Which of the following molecules has an R configuration?
C) both a and b
D) neither a nor b

Question

Which of the following molecules has an R configuration?
C) both a and b 
D) neither a nor b

Quizplus · Accepted Answer

To determine the R or S configuration, we must look at the four substituents attached to the stereocenter and assign a priority to each based on the atomic number of the atom directly attached to the stereocenter. In molecule A, the substituents attached to the stereocenter are (in order of decreasing priority) carbon, carbon, hydrogen, and carbon. In molecule B, the substituents attached to the stereocenter are carbon, carbon, hydrogen, and fluorine. Since the highest priority substituent (carbon) is on the right side of the molecule in B, it has an R configuration. Therefore, the correct answer is B.

Which of the Following Molecules Has an R Configuration