Chapter 5.1, Problem 5.3E

(a)

Interpretation Introduction

Interpretation:The natural products indicated should be identified as either chiral or achiral.

  

Concept introduction:

The enantiomers are identical chemical compounds that have a mirror-image relationship to each other while diastereomers do not hold mirror image relationships. The former are chiral and optically active while the latter can be chiral or achiral.

Four kinds of symmetry elements that may be present are tabulated as follows:

  $\begin{array}{ccc}\text{S}\text{.No}& \text{Symmetry element}& \text{Notatio}n\\ 1.& \text{Axis of symmetry}& C_n\\ 2.& \text{Plane of symmetry}& \sigma \\ 3.& \begin{array}{l}\text{Alternating axis of }\\ \text{symmetry}\end{array}& S_n\\ 4.& \text{Center of symmetry}& i\end{array}$

Presence of any symmetry element makes molecule achiral and optically inactive.

(b)

Interpretation Introduction

Interpretation: The three molecules that represent enantiomers of $\text{2-chlorobutane}$ and two that are its mirror images should be identified.

  

Concept introduction: The enantiomers are identical chemical compounds that have a mirror-image relationship to each other while diastereomers do not hold mirror image relationships. The former are chiral and optically active while the latter can be chiral or achiral.