Chapter 18, Problem 18.45P

Interpretation Introduction

(a)

Interpretation:

The mechanism and product for the given reaction are to be drawn.

Concept introduction:

The carbonyl carbon is electrophilic in nature due to the electronegativity difference. The nucleophile adds the electrophilic carbon of the carbonyl group. Since water is amphoteric in nature, it can act as acid as well as a base depending on availability and the reaction condition.

Interpretation Introduction

(b)

Interpretation:

The mechanism and product for the given reaction are to be drawn.

Concept introduction:

The carbonyl carbon is electrophilic in nature due to the electronegativity difference. The nucleophile adds the electrophilic carbon of the carbonyl group. Since water is amphoteric in nature, it can act as an acid as well as base depending on availability and the reaction condition. The $\text{α,β}$ unsaturated aldehyde or ketone possesses two electrophilic centers – one is carbonyl carbon itself and second is the $\text{β}$ carbon of the compound. Due to the resonance, there are two possible attacks for the nucleophile. When the nucleophile adds the carbonyl carbon, it is called a $\text{1, 2-addtion}$ product or direct addition product, and it is an irreversible addition as carbonyl group is not regenerated. Instead, alcohol is formed as the product on the acid or protic workup. When the nucleophile adds $\text{β}$ carbon of the carbonyl compound, it is called $\text{1, 4-addition}$ product or conjugate addition product, and it is a reversible addition as the carbonyl group is regenerated on the acid or protic workup.