In each of the compounds below, find the stereocenter, and label the four groups from 1 to 4 usi

In each of the compounds below, find the stereocenter, and...

Key Concepts

Stereocenters

A stereocenter, often called a chiral center, is an atom—typically a carbon—that is bonded to four different substituents. The presence of a stereocenter in a molecule gives rise to chirality, meaning the molecule and its mirror image are non-superimposable. Recognizing stereocenters is key for understanding the spatial arrangement of atoms in three-dimensional structures.

Cahn–Ingold–Prelog Priority Rules

The Cahn–Ingold–Prelog (CIP) priority rules are a systematic method used to assign priorities to the substituents attached to a stereocenter. Priorities are generally based on the atomic numbers of the atoms directly attached to the chiral center, with higher atomic numbers receiving higher priority. These rules ensure a standardized approach for determining the relative configurations of molecules.

Absolute Configuration Assignment

Absolute configuration refers to the spatial arrangement of the substituents around a stereocenter and is expressed using the R (rectus) or S (sinister) notation. Once the substituents have been prioritized using the CIP rules, the molecule is oriented so that the lowest priority group is positioned away from the observer, and the order of the remaining groups is analyzed to determine the configuration. This assignment is fundamental in distinguishing between enantiomers.

Transcript

00:03 So in this problem, the first part of the question is asking us to find the chiro center.

00:09 So we know that a chiro center is a carbon molecule that is surrounded by four different types of molecules.

00:16 So now we're going to look at the first possibility of the chiro center.

00:22 So now this carbon is the first possible chiro center.

00:26 So we are going to check.

00:27 So this carbon is attached to a ch3 over here.

00:31 We know that, let me do that in a different color.

00:33 So that it's better.

00:36 So we know that this carbon is attached to a ch3 over here and a ch3 over here.

00:42 So it cannot be the chiral center because it's attached to two of the same molecules.

00:47 So that is not the chiro center.

00:49 Now the next possible chiro center is going to be this carbon.

00:53 Now this carbon, again, is attached to a ch3 over here.

00:57 It's attached to a ch3 over here.

01:00 And this is also another ch3 molecule.

01:02 So this carbon, it cannot be the chiral center because it's attached to three of the same exact molecules.

01:09 Just as a recap, when you're drawing it in a line form, then a line like this is what represents a methyl group.

01:17 So this carbon is attached to three lines here, so it's attached to three methyl groups, and they're all the same.

01:24 So it cannot be a chiral center.

01:26 Now, let me give you one example of this molecule, which technically this is a carbon.

01:32 Right and it's attached to three hydrachines so this could we can look at this to make sure that it's not a chiral center so since it's attached let me get rid of this h3 right here so since it's attached to three of the same exact molecules these methyl groups that are like all over the molecule also cannot be chiro centers so now the only other carbon that is left is going to be this carbon now this carbon is attached to an oh over here, a hydrogen over here, one carbon over here, and one carbon over here.

02:08 This carbon is slightly different because this carbon is attached to three ch3 groups, while this carbon is attached to two ch3 groups and one hydroxy group...

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