Chapter 21, Problem 21.45P

Interpretation Introduction

(a)

Interpretation:

The complete, detailed mechanism and the major organic product of the given reaction are to be drawn.

Concept introduction:

Acid chlorides are the least stable of carboxylic acid derivatives. Therefore, they serve as a useful starting material for the synthesis of other acid derivatives.

Carboxylic acids can be converted to the corresponding acid chlorides by treating them with ${\text{SOCl}}_{\text{2}}$ or ${\text{PCl}}_3$. The sulfur atom in ${\text{SOCl}}_{\text{2}}$ and the phosphorus atom in ${\text{PCl}}_3$ are both electrophilic as they are bonded to three highly electronegative atoms.

${\text{SOCl}}_{\text{2}}$ has the advantage that the by-products of the reaction, ${\text{SO}}_{\text{2}}$ and HCl, are both gases. They leave the solution, driving the reaction toward completion.

The reaction consists of two successive nucleophilic addition-eliminations. In the first of these, the reactant acts as the nucleophile and adds to the electrophilic sulfur of ${\text{SOCl}}_{\text{2}}$, eliminating a chloride. In the second reaction, the chloride ion from the first reaction acts as the nucleophile and adds to the electrophilic carbon that is bonded to the $-\text{OS(=O)Cl}$ group.

Interpretation Introduction

(b)

Interpretation:

The complete, detailed mechanism and the major organic product of the given reaction are to be drawn.

Concept introduction:

Acid chlorides are the least stable of carboxylic acid derivatives. Therefore, they serve as useful starting material for the synthesis of other acid derivatives.

Carboxylic acids can be converted to the corresponding acid chlorides by treating them with ${\text{SOCl}}_{\text{2}}$ or ${\text{PCl}}_3$. The sulfur atom in ${\text{SOCl}}_{\text{2}}$ and the phosphorus atom in ${\text{PCl}}_3$ are both electrophilic as they are bonded to three highly electronegative atoms.

${\text{SOCl}}_{\text{2}}$ has the advantage that the by-products of the reaction, ${\text{SO}}_{\text{2}}$ and HCl, are both gases. They leave the solution, driving the reaction toward completion.

The reaction consists of two successive nucleophilic addition-eliminations. In the first of these, the reactant acts as the nucleophile and adds to the electrophilic sulfur of ${\text{SOCl}}_{\text{2}}$, eliminating a chloride. In the second reaction, the chloride ion from the first reaction acts as the nucleophile and adds to the electrophilic carbon that is bonded to the $-\text{OS(=O)Cl}$ group.