Study Of Selective Aerobic Oxidation Of Sulfides Based On Ionic Liquids

The selective oxidation of organic sulfides to sulfoxides is a challenging research interest in synthetic organic chemistry, because of the importance of sulfoxides as intermediates in organic synthesis and medical chemistry. In this paper, the first demonstration means of co-catalysis used tribromide ionic liquids (ILs-Br3) as main catalyst and nitrate ionic liquids or TBN as catalytic promoter was reported. The three catalytic systems were established.The established N-type tribromide ionic liquids/TBN/air systems. In this paper, A series of tribromide ionic liquids have been synthesized such as N-methyllimidazole-type tribromide ionic liquids, pyridine-type triromide ionic liquids, quaternary ammonium salt type tribromide ionic liquids and geminal dicationic ionic liquids. And a new characterization method was proposed. The system of N-type tribromide ionic liquids/TBN/air systems was established. The thioanisole was used as a model substrate in the catalytic oxidation systems, and all catalytic systems can achieve the oxidation of sulfides. The conversion rate of thioanisole reaches 99% and the selectivity reaches 100%. In this reaction, we have achieved the 12 different kinds of sulfides oxidation.The established P-type tribromide ionic liquids/TBN/air systems. In this paper, the synthetic methods of tribromide ionic liquids have been improved, and the "indirect method to generate Br2" was used to synthesis of P-type tribromide ionic liquids. In these catalytic oxidation systems, P-type tribromide ionic liquids were used as a source of bromine, TBN as nitrogen source, and air as the oxidant. An innovative method was discovered to solve the separation tribromide ionic liquids with sulfoxides. This method is more suitable for the mixture of TBPBr3 and sulfoxides, and the recovery of TBPBr3 from sulfoxides was over 90%. The TBPBr3 could be reused for three times without significant loss of activity. Under normal temperature and pressure, and the sulfoxidation was realized within 2-3 h for the conversion rate than more 99%,100% selectivity.The established tribromide ionic liquids/nitrate ionic liquids/air systems. It is the first time for the synthesis of nitric acid ionic liquid by strong base anion exchange resin. In this system, nitrate ionic liquids were used to instead of TBN as catalyst. Six different pure ionic liquids systems were established. A variety of sulfide oxidation was achieved. All systems normal temperature and pressure to achieve a period of 3.5 hours for model compound thioanisole conversion was greater than 99%, selectivity of 100%. The recycling of TBPBr3/TBPNO3 catalyst system was achieved, catalytic system can be reused for three times without significant loss of activity. In this reaction, we have achieved the 12 different kinds of sulfides oxidation.In this paper, the selective oxidation of different functional groups, different spatial arrangement of the electronic structure of complex sulfide substrates were studied to clarify the catalytic oxidation system in the main catalyst and co-catalyst synergies between catalytic activity and reaction mechanisms and selection the key factors of control, revealing the reaction mechanism for the selective oxidation of sulfide sulfoxide. This provides theoretical guidance for the design of highly efficient selective catalytic aerobic oxidation of sulfide by new systems.