Chapter 7, Problem 59P

(a)

Interpretation Introduction

Interpretation: The predominant elimination mechanism when concentration of NaOCH₂CH₃is 0.01 M needs to be determined.

Concept Introduction: The elimination reaction of an alkyl halide with nucleophile results in the formation of corresponding alkenes. There are two mechanisms that is E1 and E2. The E1 reaction is 2-step reaction and results in the formation of a carbocation first. The step 2 involves the formation of alkene after removal of the alpha hydrogen present in the carbocation. In the E2 mechanism, direct attack of the nucleophile and removal of leaving group takes place on the hydrogen atom which is at alpha position to the leaving group.

The rate of E1 mechanism depends only on the concentration of haloalkane and it is represented as follows:

  $R_{E1}=K_{E1}\left[\text{haloalkane}\right]$

Similarly, rate of E2 mechanism depends on both concentration of haloalkane and base thus,

  $R_{E2}=K_{E2}\left[\text{haloalkane}\right]\left[\text{base}\right]$

(b)

Interpretation Introduction

Interpretation: The predominant elimination mechanism when concentration of NaOCH₂CH₃is 1.0 M needs to be determined.

Concept Introduction: The elimination reaction of an alkyl halide with nucleophile results in the formation of corresponding alkenes. There are two mechanisms that is E1 and E2. The E1 reaction is 2-step reaction and results in the formation of a carbocation first. The step 2 involves the formation of alkene after removal of the alpha hydrogen present in the carbocation. In the E2 mechanism, direct attack of the nucleophile and removal of leaving group takes place on the hydrogen atom which is at alpha position to the leaving group.

The rate of E1 mechanism depends only on the concentration of haloalkane and it is represented as follows:

  $R_{E1}=K_{E1}\left[\text{haloalkane}\right]$

Similarly, rate of E2 mechanism depends on both concentration of haloalkane and base thus,

  $R_{E2}=K_{E2}\left[\text{haloalkane}\right]\left[\text{base}\right]$

(c)

Interpretation Introduction

Interpretation: The concentration of base at which 50% of the starting material reacts following E1 mechanism and 50% by E2 mechanism needs to be determined.

Concept Introduction: The elimination reaction of an alkyl halide with nucleophile results in the formation of corresponding alkenes. There are two mechanisms that is E1 and E2. The E1 reaction is 2-step reaction and results in the formation of a carbocation first. The step 2 involves the formation of alkene after removal of the alpha hydrogen present in the carbocation. In the E2 mechanism, direct attack of the nucleophile and removal of leaving group takes place on the hydrogen atom which is at alpha position to the leaving group.

The rate of E1 mechanism depends only on the concentration of haloalkane and it is represented as follows:

  $R_{E1}=K_{E1}\left[\text{haloalkane}\right]$

Similarly, rate of E2 mechanism depends on both concentration of haloalkane and base thus,

  $R_{E2}=K_{E2}\left[\text{haloalkane}\right]\left[\text{base}\right]$