Catalytic Oxidation Study Of4’-R-2,2’:6’,2"-Terpridine Transition-metal Complex To Olefins And Alcohols

The catalytic oxidations of organic compound by means of transition metal complex have fundamental meaning in organic synthesis, industrial catalysis and enzyme catalysis. Chemists have long time sought to more stable and more effective catalyst in order to obtain a high conversion rate and the specific selectivity of substrate. Most of the traditional tetradentate ligands of homogeneous catalysts are Schiff bases, Pthalocyanines and Porphyrins which have been reported largely. In recent years, more and more researchers have paid attention to tridentate-chelated complexes. Although2,2’:6’,2"-terpyridine complexes were widely applied in electric materials, light hydrolysis, asymmetric catalysis and other fields, little of such were reported on the area of catalytic oxidation. So the study of catalytic activities of2,2’:6’,2"-terpyridine transition-metal complex has urgent and important meaning.The catalytic properties of a series of4’-R-2,2’:6’,2"-terpridine transition-metal complex were studied in this paper. TBHP (tert-butyl-hydrogen peroxide) being used as oxygen source, catalytic oxidatons of alkenes and alcohols were performed. According to the results of gas chromatography analysis, the influence of the catalytic effect for different substitutions on4’-postion of terpyridine were discussed, and the unique catalytic properties of different transition-metal were also investigated.In the first part, the widely application in various fields in recent years of tridentate ligand, such as terpyridine, were summarized. A theoretical basis for the biomimetic catalysis of our research was then constructed. In the end, the idea of research was put forward that various terpyridines with different substituent in4’position combine with different metal ion to form transition metal complexes which oxidative catalytic activities would be investigated.The second, third and fourth part described the catalytic behavior of four4’-R-2,2’:6’,2"-terpyridine copper(II) complexes, five4’-R-2,2’:6’,2"-terpyridine cobalt(II) and five4’-R-2,2’:6’,2"-terpyridine manganese(II) complexes. These complexes were used as catalyst to oxidize cyclohexene, styrene, benzyl alcohol and cyclohexanol when TBHP or oxygen as oxygen source. It was found that complexes with electron-withdrawing groups (-C1and-NO2) showed good values in catalytic activity. If4’-Cl-2,2’:6’,2"-terpridine-Cu(II) was used as catalyst, and TBHP as oxygen source, the conversion rate of styrene was78%. For cyclohexene and cyclohexanol were91%and78%separately. If oxygen used as oxygen source, the conversion rate of benzyl alcohol was82%when TEMPO was used as co-catalyst, the conversion rate of styrene more than99%when isobutyraldehyde was used as reducing agent. If4’-Cl-2,2’:6’,2"-terpridine-Co(Ⅱ) was used as catalyst, and TBHP as oxygen source, the conversion rate of cyclohexene was98%, styrene94%. If4’-Cl-2,2’:6’,2"-terpridine-Mn(Ⅱ) was used as catalyst, and TBHP as oxygen source, the conversion rate of cyclohexene was90%, and that of styrene was94%.In the five part,4’-(2-furanyl)-2,2’:6’,2"-terpyridine-Cu(Ⅱ), Co(Ⅱ), Mn(Ⅱ) and Fe(Ⅲ) complexes were used as catalyst to oxidize cyclohexene, styrene and benzyl alcohol in turn. It was found that under the condition of TBHP and80℃, the largest value of conversion rate(selectivity) for cyclohexene was92%(66%) when Fe(Ⅲ)-terpyridine was used as catalyst, for styrene was95%(88%) when Mn(Ⅱ)-terpyridine was applied, for benzyl alcohol was42-78%(86-100%) when these catalysts being used.