Question

Label each stereogenic center as R or S.

a.

b.

c.

d.

e.

f.

g.

h.

Short answer

a.

b.

c.

d.

e.

f.

g.

h.

Step-by-step solution

Location of a stereogenic center

To have a stereogenic center on a carbon atom, the carbon atom must be bonded to four different groups. The carbon atom with sp and hybridization is not considered.

The carbon having two hydrogen atoms is not considered. The larger organic molecules may have a large number of stereogenic centers.

Labeling of the stereogenic centers as R and S arrangements

• The priorities are assigned to the atoms which are directly bonded to the stereogenic carbon atoms.
• The atoms with the highest atomic number get the highest priority.
• The isotopes are prioritized based on decreasing mass numbers.
• The multiple bonds are treated as an equal number of single bonds.

R and S configurations for the given compounds

a. The structure below has one stereogenic center. It is the S isomer.

Representation of configuration of a

b. The structure below has one stereogenic center. It is the S isomer.

Representation of configuration of b

c. The structure below has one stereogenic center. It is the R isomer.

Representation of configuration of c

d. The structure below has two stereogenic centers. They both have R configuration.

Representation of configuration of d

e. The structure below has one stereogenic center. It is the R isomer.

Representation of configuration of e

f. The structure below has two stereogenic centers. They both have an S configuration.

Representation of configuration of f

g. The structure below has 2 stereogenic centers. They both have S configurations.

Representation of configuration of g

h. The structure below has 3 stereogenic centers. They all have S configuration.

Representation of configuration of h