The line structure for pregabalin (Lyrica) is shown as follows:
Identify carbons a–d as primary, secondary, tertiary, or quaternary.

Question

The line structure for pregabalin (Lyrica) is shown as follows:

Line structure of pregabalin with labeled carbons a–d for identification as primary, secondary, tertiary, or quaternary.

Identify carbons a–d as primary, secondary, tertiary, or quaternary.

Accepted Answer

All right. Hi everyone. So this question is asking to determine whether each indicated carbon in the structure of isoleucine shown below is primary secondary tertiary or ordinary. And here we have four different carbons labeled in the structure of ISOL Lucy part A or option A says that one is secondary two is secondary three is secondary secondary and four is tertiary. B says that one is secondary two is tertiary, three is tertiary. And for a secondary C says that one is primary two is secondary, three is tertiary and four is secondary. And D says that one is primary, two is tertiary, three is secondary and four is tertiary. Now recall that a given carbon atom can be classified based on the number of other carbon atoms attached to it, right. So if we center our attention on a given carbon atom, that carbon atom is considered to be primary when there is one other carbon atom attached to it. And the classification here follows a very similar pattern from this point on right, because a secondary carbon is one that has two other carbon atoms attached. A tertiary carbon has three other carbon Adams attached, right? And a ordinary carbon is one that has four other carbon atoms attached, right. So let's focus our attention on the structure of isoleucine starting off with the carbon labeled one towards the left side of the structure. So focusing our attention on carbon one here will notice that there is only one other atom attached to carbon one, namely the carbon label two. So therefore, carbon one happens to be primary. So now we can go ahead and proceed with the adjacent carbon labeled number two. Now carbon two is connected to two other carbon atoms namely carbons one and three. So because of this, it is going to be secondary whereas carbon three is actually going to be tertiary, right? Because if we focus our attention on carbon three, we can see that there are three other carbons attached to it. There's carbon two attached to number three, there is carbon pho attached and also our methyl substituent. So that means that carbon three is tertiary and now we can focus our attention on carbon fork, right? Because carbon four is connected to two other carbons, namely the carbon label three and to the right side, the carbon of our carboxylic acid that is double bonded to oxygen and single bonded to another oxygen. So this means that the carbon labeled four is going to be secondary and there you have it based on this, our answer is going to be option c in the multiple choice because carbon one was primary. Carbon two was secondary, carbon three was tertiary and carbon four was secondary. So with that being said, thank you so very much for watching and I hope you found this helpful.

The line structure for pregabalin (Lyrica) is shown as follows:

Identify carbons a–d as primary, secondary, tertiary, or quaternary.

Verified video answer for a similar problem:

Key Concepts

Carbon Classification

Structural Representation

Functional Groups