Study Of Selective Oxidation Of Sulfides By Oxygen

The oxidation of sulfides to sulfoxides represents one of the most important functional group transformations in organic synthesis.Sulfoxides as a class of important compounds are generally used as intermediates for the construction of various chemically and biologically significant molecules,as well as for the synthesis of drugs and natural products.However, sulfones as undesired side products are easily formed in the oxidation action.Therefore,how to control the oxidation process of sulfides to sulfoxides becomes a crucial problem.The research develops Br₂ or bromic substitute as a catalyst,NaNO₂ or t-BuONO as a cocatalyst for activation of oxygen to highly selective aerobic sulfide oxidation.The system of Br₂/NaNO₂/O₂ is oxidated sulfides to sulfoxides under room temperature and pressure.It could make the conversion to 100%by using 0.015 mL(3x)of Br₂,0.0345g (5x)of NaNO₂ for 1h.,and the yield of methyl phenyl sulfide is up to 96%.HBr/t-BuONO/O₂ catalytic system is not only reacted at room temperature and pressure but also used HBr as the substitute of Br₂ to make safe in the operation.It could make the conversion to 100%by using 0.03 mL(40%,3x)of HBr,0.04 mL(3x)of t-BuONO for 2 h., and the yield of methyl phenyl sulfide is up to 96%.This thesis designs DBDMH/NaNO₂/O₂ system.Methyl phenyl sulfide as a model compound is converted to the corresponding sulfoxide under pressure.In the optimal reaction conditions:0.0572g(2x)of DBDMH,0.0345g(5x)of NaNO₂,1MPa of oxygen under 100℃for 3 h,the yield of methyl phenyl sulfide is up to 95%.It could make the conversion to 100%by using 0.0572g(2x)of DBDMH,0.05 mL(4x) of t-BuONO,0.8 MPa of oxygen under 50℃for 2h.,and the yield of methyl phenyl sulfide is up to 96%.the reaction conditions are milder than the system of DBDMH/NaNO₂/O₂, because t-BuONO develops a more efficient NO source than NaNO₂.The oxidation of a broad range of sulfides have been studied in the four transition-metal-free catalytic systems above,and their structures were characterized by IR,¹H NMR,¹³C NMR and MS.It shows the sulfides are converted to sulfoxides without the formation of sulfoxides as an undesirable decomposition and the yields of sulfoxides are high, and yields of derivatives with electron-donating groups were higher than that with electron-withdrawing groups.The possible mechanism is inducted.