Chapter 24: Phenols

Oxidation of Phenols

Summary

• In general, phenols are more easily oxidised than simple alcohols.
• Oxidation can achieved by reaction with silver oxide (Ag₂O) or chromic acid (Na₂Cr₂O₇), or other oxidising agents.
• Particularly important are the oxidation of 1,2- and 1,4-benzenediol (pyrocatechol and hydroquinone, respectively) and their derivatives (see examples below):

• These types of systems are important in biological redox-systems such as coenzyme Q and vitamin K.
• Here's a closer look at the two one electron transfers that are believed to take place when hydroquinone is oxidised to benzoquinone

 

	Loss of a proton and an electron generates a phenoxy radical
	Loss of a second proton and a second electron completes the oxidation. Can you draw a curly arrow scheme that shows how the quinone may be formed from a diradical  ? ANSWER

• Oxidations of Alcohols

© Dr. Ian Hunt, Department of Chemistry