Experiment 6: Synthesis of Benzopinacolone A) Photoreductive Coupling of Benzophenone: O OH 2 OH OH O + + sun light 1,1,2,2-tetraphenyl-1,2-ethanediol 2-propanol (isopropyl alcohol) reducing agent reduced product oxidized product (benzopinacol) 1,1-diphenylmethanone 2-propanone (acetone) (benzophenone) Mechanism: Initiation: O O O S 1-diradical T 1-diradical intersystem crossing UV light Propagation: 31
1-diradical O OH H OH OH O H O OH O + + + + Termination: OH OH OH OH + A couple of drops of acetic acid are added because the glass can make the solution basic and cause a side reaction to occur. Ph 2 C O CPh 2 OH H Ph 2 C O CPh 2 OH HO Ph 2 C O Ph 2 C OH Ph 2 CH OH benzopinacol benzophenone diphenylmethanol + H OH ( Isopropyl alcohol is a flammable liquid ) ( Acetic acid is a corrosive liquid ) Question: Can tert-butyl alcohol be used instead of isopropyl alcohol in the synthesis of benzopinacol? Explain! B) Synthesis of Benzopinacolone (Pinacol Rearrangement)
This is the end of the preview. Sign up to
access the rest of the document.