Photochemical Synthesis of Benzopinacol and Its...

Photochemical Synthesis of Benzopinacol and its Acid-Catalyzed Rerrangement Product Benzopinacolone M.E.G. Balita Institute of Chemistry, University of Philippines, Diliman, Quezon City Date Performed: February 18, 2011 Date Submitted: March 4, 2011 Abstract In this experiment it is aimed to synthesize benzopinacol through photochemical reaction of benzophenone and, benzopinacolone via acid-catalyzed rearrangement of benzopinacol. In this experiment, mixture of benzophenone, isopropyl alcohol and a drop of glacial acetic acid was exposed to sunlight which in turn, undergone photochemical reaction. In this reaction, molecules of benzophenone was brought to n((* triplet state where it possibly abstracted hydrogen from isopropyl†¦show more content†¦Then, a shift is observed by one of the atoms to the carbocation. And finally, to stabilize the molecule, catalyst is then regenerated to yield the final product. In this experiment, benzopinacol is to be synthesized through photochemical reaction from benzophenone and benzopinacolone via acid-catalyzed rearrangement of benzopinacol. II. Methodology In this experiment, benzopinacol was to be synthesized through photochemical reaction and its acid-catalyzed rearrangement product benzopinacolone. Synthesis of Benzopinacol In this synthesis, 2.0g of benzophenone was dissolved in 50ml isopropyl alcohol in 50ml Erlenmeyer flask. In this solution, one drop of glacial acetic acid was added. It was then filled with isopropyl alcohol up to the brim. After, the flask was stoppered using a well-rolled cork. It was ensured that very little air as possible was trapped inside the flask. It was tightly bind using a parafilm. The flask was inverted and exposed to sunlight outside the laboratory. After all additional product ceased to form, the reaction mixture was cooled in an ice bath to allow precipitation of benzopinacol. The final product was then filtered off from the solution using a Buchener funnel. Its melting point, yield and infrared spetrum was then obtained. The Acid-Catalyzed Rearrangement of Benzopinacol In this synthesis, in a test tube, 2.5ml of glacial acetic acid