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

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog (CIP) priority rules are a systematic method used to assign priorities to the groups attached to a stereocenter. By comparing the atomic numbers (or weights) of atoms directly attached to the chiral center, this system enables the determination of the molecule’s absolute configuration (R or S), which is essential for understanding its stereochemical properties.

Stereocenter

A stereocenter, often a carbon atom bonded to four distinct substituents, is the center in a molecule where the spatial arrangement of atoms leads to chirality. Identifying a stereocenter is crucial because it is the point at which different configurations (enantiomers) can exist, thereby affecting the molecule’s overall chemical behavior.

Chirality

Chirality refers to the characteristic of a molecule that enables it to exist in two non-superimposable mirror-image forms. This property is fundamental in stereochemistry and is responsible for differences in the biological activity of enantiomers, even though they share the same molecular formula.

Transcript

00:02 So in this problem, the question is asking to list to find the chiro center, and also it is asking to list the compounds in terms of priority.

00:15 So first, we're going to find the chiro center.

00:17 So again, we know that a chiro center is going to be a molecule that has a carbon in the middle and is surrounded by three different types of compounds.

00:26 Or, sorry, four different types of compounds, because the carbon is always going to have four compounds.

00:32 So first, the first compound, the first carbon we're going to look at is this one.

00:38 So we know that this carbon is attached to three hydrogens because it is terminal and there's nothing else attached to it.

00:46 So it's attached to three hydrogens.

00:47 And so since it's attached to three of the same exact types of molecules, this carbon cannot be a chiral center.

00:54 Now the next carbon we're going to look at is this one and this one is going to be attached to two hydrogens.

01:00 So since it's attached to two of the same types of molecules again, this one cannot be the chiro center.

01:07 The next one we're going to look at is this one.

01:09 And just like this, just like the one we just did, this one is also attached to two hydrogens.

01:15 So it cannot be the chiro center because it needs to have four different types of atoms attached.

01:20 Now, the last one in this molecule is this carbon.

01:24 And this carbon, it is the chiro center because it is attached to four different types of molecules.

01:29 Here it's attached to a hydrogen, here it's attached to a chlorine, here it's attached to a carbon that is attached to a chlorine and two hydrogen, and here it's attached to, basically, an ether.

01:45 It's attached, i mean, sorry, it's attached to a carbon and two hydrogens, and then a carbon and three hydrogens.

01:51 So it's an ethyl.

01:54 So this one is going to be the chiroc center, because it's attached.

01:59 Two, four different types of molecules.

02:01 So again, i'm going to label it chirocentre, so we know what the star means.

02:07 Now, the next part of the question is asking to label in terms of priority the four compounds that are attached to the chirocenter.

02:17 So the first thing we're going to do is look at this chlorine.

02:20 So this chlorine is attached directly to the carbon.

02:23 So it's going to have the greatest priority because this, there's only two things that are attached directly to the carbon.

02:29 When you're looking at priority of a chiro center, the first thing you want to look at is the molecules that are attached directly to the carbon.

02:36 Now, chlorine and between chlorine and hydrogen, obviously we know that chlorine has a higher priority because it weighs a lot more than hydrogen...

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