Question

Label each pair of compounds as constitutional isomers, stereoisomers, or not isomers of each other.

Short answer

1. Stereoisomers
2. Constitutional isomers
3. Not isomers of each other

4. Not isomers of each other

Step-by-step solution

Meaning of constitutional isomers and stereoisomers

Constitutional isomers are the structural isomers that have the molecular formula but differ from each other in terms of the connectivity between the various atoms.

Stereoisomers have the same order of bonding but differ from each other in terms of the three-dimensional arrangement of atoms in space.

Identification of each pair of compounds as constitutional and stereoisomers.

a. The following pair of compounds are the stereoisomers of each other.

A

Trans Isomer

B

Cis isomer

The above compounds are trans and cis isomers of each other. In the case of compound A, one of the groups is at the top, and the other is at the bottom, which means it is a trans isomer.

In compound B, both the groups are at the top, i.e., on the same side, which means it is a cis isomer.

b. The following pair of compounds are constitutional isomers.

The above two compounds have the same molecular formula${\text{C}}_7{\text{H}}_{14}$. These two compounds differ in terms of the connectivity of the two methyl groups.

c. The following pair of compounds are not isomers.

These two compounds have different molecular formulas.

d. The following two compounds are not isomers.

They have different molecular formulas.