单双核金属配合物选择性催化氧化对甲氧基苦杏仁酸  

Selective Oxidation of 4-Methoxymandelic Acid Catalyzed by Mononucleonic and Binucleonic Metal Complexes

作　　者：于卫峰[1] 孟祥光[1] 刘莹[1] 李小红[1] 

机构地区：[1]四川大学化学学院绿色化学与技术教育部重点实验室,成都610064

出　　处：《物理化学学报》2013年第9期2041-2046,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(21073126,21273156)资助项目~~

摘　　要：制备了以铜、钴、锰为中心离子的三种单核金属配合物L^1Cu、L^1Co、L^1Mn(L^1=N,N'-(2-羟乙基)丙二酰胺)和三种双核金属配合物L^2Cu、L^2Co、L^2Mn(L^2=N,N'-{2-(2-羟乙基氨基)乙基}丙二酰胺).研究发现在缓冲溶液中六种金属配合物能将对甲氧基苦杏仁酸(4-MMA)高选择性地氧化成对甲氧基苯甲醛(AAD)以及少量对甲氧基苯甲酸(4-MBA),AAD的选择性(S)大于96%.然而不同的催化体系在反应速率上表现了很大的不同:铜金属配合物的催化活性最好;双核配合物表现出更高的催化效率.研究了酒石酸(TA)、磷酸(H_3PO_4)、醋酸(HAc)三种缓冲溶液体系对L^1Cu催化H_2O_2氧化4-MMA反应的影响,结果表明缓冲溶液种类对反应速率和选择性影响很大.研究了35°C时弱酸性条件(pH值从2.5到4.5的范围内)在酒石酸缓冲溶液中六种金属配合物催化H_2O_2氧化4-MMA的动力学,计算出不同pH值条件下催化反应的表观反应速率常数k_(obs),并且讨论了pH值对催化反应的影响.Three kinds of mononucleonic metal complexes of L1Cu, L1Co, and L1Mn （L1=N,N＇-bis-（2-hydroxyethyl）-malondiamide）, and three kinds of binucleonic metal complexes of L2Cu, L2Co, and L2Mn （L2= N,N＇-bis{2-（2-hydroxyethylamino）ethyl}-malondiamide） were prepared. These complexes exhibited good catalytic performance for the selective oxidation of 4-methoxymandelic acid （4-MMA） by H2O2 in buffer solution, with 〉96% selectivity to anisaldehyde （AAD） and a small percentage to 4-methoxybenzoic acid （4-MBA）. However, the reaction rates were quite different for these catalytic systems, in which the copper complex was the best candidate as the catalyst for the oxidation of 4-MMA. The binucleonic complexes displayed obviously better catalytic performance than the mononucleonic complexes. The effect of the applied buffers （tartaric acid （TA）, H3O4, HAc） on the catalytic performance in terms of activities and selectivities for the oxidation of 4-MMA by H2O2 were investigated. The reaction kinetics of 4-MMA oxidation catalyzed by six complexes was studied in detail. The apparent first-order rate constants （kobs） were obtained in the pH range of 2.5 to 4.5. The pHeffect on the catalytic oxidation was discussed in this paper.

关 键 词：对甲氧基苦杏仁酸 金属配合物 选择性氧化 脱羧 木质素 

分 类 号：O643.32[理学—物理化学]