Assign R or S configurations to the chirality centers in ascorbic acid (vitamin C).

Name: Problem 48, Chapter 5: Organic Chemistry
Uploaded: 2020-06-24T14:13:55-08:00
Duration: 3 min 58 s
Channel: Travis Maslanik
Description: Assign R or S configurations to the chirality centers in ascorbic acid (vitamin C).

step 1 So we have the following organic compound here. We have upscorific acid, otherwise known as vita

Assign R or S configurations to the chirality centers in...

Key Concepts

Chirality Centers

Chirality centers, often tetrahedral carbon atoms, are points in a molecule where the spatial arrangement of different substituents results in non-superimposable mirror images. This property is fundamental in stereochemistry and is critical in determining the molecule's biological activity and interactions.

R and S Configurations

The R (rectus) and S (sinister) descriptors indicate the absolute configuration of a chiral center. After assigning priorities to the substituents, these labels are used to describe the three?dimensional orientation of the groups attached to the chiral center, helping to differentiate enantiomers.

Cahn-Ingold-Prelog (CIP) Priority Rules

The CIP priority rules offer a systematic method to rank the substituents attached to a stereocenter based on atomic numbers and connectivity. By assigning these priorities, one can determine the configuration by observing the order in which the groups are arranged in space when the lowest priority is oriented away.

Absolute Configuration Assignment

This process involves orienting the molecule so that the substituent with the lowest priority is directed away from the observer, and then determining whether the sequence of the remaining substituents proceeds in a clockwise (R) or counterclockwise (S) direction. This assignment is crucial for understanding the stereochemical nature and reactivity of the molecule.

Transcript

00:01 So we have the following organic compound here.

00:03 We have upscorific acid, otherwise known as vitamin c.

00:07 And for this compound, we want to identify the chiral centers, as well as assign stereochemistry or configuration for age carol center.

00:18 So looking at the molecule, it looks like we have two different chiral centers here.

00:24 So one of them is going to be this here.

00:27 This one's quite easy to see.

00:28 We have the o.

00:30 We're bounded to the oxygen going towards us.

00:32 We have the hydrogen going away from us.

00:35 And then we have the left side of the chain, which is the cyclic structure.

00:39 And then we have the right side of the chain, which eventually goes to our ethanol.

00:44 So we have four different groups there, and therefore we can say that this is a different, or this is a chiral center.

00:50 And then we also have this one here.

00:54 So we have four different groups because we have our ethanol on the bottom right.

00:58 We have our alcohol group coming towards us, hydrogen group going away from us, and then the left side of the cyclic chain.

01:06 So we would say we have four different groups there.

01:08 And so for this compound, we are going to have two different chiral centers.

01:12 And now we want to assign a configuration for each one.

01:15 So looking at the chiral center that is green, i'm going to go ahead and sign priorities to each of our groups.

01:23 And so, of course, our directly bounded o is going to have the highest priority.

01:29 As it has the highest mass.

01:31 And then, so now we have this carbon here.

01:38 Right...

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