Question

The structures of four isomers of an aldotetrose are given below.

Answer 1

Concepts and reason

The concept used to solve the problem is stereochemistry of the organic compound which have chiral center.

Fundamentals

In an organic compound, the compounds which have same molecular formula, similar connectivity but different orientation of the groups attached to the chiral carbon. Such isomers are known as stereoisomers.

The stereoisomers which have non-superimposable mirror images of one another are known as enantiomers.

The stereoisomers which are not a mirror image of each other are known as diastereomers.

Part 1

Molecular Formula of compound D is ${{\rm{C}}_4}{{\rm{H}}_8}{{\rm{O}}_4}$ and the connectivity is similar with A, B and C.

Attachment of groups at both chiral center must be different in the isomers.

Since B and D have different attachment of groups. So, they are also mirror images to each other. Hence, they are not diastereomers.

Attachment of groups at both chiral center must be different in the isomers.

Since A and D have different attachment of groups. So, they are not mirror images to each other. Hence, they are diastereomers.

Attachment of groups at both chiral center must be different in the isomers.

Since C and D have different attachment of groups. So, they are not mirror images to each other. Hence, they are diastereomers.

Part 2

Attachment of groups at both chiral center must be different in the isomers.

Since B and C have different attachment of groups. So, they are not mirror images to each other. Hence, they are not enantiomers.

Attachment of groups at both chiral center must be different in the isomers.

Since C and D have different attachment of groups. So, they are not mirror images to each other. Hence, they are not enantiomers.

Attachment of groups at both chiral center must be non-superimposable mirror images to each other in the isomers.

The structure A and C have non-superimposable mirror images to each other. Hence, they are enantiomers.

Part 3

Attachment of groups at both chiral center must different orientation to each other in the isomers.

Since A and C have different orientation to each other. Hence, they are stereoisomers.

Attachment of groups at both chiral center must be of different orientation in the isomers.

Since B and C have different orientation. Hence, they are stereoisomers.

Attachment of groups at both chiral center must be of different orientation in the isomers.

Since C and D have different attachment of groups. Hence, they are stereoisomers.

Ans: Part 1

The structure A and C are diastereomers of D.

Part 2

The structure A is enantiomers of C.

Part 3

The structure A, B and D are stereoisomers of C.