Question

Draw the structures for each compound.

1. (R)-3-methylhexane
2. (4R,5S)-4,5-diethyloctane
3. (3R,5S,6R)-5-ethyl-3,6-dimethylnonane
4. (3S,6S)-6-isopropyl-3-methyldecane

Short answer

a.

(R)-3-methylhexane

b.

(4R,5S)-4,5-diethyloctane

c.

(3R,5S,6R)-5-ethyl-3,6-dimethylnonane

d.

(3S,6S)-6-isopropyl-3-methyldecane

Step-by-step solution

The R and S configuration

The R and S configuration is used for the enantiomers of a compound. It is done by the identification of the chiral carbon atom in a compound.

The different groups on the chiral carbon atom are assigned priorities, and the isomers are named R or S based on that.

Labelling of R and S configuration

A curve is drawn from the first priority group on the chiral carbon to the third priority group. If the curve moves clockwise, then the chiral center is named as R. Similarly, if the curve moves anticlockwise, the chiral center is labeled as S.

The structure of the given compounds

a. R)-3-methylhexane

This compound has one stereocenter. It is an R isomer. The solid wedge shows the methyl group above the plane, whereas the hydrogen atom is below the plane.

(R)-3-methylhexane

b. (4R,5S)-4,5-diethyloctane

This compound has two stereocenters, as shown in the structure. One of the stereocenters has the R, and the other has the S configuration as marked in the structure.

(4R,5S)-4,5-diethyloctane

c. (3R,5S,6R)-5-ethyl-3,6-dimethylnonane

The given compound has three stereocenters as marked in the structure. Two centers have R configuration, and one has S.

(3R,5S,6R)-5-ethyl-3,6-dimethylnonane

d. (3S,6S)-6-isopropyl-3-methyldecane

The given compound has two stereocenters. Both of them have an S configuration.

(3S,6S)-6-isopropyl-3-methyldecane