Chapter 18, Problem 18.63P

Interpretation Introduction

(a)

Interpretation:

The major organic product and the complete detailed mechanism for the given reaction is to be drawn.

Concept introduction:

In a Wolff-Kishner reduction, the carbonyl ($\text{C=O}$) group of a ketone or aldehyde is converted to a methylene (${\text{CH}}_{\text{2}}$) group. The ketone or aldehyde is first treated with hydrazine (${\text{H}}_{\text{2}}{\text{NNH}}_{\text{2}}$), followed by heating under basic condition. The first reaction takes place under mildly acidic conditions, so the nucleophilic ${\text{NH}}_{\text{2}}$ remains uncharged and so does the carbonyl oxygen. The second reaction takes place under strongly basic conditions, so no strong acids should appear. The anion formed is stabilized by both resonance as well as inductive effects. After proton transfer, the stability of nitrogen gas heavily drives the reaction. The formation of nitrogen gas makes the reaction irreversible. According to Le Chatelier’s principle, the formation of nitrogen gas helps drive the formation of products.

Interpretation Introduction

(b)

Interpretation:

The major organic product and the complete detailed mechanism for the given reaction is to be drawn.

Concept introduction:

In a Wolff-Kishner reduction, the carbonyl ($\text{C=O}$) group of a ketone or aldehyde is converted to a methylene (${\text{CH}}_{\text{2}}$) group. The ketone or aldehyde is first treated with hydrazine (${\text{H}}_{\text{2}}{\text{NNH}}_{\text{2}}$), followed by heating under basic condition. The first reaction takes place under mildly acidic conditions, so the nucleophilic ${\text{NH}}_{\text{2}}$ remains uncharged and so does the carbonyl oxygen. The second reaction takes place under strongly basic conditions, so no strong acids should appear. The anion formed is stabilized by both resonance as well as inductive effects. After proton transfer, the stability of nitrogen gas heavily drives the reaction. The formation of nitrogen gas makes the reaction irreversible. According to Le Chatelier’s principle, the formation of nitrogen gas helps drive the formation of products.