Question

Which compound given below does not respond to Rochelle salt?

• A. $H_{2}CO$
• B. $C_6{H}_{5}CHO$
• C. $C{H}_3-CH\left(OH\right)-CO-C{H}_3$
• D. $C{H}_{3}CHO$

Answer 1

Answer: (B), (C)

$C{H}_3-CH\left(OH\right)-CO-C{H}_3$

Aliphatic aldehyde on warming with Fehling solution solution give a red precipitate of cuprous oxide. The reaction is as follow:

Ketone and aromatic aldehyde does not respond to Fehling test.
$HCOOH$ and terminal $\alpha$-hydroxy ketone responds to Fehling test.

Compound (c) is $\alpha$-hydroxy ketone but it is not terminal, hence, it does not give Fehling test.
Hence, (b) and (c) are correct answers.