TiO₂ photocatalytic reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H₂O: incorporation effect of nanometer-sized Ag particles

Abstract

A highly endothermic reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H₂O selectively proceeds using TiO₂ as a photocatalyst, being significantly enhanced upon incorporation of nanometer-sized Ag particles on TiO₂.

References

1. S. Oae, Organic Chemistry of Sulfur, Plenum, New York, 1977.
2. T. P. Johnston and R. D. Elliott, J. Org. Chem., 1967, 32, 2344.
3. TiO₂ particles (anatase, BET surface area = 8.1 m² g^–1, Ishihara Sangyo Co.) were used. Ag/TiO₂ was prepared according to S.-i. Nishimoto, B. Ohtani, H. Kajiwara and T. Kagiya, J. Chem. Soc., Faraday Trans. 1, 1983, 79, 2685 As particles of < 5 nm were observed to be dispersed on TiO₂ by transmission electron microscopy.
4. T. Ung, M. Giersig, D. Dunstan and P. Mulvaney, Langmuir, 1997, 13, 1773.
5. A. Ulman, Chem. Rev., 1996, 96, 1533 and references therein.
6. J. Y. Gui, F. Lu, D. A. Stern and A. T. Hubbard, J. Electroanal. Chem., 1990, 292, 245.
7. C. A. Widrig, C. Chung and M. D. Porter, J. Electroanal. Chem., 1991, 310, 335.
8. D. E. Eastman, Phys. Rev. B2, 1970, 1.
9. F. Lohaman, Z. Naturforsch., Teil A, 1967, 22, 843.
10. M. Graetzel, in Energy Resources through Photochemistry and Catalysis, Academic Press, New York, 1983.
11. For R'SH, two types of dissociative adsorption on coinage metals (M) are proposed [eqns. (2) and (3)](P. E. Laibinis, G. Whitesides, D. L. Allara, Y.-T. Tao, A. N. Parikh and R. G. Nuzzo, J. Am. Chem. Soc., 1991, 113, 7152)

    R′SH + M⁰→ R′S^–– M¹+½ H₂ (2)

    R′SH + M¹→ R′S^–– M¹+ H⁺ (3)

    In the case of RSSR, homolytic dissociated adosrption appears to be plausible [eqn. (4)].

    RSSR + 2M⁰→ 2R′S^–– M¹ (4)

    .
12. R. Hoffmann, A Chemist's View of Bonding in Extended Structures, VCH, New York, 1993.
13. G. K. Jennings and P. E. Labinis, J. Am. Chem. Soc., 1997, 119, 5208.
14. T. Sakata, T. Kawai and K. Hashimoto, Chem. Phys. Lett., 1982, 88, 50.
15. J. B. Schlenoff, M. Li and H. Ly, J. Am. Chem. Soc., 1995, 117, 12528.