Question:

(a) Draw two different enol tautomers of 2-methylcyclohexanone.

(b) Draw two constitutional isomers that are not tautomers, but contain a $\mathbf{C}\mathbf{=}\mathbf{C}$ and an O-H group.

2-methylcyclohexanone

In organic chemistry, isomers are those compounds that have a similar number of atoms but have different physical and chemical properties. They have a different arrangement of atoms.

There are generally two types of isomers: structural isomers and stereoisomers.

Structural isomers or constitutional isomers are those which differ in connectivity of atoms in the compound.

There are 3 types of structural isomers: positional isomers, chain isomers, or functional group isomers.

Tautomerism is a special type of functional group isomerism in which isomers are in equilibrium with each other.

(a) Enol form of a ketone is obtained by removing hydrogen from alpha carbon.

2-methylcyclohexanone has a secondary alpha-carbon and a tertiary alpha-carbon. Removing hydrogen from each alpha-carbon, we get two enols. They are:

Two enol forms of 2-methylcyclohexanone

b) Constitutional isomers are compounds that have the same formula but different arrangements of atoms.

Two constitutional isomers of 2-methylcyclohexanone that are not enols can be given by:

Constitutional isomers of 2-methylcyclohexanone.