R or S? Stop Guessing. #chemistry #organicchemistry #studyhack

Ajouté : 2026-06-06

[00:00:00]So, what would be the correct stereo descriptor for the indicated carbon? Is it going to be an R or is it going to be an S molecule in front of us? Well, let's see. We have our carbon of interest right over here, and on the first level that carbon is connected to sulfur, carbon, carbon, and another carbon. At this point, we can say that sulfur is going to have the highest priority, so I'm going to give it number one right away. The carbon on top is connected to one carbon and a couple of hydrogens. The carbon on the bottom left is connected to one carbon, second carbon, and because of the double bond, we also have a phantom carbon. So, we're looking at three carbons. And the carbon on the right side is connected to real oxygen, phantom oxygen because of the double bond, and of course, we also have a hydrogen there as well. So, the second priority goes to this guy on the right, the third priority goes to the carbon on the bottom, and the last fourth priority goes on the top carbon. Since our lowest priority is not looking away from us, we would have to rotate that stereocenter in space, and the easiest way to do that is the double flip method that I teach in my stereochemistry videos. So, if you use that method, you will see that eventually we are going to end up with the S stereo descriptor. And if you don't know the double flip method that I'm talking about, make sure you check out the related video.