 2019 · Shift 2 · Single correct option

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