Introduction:
Phenol (PhOH) and cyclohexanol (CyOH) are two organic compounds with similar chemical formulas but different structures. The presence of a hydroxyl group (-OH) in both compounds allows for the possibility of tautomerism, which is a phenomenon where isomers can interconvert by the movement of a hydrogen atom and a double bond. In this response, we will explore whether PhOH and CyOH exhibit tautomerism and explain the reasons behind it.

Tautomerism:
Tautomerism is a type of isomerism where two compounds can exist in equilibrium with each other by the migration of a hydrogen atom and a double bond. Generally, tautomerism occurs when a compound can undergo prototropic tautomerism, which involves the movement of a hydrogen atom between two different atoms.

Structure of Phenol:
Phenol (PhOH) is an aromatic compound consisting of a phenyl ring (C6H5) attached to a hydroxyl group (-OH). The hydroxyl group is directly bonded to the benzene ring, resulting in an sp2 hybridized carbon atom.

Structure of Cyclohexanol:
Cyclohexanol (CyOH) is an aliphatic compound with a cyclohexane ring and a hydroxyl group (-OH) attached to it. The hydroxyl group is bonded to a carbon atom that is part of the cyclohexane ring, resulting in an sp3 hybridized carbon atom.

Potential Tautomerism:
Phenol and cyclohexanol can potentially exhibit tautomerism because they both have a hydroxyl group (-OH) attached to a carbon atom. The hydroxyl group in both compounds can donate a hydrogen atom, resulting in the formation of a double bond with the adjacent carbon atom.

Difference in Stability:
Phenol is more acidic compared to cyclohexanol due to the resonance stabilization of the phenoxide ion formed upon deprotonation. The aromaticity of the phenyl ring stabilizes the negative charge, making it easier for phenol to lose a proton. On the other hand, cyclohexanol is less acidic because the cyclohexane ring does not provide aromatic stabilization.

Conclusion:
In conclusion, while both phenol and cyclohexanol have the potential to exhibit tautomerism, it is more likely to occur in phenol due to its greater stability as a phenoxide ion. The resonance stabilization of the phenoxide ion enhances the acidity of phenol and facilitates the movement of a hydrogen atom and a double bond. Cyclohexanol, on the other hand, is less likely to undergo tautomerism due to its lower acidity and lack of aromatic stabilization.