Chapter 2, Problem 53P

(a)

Interpretation Introduction

Interpretation: The energy associated with single $\text{H-H}$ eclipsed interaction should be determined.

Concept introduction: Various interconvertible forms that result from rotation around the $\text{C–C}$ bind in ethane are termed as conformer. To depict such conformation Newman projections are written. These are obtained by conversion of hashed-wedged line structure simply when molecule is viewed in a plane along the $\text{C–C}$ as illustrated below:

  

For example, energetics of rotation about the $\text{C–C}$ bond for $\text{2,3-dimethylbutane}$ is similar to the potential energy diagram of butane except for the added methyl groups at second and third carbon.

  

Because of relatively more bulkiness in the system compared to butane, the energy differences between the anti and all other conformations will increase, with the greatest increase at $180°$ .

(b)

Interpretation Introduction

Interpretation: The energy associated with single ${\text{CH}}_3\text{-H}$ eclipsed interaction should be determined.

Concept introduction: Various interconvertible forms that result from rotation around the $\text{C–C}$ bind in ethane are termed as conformer. To depict such conformation Newman projections are written. These are obtained by conversion of hashed-wedged line structure simply when molecule is viewed in a plane along the $\text{C–C}$ as illustrated below:

  

For example energetics of rotation about the $\text{C–C}$ bond for $\text{2,3-dimethylbutane}$ is similar to the potential energy diagram of butane except for the added methyl groups at second and third carbon.

  

(c)

Interpretation Introduction

Interpretation: The energy associated with single methyl-methyl eclipsed interaction should be determined.

Concept introduction: Various interconvertible forms that result from rotation around the $\text{C–C}$ bind in ethane are termed as conformer. To depict such conformation Newman projections are written. These are obtained by conversion of hashed-wedged line structure simply when molecule is viewed in a plane along the $\text{C–C}$ as illustrated below:

  

For example energetics of rotation about the $\text{C–C}$ bond for $\text{2,3-dimethylbutane}$ is similar to the potential energy diagram of butane except for the added methyl groups at second and third carbon.

  

(d)

Interpretation Introduction

Interpretation: The energy associated with single methyl-methyl gauche interaction should be determined.

Concept introduction: Various interconvertible forms that result from rotation around the $\text{C–C}$ bind in ethane are termed as conformer. To depict such conformation Newman projections are written. These are obtained by conversion of hashed-wedged line structure simply when molecule is viewed in a plane along the $\text{C–C}$ as illustrated below:

  

For example energetics of rotation about the $\text{C–C}$ bond for $\text{2,3-dimethylbutane}$ is similar to the potential energy diagram of butane except for the added methyl groups at second and third carbon.

  

Because of relatively more bulkiness in the system compared to butane, the energy differences between the anti and all other conformations will increase, with the greatest increase at $180°$ .