Study Of Selective Oxidation Of Sulfide Oxidized By Air Under Mild Condition

Selective oxidation of sulfide is an important functional transformation in organic synthesis. At present, it has found a variety of catalytic system to achieve this transformation. But for the most of the oxidation system, there are a series of disadvantages such as poor selectivity, reaction conditions, by-products which might cause the environmental pollution, etc. This paper, for the first time, designs a catalytic oxidation system, which use PyHBr3, NBS as main catalyst, TBN, NaNO2as cocatalyst. Under mild conditions, sulfides can be oxidize to sulfoxide with air as oxidant. This paper built three catalytic oxidation system, which can efficient and high selectivity oxide a variety of sulfide substrate to sulfoxide.PyHBr3/TBN/H2O/air system, with phenyl methyl sulfide as the model substrates,3mol%of PyHBr3,4mol%of TBN,1mL H2O, under mild condition, sulfide can be oxidized to sulfoxide within3h, with a yield of91%.PyHBr3/NaNO2/H2O/air system, to a certain extent, replaced TBN by NaNO2improved the shortcoming of TBN, easy decomposition,5mol%of PyHBr3,5mol%of NaNO2,0.5mL H2O. Under this condition, thioether can convert into sulfoxide in3h, with a yield of90%.NBS/TBN/H2O/air system, using NBS as the main catalyst, TBN as cocatalyst, with3mol%of NBS,4mol%of TBN, under mild condition, phenyl methyl sulfide can convert to sulfoxide in3h, with a yield of91%.The above three catalytic systems respectively applied to the other aromatic sulfide and aliphatic sulfur ether, with a yield between71%-94%. For aromatic sulfides, substrates with electron-withdrawing groups take more time than those with electron-donating groups. At the same time this paper also illustrates the possible reaction mechanism of bromide and nitrogen oxide as the catalyst and cocatalyst. This paper, for the first time, realize selective oxidation of sulfide with air as oxidant under mild condition.