Question

Identify the molecule having S configuration.

• A. A
• B. B
• C. C
• D. A and C both

Answer 1

The correct option is B B

Cases of R and S nomenclature
If the 4th (least) priority group is on the vertical position then clockwise direction from priority order 1 to 3 will be R.
If the 4th (least) priority group is on the vertical position then anti-clockwise direction from priority order 1 to 3 will be S.
If the 4th (least) priority group is on the horizontal position then clockwise direction from priority order 3 to 1 will be R.
If the 4th (least) priority group is on the horizontal position then anti-clockwise direction from priority order 3 to 1 will be S.
Hence B has S configuration.