Synthesis Of Metallo-dueteroporphyrin Derivatives And The Study Of Their Biomimetic Catalytic Activities

The selective oxidation of hydrocarbon is one of the most important reactions in the chemical engneering. Finding the catalysts for the activation of C-H bond is the pivotal issue in the development of chemistry. Metalloporphyrins, as one kind of biomimetic catalysts for cytochrome P-450, are the potential catalysts for the oxidation of hydrocarbon and have been attracting much attention from organic and industrial chemists. However, several drawbacks exist. On the one hand, preparations of these porphyrins, especially the substituted ligands are very expensive; on the other hand, the catalytic activity and selectivity of these catalytic reactions still need to be improved. Deuteroporphyrin dimethylester and its metallo complexes can be prepared in high yield from the red blood pigment heme which is available in almost any desired amount from slaughterhouse wastes. The high accessibility of deuteroporphyrin dimethylester together with its excellent stability and the close relationship to the naturally hemes makes it an ideal compound to mimic enzymatic systems based on heme. Investigation of the biomimetic catalytic activities of the metallodeuteroporphyrin derivatives should be helpful to developing and designing the new and effective catalysts for oxidation.In this thesis, firstly, we synthesized the compound deuteroporphyrin dimethyl ester from chloro hemin, then the compounds 17～21 were prepared by introducing different substituents into the 3-/8-sites of deuteroporphyrin and the compounds 11～16 and 22～24 were synthesized by introducing different substituents into the 13-/17- sites of deuteroporphyrin. Secondly, we synthesized the compound 26 and 28, which contain dithiol bond and two active centres. Thirdly, we have supported deuteroporphyrin on the PEG1500 by covalent bond. Then, these synthesized ligands were complexed with metallo ions and their catalytic activities and selectivities in the oxidation of hydrocarbon with air were studied in detail.The metallodeuteroporphyrins [metal=ClFe(Ⅲ), Co(Ⅱ) and ClMn(Ⅲ)], have been used as the catalysts in the oxidation of cyclohexane,p-xylene and cyclohexene with air as the oxidant. According to the results of our experiments, metallodeuteroporphyrins can smoothly catalyze the oxidation of these substrates under the selected conditions. For example, in the oxidation of cyclohexane catalyzed by Co(Ⅱ) (DPDME), the conversion and the total selectivity of cyclohexanol and cyclohenone have reached 18.6% and 84.6%, respectively. The turnover number of the catalysts is 85147, markedly higher than that of the simple metallo-porphyrins. These results may be attributed to their different mechanism in forming the active medium.The metallodeuteroporphyrins derivatives with different substituents in 3-/8-sites have been used as the catalysts in the oxidation of cyclohexane with air. The results indicate that withdrawing-electron substituents can improve the catalytic activities of metallodeuteroporphyrins. Co(Ⅱ) [DP(β-Br)2DME] shows the highest activity. The conversion of cyclohexane has reached 23.57% and the total yield of cyclohexanol and cyclohexnone is more than 20%. The reason is that the withdrawing-electron substituents can increase the redox potential of the complex and improve the catalytic activities of these metallodeuteroporphrin derivatives.The metallodeuteroporphyrin derivatives with different substituents in 13-/17-sites have been used as the catalysts in the oxidation of cyclohexane with air. The results indicated that both the size and electronic properties of substituents influence the catalytic activity of metallodeuteroporphyrin derivatives. The activity decreased with the increasing of the size of goups. When Co(Ⅱ) (DPDOE) was used as the catalysts, the conversion of cyclohexane decreased to 15.0% with the reaction time 4.5 h, and the turnover number was also markedly lower than that of Co(Ⅱ) (DPDME). These results may be attributed to the fact that the big substituents hamper the formation of the mediumμ-oxo metallocomplexes.The catalytic activities of the metallodeuteroporphyrins containing dithiol bond have also been studied in the oxidation of cyclohexane with air. The results show that the catalytic activity has been evidently improved. Taking the Co(Ⅱ) (TPMP) as the example, the conversion of cyclohexane and the total selectivity of cyclohexanol and cyclohexnone have reached 27.4% and 92.0%, respectively. The phenomenone should be attributed to the dithiol bond in the molecular structure. On the one hand, the thiol can complexe to central metallo ion and facilated the formation of active medium; on the other hand, the redox property of dithiol can help the dehydrogenation of cyclohexanylperoxide and increase the yield of products.Finally, the catalytic activity of PEG1500-supported deuteroporphyrin has been studied in the oxidation of cyclohexane with air. The results shows that the time when the yield reached the highst is prolonged by 1.0～1.5h. Although the catalytic activity decreases, the total selectivity of cyclohexanol and cyclohexanone increases in a certain extent and the catalysts can be recycled twice.