Final answer:
The leaving group in the conversion from cyclohexanol to cyclohexanone is a water molecule, as the -OH group gets protonated under acidic conditions, making it a good leaving group.
Step-by-step explanation:
The leaving group in the conversion of cyclohexanol to cyclohexanone is a water molecule (H2O). This reaction involves the dehydration of cyclohexanol, which typically requires an acid catalyst like sulfuric acid. The -OH group is a poor leaving group and does not leave as a hydroxide ion. Instead, a proton from the acid catalyst protonates the hydroxyl group, transforming it into water (a good leaving group), which can then leave, facilitating the formation of the cyclohexanone.