Total number of isomers (including stereoisomers) obtained on monochlorination of methylcyclohexane is ________.

To find the total number of isomers (including stereoisomers) obtained on monochlorination of methylcyclohexane, let's break down the problem step by step.

Methylcyclohexane Structure

Methylcyclohexane is a cyclohexane ring with a methyl group (-CH₃) attached to one of the carbon atoms in the ring. The methyl group can be attached in either axial or equatorial positions, which can lead to different conformations.

Monochlorination Reaction

When methylcyclohexane undergoes monochlorination, a chlorine atom replaces one of the hydrogen atoms on the carbon atoms in the ring.

Types of Positions for Chlorine Substitution

• Chlorine can be substituted at various positions around the cyclohexane ring.
• Since the methyl group can be attached in either the axial or equatorial position, we need to consider both possibilities.
• Chlorination can also happen in different positions relative to the methyl group, leading to different products.

Stereoisomers

Due to the possibility of axial and equatorial positions for the substituents and the symmetry of the cyclohexane ring, the chlorination can lead to stereoisomers. These are compounds that have the same molecular formula and connectivity but differ in the spatial arrangement of their atoms.

Counting the Isomers

• First, we need to count the different positions where chlorine can be attached.
• Then, consider the possibility of stereoisomers due to the different orientations (axial or equatorial) of the methyl group and chlorine.

After considering all the possible positions and stereoisomers, the total number of monochlorinated isomers of methylcyclohexane, including stereoisomers, is 12.

This includes all the distinct compounds that can result from monochlorination and their different spatial arrangements (cis-trans, axial-equatorial).