Environmentally friendly epoxidation of olefins under phase-transfer catalysis conditions with hydrogen peroxide
Environmentally friendly epoxidation of olefins under phase-transfer catalysis conditions with hydrogen peroxide
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DOI：
10.1016/j.jcat.2007.05.001
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发表时间：
2007-07
影响因子：
7.3
通讯作者：
Y. Mahha;L. Salles;J. Piquemal;E. Briot;A. Atlamsani;J. Brégeault
中科院分区：
文献类型：
--
作者：
Y. Mahha;L. Salles;J. Piquemal;E. Briot;A. Atlamsani;J. Brégeault
几种催化体系：WO3⋅H2O/ h2o2 - H2O - h30 +/Q+A−/H3PO4/H2SO4/溶剂(Q+A−= Arquad 2HT®，[CH3(n-C8H17)3N]+Cl−；(CH3 (n-C8H17) 3 n] +就是HSO4−[CH3 (n-C8H17) 3 n] + H2PO4−;溶剂：chcl3或甲苯)在室温下选择性高效地将烯烃转化为相应的环氧化物。使用环烯并使用Arquad 2HT®作为相转移剂，当反应介质中同时存在磷酸盐和硫酸盐阴离子时，与使用其中一种或另一种体系相比，存在协同作用。如前所述，即使在室温下，当使用WO3⋅H2O代替Na2WO4⋅2H2O时，钨（VI）源的活性也显著增加，这表明钨（VI）源的重要性。考察了相转移剂Q+A−对WO3⋅H2O/ h2o2 - H2O - h30 +/Q+A−/甲苯体系的影响。在Q+A−（Q+= [CH3(n-C8H17)3N]+和A−= Cl−、HSO4−和H2PO4−）条件下，[CH3(n-C8H17)3N]+H2PO4−在室温下对环烯的转化效果最好。31P核磁共振实验表明，[PO4{W2O2(μ-O2)2(O2)2}2]3−和[HPO4{W2O2(μ-O2)2(O2)2}]2−与H3PO4和H2PO4−的配合物在有机相中有转移，而只有[PO4{W2O2(μ-O2)2(O2)2}2]3−与H3PO4/HSO4−或H2PO4−/H2SO4的配合物能识别转移。此外，酸敏感环氧化物可以使用添加氢化碳酸钠或优选的氢化磷酸二钠生成的缓冲液制备，从而对相应的环氧化物具有高选择性。数据表明，即使为获得高转化率必须增加反应时间，用磷酸氢二钠也能得到最好的结果。WO3⋅H2O/ H2O2-H2O /[CH3(n-C8H17)3N]+H2PO4−/甲苯催化体系可连续重复使用5次，无活性损失。
Several catalysis systems, WO3⋅H2O/H2O2–H2O–H3O+/Q+A−/H3PO4/H2SO4/solvent (Q+A−= Arquad 2HT®, [CH3(n-C8H17)3N]+Cl−; [CH3(n-C8H17)3N]+HSO4−, [CH3(n-C8H17)3N]+H2PO4−; solvent: CHCl3or toluene) were used to selectively and efficiently convert olefins to their corresponding epoxides at room temperature. With cyclooctene and using Arquad 2HT® as the phase-transfer agent, there is a synergy when both phosphate and sulfate anions are present in the reaction medium compared with systems using either one or the other. The importance of the tungsten(VI) source is, as found previously, underlined by the strong activity increase when WO3⋅H2O is used instead of Na2WO4⋅2H2O, even at room temperature. The influence of the phase-transfer agent Q+A−has been evaluated for the system WO3⋅H2O/H2O2–H2O–H3O+/Q+A−/toluene. With Q+A−(Q+= [CH3(n-C8H17)3N]+and A−= Cl−, HSO4−, and H2PO4−), the best results for the conversion of cyclooctene at room temperature are obtained with [CH3(n-C8H17)3N]+H2PO4−.31P NMR experiments show the transfer in the organic phase of the [PO4{W2O2(μ-O2)2(O2)2}2]3−and [HPO4{W2O2(μ-O2)2(O2)2}]2−complexes with H3PO4and H2PO4−, whereas only [PO4{W2O2(μ-O2)2(O2)2}2]3−can be identified with the addition of H3PO4/HSO4−or H2PO4−/H2SO4. Moreover, acid-sensitive epoxides can be prepared using buffers generated by the addition of sodium hydrogenocarbonate or, preferably, disodium hydrogenophosphate, leading to high selectivities toward the corresponding epoxides. The data show that disodium hydrogenophosphate gives the best results even if the reaction time has to be increased to obtain high conversions. The WO3⋅H2O/H2O2–H2O/[CH3(n-C8H17)3N]+H2PO4−/toluene catalysis system can be reused in 5 consecutive runs with no loss in activity.