Chapter 8, Problem 34P

(a)

Interpretation Introduction

Interpretation:The indicated synthesis for alcohol should be evaluated as either good, not so good or worthless.

  

Concept introduction:Haloalkane solvolysis with ethanol, methanol or water is a typical example for unimolecuar substitution. It proceeds via two-step mechanism. The first slow step that determines rate is the removal of leaving group from the substrate haloalkane and generates a carbocation. Since the rate is only governed by substrate alone and no other nucleophile or solvent it is termed as unimolecuar substitution. The final step is attack of nucleophile on carbocation generated and formation of racemic products.

Tertiary or secondary halides undergo fastest unimolecuar substitution as they can readily form the tertiary carbocation followed by secondary and least reactive are primary.

(b)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be classified as either good, not so good or worthless.

  

Concept introduction:Bimolecular substitution or ${\text{S}}_{\text{N}}2$ proceeds via the single-step mechanism. Thus it is well known as the concerted mechanism. Nucleophile approaches carbon while the leaving group still departs from the rear side (opposite to leaving group). The transition state only illustrates the geometric orientation of the substrates and reagents as they pass through the maxima in the single-step mechanism.

A general ${\text{S}}_{\text{N}}2$ reaction mechanistic pathway is illustrated below:

  

(c)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be classified as either good, not so good or worthless.

  

Concept introduction:Bimolecular substitution or ${\text{S}}_{\text{N}}2$ proceeds via the single-step mechanism. Thus it is well known as the concerted mechanism. Nucleophile approaches carbon while the leaving group still departs from the rear side (opposite to leaving group). The transition state only illustrates the geometric orientation of the substrates and reagents as they pass through the maxima in the single-step mechanism.

A general ${\text{S}}_{\text{N}}2$ reaction mechanistic pathway is illustrated below:

  

(d)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be classified as either good, not so good or worthless.

  

Concept introduction: Bimolecular substitution or ${\text{S}}_{\text{N}}2$ proceeds via the single-step mechanism. Thus it is well known as the concerted mechanism. Nucleophile approaches carbon while the leaving group still departs from the rear side (opposite to leaving group). The transition state only illustrates the geometric orientation of the substrates and reagents as they pass through the maxima in the single-step mechanism.

A general ${\text{S}}_{\text{N}}2$ reaction mechanistic pathway is illustrated below:

  

(e)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be classified as either good, not so good or worthless.

  

Concept introduction: Bimolecular substitution or ${\text{S}}_{\text{N}}2$ proceeds via the single-step mechanism. Thus it is well known as the concerted mechanism. Nucleophile approaches carbon while the leaving group still departs from the rear side (opposite to leaving group). The transition state only illustrates the geometric orientation of the substrates and reagents as they pass through the maxima in the single-step mechanism.

A general ${\text{S}}_{\text{N}}2$ reaction mechanistic pathway is illustrated below:

  

(f)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be classified as either good, not so good or worthless.

  

Concept introduction: Bimolecular substitution or ${\text{S}}_{\text{N}}2$ proceeds via the single-step mechanism. Thus it is well known as the concerted mechanism. Nucleophile approaches carbon while the leaving group still departs from the rear side (opposite to leaving group). The transition state only illustrates the geometric orientation of the substrates and reagents as they pass through the maxima in the single-step mechanism.

A general ${\text{S}}_{\text{N}}2$ reaction mechanistic pathway is illustrated below:

  

(g)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be evaluated as either good, not so good or worthless.

  

Concept introduction: Haloalkane solvolysis with ethanol, methanol or water is a typical example for unimolecuar substitution. It proceeds via two-step mechanism. The first slow step that determines rate is the removal of leaving group from the substrate haloalkane and generates a carbocation. Since the rate is only governed by substrate alone and no other nucleophile or solvent it is termed as unimolecuar substitution. The final step is attack of nucleophile on carbocation generated and formation of racemic products.

Tertiary or secondary halides undergo fastest unimolecuar substitution as they can readily form the tertiary carbocation followed by secondary and least reactive are primary.

(h)

Interpretation Introduction

Interpretation: The indicated synthesis for alcohol should be classified as either good, not so good or worthless.

  

Concept introduction: Bimolecular substitution or ${\text{S}}_{\text{N}}2$ proceeds via the single-step mechanism. Thus it is well known as the concerted mechanism. Nucleophile approaches carbon while the leaving group still departs from the rear side (opposite to leaving group). The transition state only illustrates the geometric orientation of the substrates and reagents as they pass through the maxima in the single-step mechanism.

A general ${\text{S}}_{\text{N}}2$ reaction mechanistic pathway is illustrated below: