Question

Question:Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?

Short answer

1. They are diastereomers,
2. They are identical
3. They are Constitutional isomers.
4. They are diastereomers,

Step-by-step solution

Definition of enantiomer, diastereomer, constitutional isomer

a) Identical: If a compound and its mirror image has exactly same structure,the compound is called identical.

b) Enantiomer: If a compound has a mirror image which is exactly opposite of the original compound, but don’t superimpose with each other is called enantiomers. Enantiomers also posses a plane of symmetry in a molecule.

c) Diastereomers: The compounds that has no mirror image, are non-identical and don’t superimpose with each other is known as diastereomers.

d) Constitutional isomer: The compounds that has same molecular formula but the connectivity through atoms in a bond are different and has no chiral centre are called constitutional isomers. They are also called structural isomers.

explanation of the answers

They are diastereomers.

From the numbering and structure, we can see all the 4 centres has same linkage , So, they are identical.

Here, in this picture, 1 and 3 position has same linkage but in the 1^st picture, substitute is in 5^th position whereas it is in 6^th position for the 2^nd picture. So, these two structures are constitutional isomers.