Why is configuration of this molecule S?

enter image source here

1 Answer
anor277
Jun 16, 2017

Because in terms of substituent priority, #Cl>Ph>Me>H#.

Explanation:

Normally we would use a model to assign stereochemistry; however, here, the representation of the molecule aids our assignment, and we can make the assignment unambiguously.

The substituent of LEAST priority goes BACK in to the page, and this #C-H# bond is our axis. Given the order of priority, we describe a circle around this axis, #Cl_1Ph_2Me_3#, and this circle proceeds in A COUNTERCLOCKWISE direction as we face this page, i.e. an #S# geometry.

Related questions
Impact of this question
524 views around the world
You can reuse this answer
Creative Commons License