Thiol oxidative coupling catalysts in individual state and on silica surface were synthesized on the basis of Cu complexes with nitrogen containing ligands.  In the presence of all catalysts thiol is oxidized to the corresponding disulfide. All studied ligands [1-3] interact with the reaction substrate. The first group of catalysts consists of the ligands, possessing reducing properties (amines, aminoalcohols etc). Second group contains complexes with pyridine, dimethylformamide, imidazole, other heterocycles. These complexes interact with thiol even at the absence of oxygen (Table 1) [3]. By NMR-MAS in pyridine containing systems products of ligand hydrogenation were found. So ligands with oxidation properties should be used to obtain catalysts for thiol coupling at the absence of alkali, as opposed to widely used cobalt phthallocianines. Complex with monoethanolamine immobilised on the surface of silica gel through Si-O-C bonds is very active. Also high activity is shown by the immobilized complexes of Cu(II) with ionic liquids � propilpyridinium or ethylimidazolium chlorides. These complexes lose their activity because the silica gel surface adsorbs the thiol, it isolates catalytic centres from oxygen. Washing the inactive catalyst with the excess of isooctane restores the activity. Thus the studied complexes are perspective catalysts for oil sweetening. Ref.:  (1) Tarkhanova I.G.et al, - Reac. Kin., Mech. and Cat., 2010  , 101 (1), 267, (2) Tarkhanova I.G.et al, - Phosph., sulph. Sil. and the rel.el., in press., (3) Tarkhanova I.G.et al - Materials of 10th International Congress on Catalysis EuropaCat.

Catalysts for thiol oxidative coupling in non-aqueous media

243rd National Meeting (2012)

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