Chapter 3.7, Problem 3.10P

(a)

Interpretation Introduction

Interpretation:

The configuration for an enantiomer of naproxen has to be assigned.

Concept Introduction:

Priority rules:

• Priorities based on atomic number

$\begin{array}{l}\stackrel{\text{-}\text{H,}{\text{-CH}}_{\text{3}}\text{,}{\text{-NH}}_{\text{2}}\text{,}\text{-OH,}\text{-SH,}\text{-Cl,}\text{-Br,}\text{-I}}{\to }\\ \text{Increasing}\text{priority}\end{array}$

• When priority cannot be assigned on the basis of the atoms bonded directly to the chiral center

$\begin{array}{l}\stackrel{{\text{-CH}}_{\text{2}}\text{H,}{\text{-CH}}_{\text{2}}{\text{CH}}_{\text{3}}\text{,}{\text{-CH}}_{\text{2}}{\text{NH}}_{\text{2}}\text{,}{\text{-CH}}_{\text{2}}\text{OH,}{\text{-CH}}_{\text{2}}\text{Cl}}{\to }\\ \text{Increasing}\text{priority}\end{array}$

• Atoms participating in a double or triple bond are considered to be bonded to an equivalent number of phantom atoms.

For example,

• Priority assignment is made at the first point of difference between groups (should not be based on the larger group).

(b)

Interpretation Introduction

Interpretation:

The percentage of R and S enantiomers in the mixture has to be given.

Concept Introduction:

Enantiomeric excess:

It is the difference betweenthe percentages of twoenantiomers in a given mixture.

$\text{Enantiomeric}\text{excess}\text{(ee)}\text{=}\text{\%}\text{R}\text{-}\text{\%}\text{S}$