Synthesis Of Tetraaza "14" Annulenen₄ Copper (Ⅱ) Complexes And Their Application In Catalytic Oxidation Of Styrene

Cytochrome P-450 enzymes are ubiquitous in nature where they catalyze a vast array of oxidation reaction, but they are difficult to prepare. Many model systems based on transition metal complexes of porphyrins, phthalocyanines, and Schiff-bases that can mimic enzymes have been widely investigated. The traaza[14]annuleneN4 ligand, which is a conjugated macrocycle containing a four-nitrogen donor core, is more electron-donating than the porthyrin ligand and has similar ability to bind the metal atom above the donor plane. The nonplanarity of the traaza[14]annuleneN4 ligand also grants considerable solubility in common organic solvents without the need for derivation, a major drawback with porphyrin complexes. Another advantage is its relatively low cost compared with that of porphyrins. By adopting several synthetic methods,7 copper complexes with various structures have been synthesized. These copper complexes were characterized by means of the IR, UV-Vis, elemental analysis. Copper complexes were used as catalysts for the oxidation of styrene and their catalytic activities were investigated. The electrochemical data and the QSAR (quantitative relationship between structure and catalytic activity) of catalysts was established. The reasearch results are summarized as follows:1.6,8,15,17-Tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine and 7,16-Bis(benzoyl)-6,8,15,17-tetramethyldibenzo[b,i] [1,4,8,11]tetraazacyclotetradecine copper complexes were synthesizes according to the report. A series of tetraaza[14]-annelenN4 copper complex were synthesized and characterized. They are listed as follows:7,16-Bis(p-methoxybenzoyl)-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraazacycl-otetradecine copper complex7,16-Bis(p-methylbenzoyl)-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclot-etradecine copper complex7,16-Bis(p-chlorobenzoyl)-6,8,15,17-tetramethy ldibenzo[b,i][1,4,8,11]tetraazacyclot-etradecine copper complex7,16-Bis(p-trifluoromethylbenzoyl)-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraa-zacyclotetradecine copper complex7,16-Bis(p-nitrobenzoyl)-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetrazacyclotetr-adecine copper complex 2. The catalytic activities of 7,16-Bis(benzoyl)-6,8,15,17-tetramethyldibenzo[b,i]-[1,4,8,11]tetraazacyclotetradecine copper catalyst was investigated by using TBHP oxidation of styrene. The influence factors such as solvent, temperature, reaction time, and TBHP to styrene molar ratio were also studied in detail. Oxidation of styrene catalyzed by copper complexes with different substitute groups on the tetraaza[14]annuleneN4 ring were studied. The conversion of styrene catalyzed by copper complexes were found to decrease in the order of OCH3>NO2>Cl≈CF3> H> CH3. The selectivity of benzaldehyde was found to decrease in the order of NO2> CF3>Cl>H>CH3>OCH3.3. By using linear regression method, the regression of the catalytic activity or the selectivity versus half-wave potential was obtained. The relationship can be expressed mathematically as selectivity of benzaldehyde=96.744E1/2-3.691, with a correlation coefficient of 0.989. Study on the structure-reactivity relationship will be helpful in designing the more powerful debenzotetraa[14]annelene complexes.