Question

Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents:
i. PhMgBr and then H₃O⁺              ii. Tollen’s reagent
iii. Semicarbazide and weak acid   iv. Excess ethanol and acid
v. Zinc amalgam and concentrated hydrochloric acid

Answer 1

i. The reaction of cyclohexanecarbaldehyde with PhMgBr followed by acid hydrolysis gives an alcohol.

ii. Oxidation of cyclohexane carbaldehyde with Tollen’s reagent gives cyclohexane carboxylate ion.

iii. The reaction of cyclohexane carbaldehyde with semicarbazide and weak acid gives a semicarbazone.

iv. The reaction of cyclohexane carbaldehyde with excess ethanol and acid gives an acetal.

v. Zinc amalgam and concentrated hydrochloric acid reduces -CHO group to -CH₃ group (Clemmensen’s reduction).