芳烃侧链氧化反应绿色化研究

【作者】 孙靖；

【导师】 汤杰；

【作者基本信息】 华东师范大学 ， 有机化学， 2004， 硕士

【摘要】 本论文主要致力于以清洁氧化剂氧化芳烃侧链制备芳香酸和芳香酮的研究。全文主要由三部分组成：（1） 非酸性有机溶剂中、钴催化下的芳烃侧链分子氧液相氧化反应研究；（2） 离子液体中的芳烃侧链分子氧氧化反应的研究；（3） 以H₂O₂和NaClO为氧化剂的芳烃侧链氧化反应初探。 一、非酸性有机溶剂中、钴催化下的芳烃侧链分子氧液相氧化反应研究 通过加入引发剂，成功地实现了以非酸性有机试剂—卤代苯，替代传统的低级脂肪酸作溶剂的芳烃侧链氧化反应。分别以(Co（OAc）₂／NaBr／HOAc和Co(C₁₈H₃₅O₂)₂／NH₄Br)为催化剂体系，AIBN为引发剂，芳烃侧链可在常压下被分子氧深度氧化为相应的酸。考察了芳环上有不同取代基时，溶剂、助催化剂、引发剂等对反应的影响，并考察了体系氧化的选择性。氧化底物包括氰基甲苯（邻-，间-，对-）、对位取代甲苯（X=F、Cl、Br、I、NO₂、OCH₃）以及对位取代邻氟甲苯（X=F、Cl、Br）。其中对溴苯甲酸、对甲氧基苯甲酸、对氰基苯甲酸的分离收率高达92％、94％和96％。 二、中性离子液体中NHPI催化的芳烃侧链分子氧液相氧化反应研究 首次尝试了以中性离子液体[Hex-mim]⁺BF₄^-作反应介质，N-羟基邻苯二甲亚胺（NHPI）为催化剂，分子氧为氧化剂的芳烃侧链液相氧化反应。在该体系中，芳烃侧链可在常压下被分子氧深度氧化为相应的酸。甲苯的转化率可达40％，吸电子取代基和位阻效应使转化率降低；推电子基对反应有利。乙苯、正丙苯能以较高的转化率生成相应的芳香酮；异丙苯氧化生成降解产物苯乙酮和α-甲基苯乙烯。 反应结束后，只需补加少量流失的催化剂，即可实现离子液体-催化剂体系的循环使用。 三、以H₂O₂和NaClO为氧化剂的芳烃侧链氧化反应初探 以RuCl₃为催化剂，分别以H₂O₂和NaClO为氧化剂，尝试了离子液体中的芳烃侧链氧化反应。结果表明，H₂O₂为氧化剂时，氧化反应能够发生，但转化率较低（≤14％）；NaClO氧化的反应产物中只检测到少量的氯代化合物。更多还原

【Abstract】 This dissertation consists of three parts (1) oxidation of substituted toluenes to the corresponding benzoic acids in non-acid solvents (2) oxidation of alkylarenes with molecular oxygen hi ionic liquids (3) Oxidation of alkyl aromatic compounds using H2O2 or NaCIO as oxidant and Ruthenium(III) as catalyst in ionic liquid.1. Oxidation of substituted toluenes with molecular oxygen to corresponding substituted benzoic acids under normal pressure hi non-acid solvents was investigated. Satisfactory results for oxidation of halo-toluenes, methoxy-toluenes and cyano-toluenes were obtained using Co(C18h35O2)/NH4Br or Co(OAc)2/NaBr/HOAc as catalysts in the presence of a radical initiator. The influence of substituted groups on benzene, solvents, cocatalysts and initiator on the oxidation result was studied. The selectivity of the oxidation system was also studied. The oxidation of para- substituted toluenes gave good yields, such as 92%, 94% and 96% for p-bromotoluene, p-methoxytoluene and p-cyanotoluene respectively. Radical initiator is the key species in the reaction.2. Oxidation of alkylarenes with molecular oxygen was investigated in neutral ionic liquid [Hex-mim]+BF4- for the first time. Using N-hydroxyphthalimide (NHPI) as catalysts, alkylarenes could be oxidized to the corresponding aromatic acids (or aromatic ketones) under normal pressure. Electron-withdrawing groups and steric effect decreased the reactivities while electron-donating groups were favorable for the oxidation.3. Oxidation of alkyl aromatic compounds in ionic liquid was studied tentatively using Ruthenium( III) as catalyst with hydrogen Peroxide and NaCIO as oxidant, respectively. Only <14% of conversions were obtained when H2O2 as oxidant, and a little chloride compounds were detected while using NaCIO as oxidant.更多还原