Efficient and selective hydrogen peroxide-mediated oxidation of sulfides in batch and segmented and continuous flow using a peroxometalate-based polymer immobilised ionic liquid phase catalyst

Abstract

ARTICLE This journal isThe peroxometalate-based polymer immobilized ionic liquid phase catalyst [PO 4 {WO(O 2 ) 2 } 4 ]@PIILP has been prepared by an anion exchange of ring opening metathesisderived pyrrolidinium-decorated norbornene/cyclooctene copolymer and shown to be a remarkably efficient system for the selective oxidation of sulfides under mild conditions. A cartridge packed with a mixture of [PO 4 {WO(O 2 ) 2 } 4 ]@PIILP and silica operated as a segmented or continuous flow process and gave good conversions and high selectivity for either sulfoxide (92% in methanol at 96% conversion for a residence time of 4 min) or sulfone (96% in acetonitrile at 96% conversion for a residence time of 15 min). The immobilized catalyst remained active for 8 h under continuous flow operation with a stable activity/selectivity profile that allowed 6.5 g of reactant to be processed (TON = 46,428) while a single catalyst cartridge could be used for the consecutive oxidation of multiple substrates giving activity-selectivity profiles that matched those obtained with fresh catalyst . IntroductionThe selective oxidation of sulfides is a challenging and technologically important process as sulfoxides and sulfones are versatile intermediates used in the synthesis of fine chemicals, bioactive compounds, agrochemicals, 1 as chiral auxiliaries 2 and most recently as ligands for transition metal asymmetric catalysis. 3 Moreover, sulfide oxidation is also the basis for the catalytic oxidative desulfurisation of crude oil in which sulfur compounds are removed by selective extraction of their sulfones into a polar solvent under much milder conditions than typically required for classical industrial catalytic hydrodesulfurization. 4 Sulfoxidations have traditionally employed either strong oxidants, (e.g. nitric acid or KMnO 4 ) which suffer numerous drawbacks such as low yields, extreme reaction conditions and poor E-factors, 5 or reagents such as mchloroperbenzoic acid, 6 UHP, 7 NaClO, 8 NaIO 4 , 9 oxone 10 and dimethyldioxirane 11 which are expensive, must be used in excess, generate stoichiometric amounts of by-product and involve protocols that require long reaction times, high temperatures and complicated handling procedures. Since hydrogen peroxide is economical, more environmentally benign and relatively atom efficient it is considered the oxidant of choice and as such numerous organocatalysts, 12 enzymes 13 as well as transition metal catalysts based on iron, 14 manganese, 15 vanadium, 16 titanium, 17 ruthenium, 18 molybdenum, 19 tungsten, 20 and zinc 21 have been developed for this process. In this regard, an efficient catalyst must be highly selective for either sulfone or sulfoxide, inexpensive, easy to prepare and handle, operate under mild conditions across a wide range of substrates and functionality, have long term stability and be easy to recover and recycle. While several of these criteria have been successfully realized there is still a demand to identify and develop alternative systems to address remaining drawbacks ...

A Concise Review on Synthesis of Sulfoxides and Sulfones with Special Reference to Oxidation of Sulfides

“…Besides these, H2O2 in combination with variety of catalysts have been most frequently used in the oxidative synthesis of sulfones. For instance, combination of Merrifield resin supported peroxomolybdenum (VI) compounds-H2O2 [136], PDDA-SiV2W10-H2O2 [137], polypyridiniumphosphorotungstate-H2O2 [138], MnSO4-H2O2 [139], trifluoroacetophenone-H2O2 [140], peroxometalate based polymer immobilised ionic liquid-H2O2 [141], polymer-immobilized peroxotungsten compound-H2O2 [142], silica bromide-H2O2 [143], TaC / NbC-H2O2 [144], cyanuric chloride-H2O2 [145], borax-H2O2 [146], silicasulfuric acid-H2O2 [147], TiO2 -H2O2 [148], sulfamic acid-H2O2 [149], and H2O2 in supercritical carbon dioxidewater [150], are few of the noteworthy and recently reported catalystoxidant combinations to effect oxidation of sulfides to sulfones. In addition to these, Jereb et al [151] reported a catalyst-free, solvent-free and functional group compatible protocol for the oxidation of sulfides to sulfones using 30 % H2O2 as the oxidant.…”

New perspective to Keplerate polyoxomolybdates: Green oxidation of sulfides with hydrogen peroxide in water

“…Recently, various efficient systems for oxidation of organic compounds with different oxygen sources such as O 2 and H 2 O 2 in the presence of POM catalysts have been developed [15][16][17]. For example peroxophosphotungstate-based pyrrolidinium-decorated polymer immobilized ionic liquid [PO 4 {WO(O 2 ) 2 } 4 ]@PIILP has been used for the oxidation of sulfides under mild conditions using hydrogen peroxide as oxidant [18]. In the other works, SiW 11 MC (M = Mn, Fe, Cu, and Co) was used for selective oxidation of sulfides to sulfoxides or sulfone using H 2 O 2 35% as a clean oxidant [19].…”

Hydrogen peroxide-mediated synthesis of 2,4-substituted quinazolines via one-pot three-component reactions under metal-free conditions

“…Doherty et al successfully replaced strong oxidants by hydrogen peroxide for sulfoxidation reactions. 19 Devi et al previously employed hydrogen peroxide instead of organic peroxides for the synthesis of N-(pyridin-2-yl)benzamides. 20 Zhou et al described hydrogen peroxide-mediated transformations of enamides to generate substituted a-acyloxyketones.…”