Question

Complete the following reactions by writing the structure of the main products:

Hint:

Reduction reactions with hydrogen and palladium catalysts typically lead to the addition of hydrogen to double bonds, forming saturated products.

Answer 1

Reaction (I)

Reactants: Cyclohexanone and Semicarbazide (H₂NCONH–NH₂)

Reaction Type: Semicarbazone formation (nucleophilic addition-elimination with carbonyl compounds)

Product: Cyclohexanone semicarbazone

Structure of Product:

Cyclohexane ring – C=N–NH–CO–NH₂

This product is formed by the condensation of the carbonyl group (=O) with semicarbazide, where the =O is replaced by =N–NH–CO–NH₂.

Reaction (II)

Reactants: Dimethyl cadmium [(CH₃)₂Cd] and 2 molecules of acetyl chloride (CH₃COCl)

Reaction Type: Ketone synthesis using an organocadmium reagent

Product: 2 molecules of acetone (CH₃COCH₃)

Balanced Reaction:

(CH₃)₂Cd + 2 CH₃COCl → 2 CH₃COCH₃ (acetone) + CdCl₂

Reaction (III)

Reactants: Benzoyl chloride (C₆H₅COCl) and H₂ in the presence of Pd–BaSO₄

Reaction Type: Rosenmund reduction

Product: Benzaldehyde (C₆H₅CHO)

Mechanism: The acid chloride is selectively reduced to an aldehyde using hydrogen and a poisoned palladium catalyst (Pd–BaSO₄).

Summary of Products:

1. (I): Cyclohexanone semicarbazone
2. (II): Acetone (2 molecules)
3. (III): Benzaldehyde