Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
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Photochemical Reductions of Benzil and Benzoin in the Presence of Triethylamine and TiO? Photocatalyst

  • Published : 2002.09.20
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Abstract

This paper reports the photochemical reduction of benzil 1 to benzoin 2 and the reduction of 2 to hydrobenzoin 4 in deoxygenated solvents in the presence of triethylamine (TEA) and/or TiO2. Without TEA or TiO2, the photolysis of 1 resulted in very low yield of 2. The presence of TEA or TiO2 increased the rate of disappearance of 1 and the yield of 2, which were further increased considerably by the presence of water. The photoreduction of 1 to 2 proceeds through an electron transfer to 1 from TEA or hole-scavenged excited TiO2 followed by protonation. In the reaction medium of 88 : 7 : 2 : 3 CH3CN/CH3OH/H2O/TEA with 2.5 $㎎/m{\ell}$ of TiO2, the yield of 2 was as high as 85 % at 50 % conversion of 1. The photolysis of 2 in homogeneous media resulted in photo-cleavage to benzoyl and hydroxybenzyl radicals, which are mostly converted to benzaldehyde. The reduction product 4 is formed in low yield through the dimerization of hydroxybenzyl radicals. The addition of TEA increased the conversion rate of 2 and the yield of 4 significantly. This was attributed to the scavenging effect of TEA for benzoyl radical to produce N,N-diethylbenzamide and the photoreduction of benzaldehyde in the presence of TEA. The ratio of $(\pm)$ and meso isomers of 4 obtained from the photochemical reaction is about 1.1. This ratio is the same as that from the photochemical reduction of benzaldehyde in the presence of TEA. In the TiO2-sensitized photochemical reduction of 2, meso-4 was obtained in moderate yield. The reduction of 2 to 4 proceeds through two consecutive electron/proton transfer processes on the surface of the photocatalyst without involvement of ${\alpha}-cleavage$. The radical 11 initially formed from 2 by one electron/proton process can also combine with hydroxy methyl radical, which is generated after hole trapping of excited TiO2 by methanol, to produce 1,2-diphenylpropenone after dehydration reaction.

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References

  1. Bunbury, D. L.; Wang, C. T. Can. J. Chem. 1968, 46, 1473. https://doi.org/10.1139/v68-243
  2. Bunbury, D. L. Chuang, T. T. Can. J. Chem. 1969, 47, 2045. https://doi.org/10.1139/v69-329
  3. Bunbury, D. L.; Chan, T. M. Can. J. Chem. 1972, 50, 2499. https://doi.org/10.1139/v72-402
  4. Ogata, Y.; Takagi, K.; Fujii, Y. J. Org. Chem. 1972, 37, 4026. https://doi.org/10.1021/jo00798a012
  5. Mukai, M.; Yamauchi, S.; Hirota, N. J. Phys. Chem. 1989, 93, 4411. https://doi.org/10.1021/j100348a009
  6. Mukai, M.; Yamauchi, S.; Hirota, N. J. Phys. Chem. 1992, 96, 3305. https://doi.org/10.1021/j100187a025
  7. Adam, W.; Oestrich, R. S. J. Am. Chem. Soc. 1993, 115, 3455. https://doi.org/10.1021/ja00062a008
  8. Adam, W.; Kita, F.; Oestrich, R. S. J. Photochem. Photobiol. A: Chem. 1994, 80, 187 https://doi.org/10.1016/1010-6030(93)01031-V
  9. Encinas, M. V.; Scaiano, J. C. J. Am. Chem. Soc. 1979, 101, 7740. https://doi.org/10.1021/ja00520a031
  10. Okutsu, T.; Ooyama, M.; Hiratsuka, H.; Tsuchiya, J.; Obi, K. J. Phys. Chem. A 2000, 104, 288. https://doi.org/10.1021/jp991562b
  11. Shen, T.; Zhao, Z.-G.; Yu, Q.; Xu, H.-J. J. Photochem. Photobiol. A: Chem. 1989, 47, 203. https://doi.org/10.1016/1010-6030(89)87066-2
  12. Lipson, M.; Turro, N. J. J. Photochem. Photobiol. A: Chem. 1996, 99, 93. https://doi.org/10.1016/S1010-6030(96)04399-7
  13. Sheehan, J. C.; Wilson, R. M.; Oxford, A. W. J. Am. Chem. Soc. 1971, 93, 7222. https://doi.org/10.1021/ja00755a017
  14. Lewis, F. D.; Lauterbach, R. T.; Heine, H.-G.; Hartmann, W.; Rudolph, H. J. Am. Chem. Soc. 1975, 97, 1519. https://doi.org/10.1021/ja00839a041
  15. Bantu, N. R.; Kotch, T. G.; Lees, A. J. Tetrahedron Lett. 1993, 34, 2039. https://doi.org/10.1016/S0040-4039(00)60340-4
  16. Fox, M. A.; Dulay, M. T. Chem. Rev. 1993, 93, 341. https://doi.org/10.1021/cr00017a016
  17. Li, Y. In Organic Photochemistry; Ramamurthy, V.; Schanze, K. S., Eds.; Marcel Dekker, Inc.: New York, 1997; p 295.
  18. Cuendet, P.; Gratzel, M. J. Phys. Chem. 1987, 91, 654. https://doi.org/10.1021/j100287a031
  19. Mahdavi, F.; Bruton, T. C.; Li, Y. J. Org. Chem. 1993, 58, 744. https://doi.org/10.1021/jo00055a033
  20. Park, K. H.; Joo, H. S.; Ahn, K. I.; Jun, K. Tetrahedron Lett. 1995, 36, 5943. https://doi.org/10.1016/0040-4039(95)01204-U
  21. Brezova, V.; Bla_kova, A.; Havlínova, S. B. J. Photochem. Photobiol. A: Chem. 1997, 107, 233.
  22. Ferry, J. L.; Glaze, W. H. Langmuir 1998, 14, 3551. https://doi.org/10.1021/la971079x
  23. Pace, A.; Buscemi, S.; Vivona, N.; Caronna, T. Heterocylces 2000, 53, 183. https://doi.org/10.3987/COM-99-8702
  24. Tada, H.; Teranishi, K.; Ito, S. Langmuir 1999, 15, 7084. https://doi.org/10.1021/la981728k
  25. Joyce-Pruden, C.; Pross, J. K.; Li, Y. J. Org. Chem. 1992, 57, 5087. https://doi.org/10.1021/jo00045a018
  26. Park, J. W.; Hong, M. J.; Park, K. K. Bull. Korean Chem. Soc. 2001, 22, 1213.
  27. Energy Resourcers through Photochemistry and Photocatalysis; Gratzel, M., Ed.; Academic Press: New York, 1983.
  28. Hoffmann, M. R.; Martin, S. T.; Choi, W.; Bahnemann, D. W. Chem. Rev. 1995, 95, 69. https://doi.org/10.1021/cr00033a004
  29. Navio, J. A.; Marchena, F. J. J. Photochem. Photobiol. A: Chem. 1991, 55, 319. https://doi.org/10.1016/1010-6030(91)87033-R
  30. Moser, J.; Gratzel, M. J. Am. Chem. Soc. 1983, 105, 6547. https://doi.org/10.1021/ja00360a003
  31. Bard, A. J.; Faulkner, L. R. Electrochemical Methods: Fundametnals and Applications; Wiley: 1980; p 701.
  32. Chandrasekaran, M.; Noel, M.; Krishan, V. J. Chem. Soc. Perkin Trans. 2 1992, 979.
  33. Brimble, M. A.; Robinson, S. G. Tetrahdron 1996, 52, 9553. https://doi.org/10.1016/0040-4020(96)00492-9

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