Question

determine the following as r or s.
a. r r
b. r s
c. s r
d. s s

Explanation:

Step1: Assign priorities

Assign priorities to the four groups attached to the chiral center based on atomic number. In both cases, assume higher - numbered atoms have higher priorities.

Step2: Determine direction for I

For structure I, when we arrange the groups in order of decreasing priority (1 - 2 - 3), we move in a clock - wise direction. So it is R.

Step3: Determine direction for II

For structure II, when we arrange the groups in order of decreasing priority (1 - 2 - 3), we move in a counter - clockwise direction. So it is S.

Answer:

B. R, S