Which statement is true about oxidation of secondary alcohols with common oxidants?

• A. They are oxidized to aldehydes
• B. They are oxidized to ketones
• C. They are not oxidizable
• D. They are oxidized to carboxylic acids

Answer: (B)

When we oxidize an alcohol, the outcome depends on how substituted the carbon bearing the hydroxyl group is. For a secondary alcohol, the carbon with the OH is attached to two carbon substituents, so oxidation converts that carbon into a carbonyl. This turns the molecule into a ketone of the form R-CO-R'. With common oxidants, secondary alcohols stop at this ketone stage, rather than continuing to higher oxidation states. In contrast, primary alcohols give aldehydes, and under stronger or longer oxidizing conditions can become carboxylic acids. Tertiary alcohols generally resist oxidation under typical conditions. So secondary alcohols are oxidized to ketones.