Oxidation of Secondary Alcohols

Secondary alcohols are oxidised by acidified potassium dichromate(VI) to ketones. The orange solution turns green.The C-OH carbon in a secondary alcohol carries one hydrogen atom. Oxidation removes this hydrogen and the hydrogen from the -OH group, forming a C=O double bond within the chain. The oxygen from [O] combines with the two hydrogens to form water:RCH(OH)R′ + [O] → RCOR′ + H₂OThe ketone is not oxidised further. That would mean breaking a C-C bond, which acidified dichromate(VI) cannot do. So there is no need to remove the product quickly: the mixture is usually heated under reflux to make sure all the alcohol reacts, and the ketone is then separated by distillation.Worked example: write an equation for the oxidation of butan-2-ol and name the product.
Butan-2-ol is CH₃CH(OH)CH₂CH₃. The -OH carbon becomes C=O:CH₃CH(OH)CH₂CH₃ + [O] → CH₃COCH₂CH₃ + H₂OThe product is butanone.The C=O group is on the same carbon that carried the -OH group, so the position number stays the same: pentan-3-ol gives pentan-3-one, and propan-2-ol gives propanone. Ketones are named with the suffix -one.Because ketones resist further oxidation but aldehydes do not, the two can be told apart by mild oxidising agents.