Study On Selective Air Oxidation Of Sulfides Catalyzed By Poly Ionic Liquids

Sulfoxide is an important intermediate in organic synthesis,which has been extensively utilized in pharmaceutical,agriculture and other fields.It can be obtained by selective oxidation of sulfides.In the existing oxidation system of sulfides,the system using molecular oxygen or air as oxidant is more in line with the requirements of green chemistry,and also a hot spot of current research.In this paper,Br₃^-ion was used as the bromine source and TBN or NO₃^-ion was used as the nitrogen source to construct a two-component poly ionic liquids catalytic system,and air was used as oxidant to realize the highly selective oxidation of various sulfides.Firstly,a new green catalytic oxidation system of pyridine-type polytribromide ionic liquid/TBN/air was constructed.Four kinds of pyridine-type polytribromide ionic liquids catalysts?Poly[EVPy]Br₃,Poly[BVPy]Br₃,Poly[HVPy]Br₃,Poly[DVPy]Br₃?were synthesized and fully characterized.The selective oxidation of methyl phenyl sulfide was systematically investigated under ambient temperature and pressure with air as oxidant.The experimental results showed that when the dosages of Poly[DVPy]Br₃,TBN,acetonitrile and water were 0.26g?⁰.5mmol?,0.5 mmol,20 mL and 0.5 mL respectively,the conversion of 10 mmol methyl phenyl sulfide was complete after 2.5 h,with the selectivity over 99%and the yield of methyl phenyl sulfoxide over 96%.And the applicability of Poly[DVPy]Br₃ catalyst to thioether substrates containing different functional groups was investigated and it showed high selective oxidation efficiency for 20 kinds of sulfides,with the yields of sulfoxides over 89%.Secondly,a new green catalytic oxidation system of imidazole-type polytribromide ionic liquids/TBN/air was established.Four kinds of pyridine-type polytribromide ionic liquids catalysts?Poly[VEIm]Br₃,Poly[VBIm]Br₃,Poly[VHIm]Br₃,Poly[VDIm]Br₃?were prepared and fully characterized.The selective oxidation of thioanisole was systematically investigated under ambient temperature and pressure with air as oxidant.The experimental results showed that 10 mmol thioanisole could be completely converted in 2.5 h when 0.18 g?⁰.5mmol?Poly[VEIm]Br₃,0.5 mmol TBN,20 mL acetonitrile and 0.5 mL water were added,with the selectivity over 99%and the yield over 96%.And the oxidation research for 30 kinds of sulfides using Poly[VDIm]Br₃ as catalyst was carried out,with the major yields of sulfoxides over 90%.Finally,a new green catalytic oxidation system of polytribromide ionic liquids/polynitrated ionic liquids/air was developed.Four kinds of poly nitrated ionic liquids?Poly[VEIm]NO₃,Poly[VBIm]NO₃,Poly[EVPy]NO₃,Poly[BVPy]NO₃?were successfully prepared by anion exchange resin method and fully characterized.With air as oxidant,the selective oxidation of thioanisole was catalyzed by a bicomponent poly ionic liquid catalyst with polytribromide ionic liquids as bromine source and polynitrated ionic liquids as nitrogen source under normal temperature and pressure.The thioether substrates applicability of Poly[VEIm]Br₃ and Poly[VEIm]NO₃ catalytic system was examined,and it exhibited excellent catalytic effect for 12 kinds of sulfides,with the yields of sulfoxides over 88%.