What are the R/S designations of the two stereocenters of L-threonine?

Question

Quizplus · Accepted Answer

The stereocenter at carbon 2 of threonine has the R configuration as its highest priority group (the carboxyl group) is on the right side of the molecule when oriented with the hydrogen atom at the back. The stereocenter at carbon 3 has the S configuration as its highest priority group (the hydroxyl group) is on the left side of the molecule when oriented with the hydrogen atom at the back. Therefore, the R/S designations for the two stereocenters are 2S,3R.

What Are the R/S Designations of the Two Stereocenters of L-Threonine