Photocatalyzed titanium dioxide oxidation

Titanium dioxide photocatalyzed oxidation of neat tetralin was previously reported to give its hydroperoxide (14). Reinvestigation showed that tetralol and tetralone are also formed in acetonitrile possibly through electron transfer from tetralin to the positive holes (27). 

Titanium dioxide is widely used in the production of plastics, enamels, artificial fibers, electronic materials, and rubber (Hadjiivanov and Klissur-ski, 1996). Its ability to photocatalyze the oxidation of organic materials has been known for years in the paint industry. For this reason, TiOz is used as a white paint pigment (Stafford et al., 1996). TiOz is also known as an excellent catalyst for semiconductor photocatalysis due to its nonselectivity for environmental engineering applications it is nontoxic, insoluble,... 

Muszkat L, Feigelson L, Bir L, Muszkat KA. Titanium dioxide photocatalyzed oxidation of proteins in biocontaminated waters. J Photochem Photobiol B Biol 2001 60 32-6. 

Photocatalysis by semiconductor powders, most usually titanium dioxide, has been applied to the oxidation of several aromatics. In many such photocatalytic reactions, the key intermediates are hydroxyl radicals formed by oxidation of water. With rather good donors such as aromatic compounds, hole transfer on the excited semiconductor surface is a viable alternative in this case, the reaction of the radical cation of the substrate or further intermediates arising from it with oxygen or superoxide anion may have a role. Photocatalyzed oxidation of naphthalene yields 2-formyldrmamaldehyde and 1,4-naphthoquinone as the primary products (Eq. (45.16)), similarly to what occurs upon direct irradiation of naphthalene in water ... 

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