Question

Which one of the following major product formed on sulfonation of benzaldehyde with fuming sulfuric acid?

• A.
• B.
• C.
• D. (a) and (b) above.

Answer 1

The correct option is C

Sulphonation of benzaldehyde is the substitution of the hydrogen atom of benzaldehyde molecule by $-S{O}_{3}H$ (sulphonic acid) group.
$-CHO$ is the meta directing group because it is electron withdrawing group. It pulls the electron density towards itself and acts as a deactivating group on benzaldehyde ring which gives generally meta substituted $-S{O}_{3}H$ as a major product. Thus option (c) is correct.