Benzophenones photosensitization

Comparison of these experimental results with the calculated charge densities (S0 and Si) at the 2 and 3 positions (Table 11.5) shows that this is the expected result. Except for those compounds discussed below, the failure to observe quenching with triplet quenchers and reaction in the presence of a photosensitizer indicated singlet reactions. Compound (89) was found to also undergo benzophenone-photosensitized substitution, indicating that the triplet state of this compound is also reactive. The reaction, however, was less clean than that observed in the direct photolysis. Similarly, 1,6-dinitro-naphthalene was found to undergo both direct and benzophenone-photosensitized substitution ... 

Methylene has been prepared by the benzophenone-photosensitized decomposition of diazomethane.80 81 The mechanism is postulated to be... 

Cyclohexene. The experimental results are summarized in Table IV. The product ratios are similar for CH2 generated by CH2N2 photolysis and by CH2N2 pyrolysis at 265°C., but for CH2 generated by the benzophenone-photosensitized decomposition of CH2N2 the addition product norcarane is favored. 

Thermally unstable azetidines may be obtained by irradiation of furan in the presence of oxazolinones or 3-ethoxyisoindolone by [7r2s+ .2s] cycloaddition (Scheme 90) (75JA7298). Benzophenone photosensitized [ 2S+W2S] cycloaddition of furan to dimethylmaleic anhydride yields an adduct (34%). This reaction has been extended to 2,5-dimethylfuran and other maleic anhydrides and maleimides (76CA(84)120785). 

Moorthy PN, Hayon E (1975) Free-radical intermediates produced from the one-electron reduction of purine, adenine and guanine derivatives in water. J Am Chem Soc 97 3345-3350 Mori M, Teshima S-l, Yoshimoto H, Fujita S-l, Taniguchi R, Hatta H, Nishimoto S-l (2001) OH Radical reaction of 5-substituted uracils pulse radiolysis and product studies of a common redox-ambivalent radical produced by elimination of the 5-substituents. J Phys Chem B 105 2070-2078 Morin B, Cadet J (1995) Chemical aspects of the benzophenone-photosensitized formation of two lysine - 2 -deoxyguanosine cross-links. J Am Chem Soc 117 12408-12415 Morita H, Kwiatkowski JS,TempczykA(1981) Electronic structures of uracil and its anions. Bull Chem Soc Jpn 54 1797-1801... 

Moreover, benzophenone photosensitization with the seven-membered, 2-phenyl material succeeded, but relatively inefficiently. These are obviously only qualitative results and must be verified by careful quantum yield determinations. Nonetheless, the apparent order of reactivity in both direct and benzophenone-sensitized reactions is acyclioseven ring>six ring>five ring. (M. Tabet, W. Baik, Y.W. Wu, unpublished results, this laboratory). 

This reaction was reported for the benzophenone photosensitized degradation of polypropylene (92),polystyrene (95), poly(vinyl alcohol) (94),polyisoprene (95,96),polyurethane (97) and polyadenylic acid (98) In solid state benzophenone also produce an extensive crosslinking of polyethylene (99-105) It has also been found that benzophenone and its derivatives caused an initial rapid oxidation,increasing with ketone concentration (70) Currently the relative importance of singlet oxygen formation in energy transfer reaction between excited benzophenone and molecular oxygen is discussed (92,104) ... 

Benzophenone-photosensitized hydrolysis of CpFe(Cp—CR1=NR8) leads to the corresponding ketone or aldehyde CpFe(Cp—COR1).242 Photodecomposition of ferrocenyl ethers,243 and photochemical oxidation of ferrocene carboxylic acids on 254 nm irradiation have been discussed.244... 

Michler s ketone photosensitizer, coatings Isobutyl benzoin ether photosensitizer, graphic arts Isobutyl benzoin ether photosensitizer, inks Isobutyl benzoin ether photosensitizer, metal finishes Benzophenone photosensitizer, printing inks Benzophenone... 

Cuquerella MC, Lhiaubet-Vallet V, Cadet J, Miranda MA (2012) Benzophenone photosensitized DNA damage. Acc Chem Res 45 1558-1570... 

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