西佛碱钴络合物催化氧化苯酚  

CATALYTIC OXIDATION OF PHENOL BY COBALT SCHIFF-BASE COMPLEXES

作　　者：杜文[1] 王桂霞[1] 奚祖威[1] 

机构地区：[1]中国科学院大连化学物理研究所

出　　处：《分子催化》1990年第4期306-313,共8页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金

摘　　要：研究了不同结构的西佛碱钴络合物对苯酚氧化的催化性能,又以N,N′-乙撑二(水扬叉亚胺)钴为催化剂,考察了催化剂及底物浓度、温度、压力等不同条件对苯酚催化氧化的影响。In this paper we studied the activation of molecular oxygen and the homogeneous catalytic oxidation of phenol. Copper and cobalt complexes were used as catalysts. Among the four selected copper complexes, only Cu(acac)2 and Cu(Salde)2 in pyridine solvent were active toward the oxidation of phenol, about 20-40% phenol was reacted at 60℃, but p-benzoquinone was not detected in the oxidation products. CH3COOC6H5 was identified by GC-MS to be present in Cu ( acac ) 2 catalytic oxidation product, it means phenoxyl radical was formed as an intermediate through hydrogen abstraction of phenol and phenoxyl radical could not be converted to p-benzoquinone under these conditions. The catalytic behavior of a series of cobalt Schiff-base complexes for oxidation of phenol has also been investigated. Superoxo complex -the active species in catalytic oxidation was formed by coordination of an oxygen molecule to the cobalt complex, so the catalytic activity of cobalt Schiff-base increased with the increase of electronic density around the cobalt atom in the complex in the following order: Co ( Salphen ) >Co ( MeOSalen ) >Co ( Salen ) In addition to the electronic density around the cobalt atom, the steric factor caused by the ligand also affected the coordination and activation of the dioxygen, so the catalytic activity of CoMeOSalphen for phenol oxidation was obviously lower than that of Co Salphen. Some interesting results about the influence of reaction conditions, such as solvent, Co (Salen) and substrate concentration, reaction temperature and oxygen partial pressure on the oxidation of phenol were obtained. Aprotic solvent such as N, N' -dimethylformamide and N-methyl-pyrrolidone was better than alcohol for the oxidation of phenol to produce p-benzoquinone. Higher conversion of phenol was obtained with higher concentration of Co ( Salen ) catalyst at 60-80℃. The selectivity of p-benzoquinone formation decreased markedly with the increase of substrate concentration. The correlation bet

关 键 词：西佛碱 钴络合物 催化氧化 苯酚 

分 类 号：O625.312[理学—有机化学]