Study On The Regularity For Oxidation Of C-H Bonds In Cycloalkanes（C₅-C₈） With O₂ Catalyzed By Metalloporphyrins

Cycloalkanes are a class of hydrocarbons found in petrochemicals.Its oxidation products such as cycloalkanols,cycloalkanones,cycloalkyl hydroperoxides and aliphatic chain diacids are widely used in foods,dyes,agriculture,lubricants,surfactants and other fields.At present,the above-mentioned oxidation products are obtained mainly by catalytic oxidation of cycloalkanes.For example,cobalt salt as a catalyst and oxygen as an oxidant,and catalytic oxidation at 150-170℃ and 1.0-2.0 MPa oxygen pressure.The main problems in this process are high reaction temperature,low substrate conversion rate,poor target product selectivity,unclear reaction mechanism,and unclear oxidation law.Especially the formation process and mutual conversion of cycloalkanol and cycloalkanone are not clear enough.The oxidation of cycloalkane C-H bonds is not clear enough.In this thesis,the intermediate product of oxygen-catalyzed oxidation of cycloalkanes is cycloalkyl hydroperoxide,which is widely accepted by scholars.By regulating the structure of metalloporphyrins,introducing bimetallic central metalloporphyrin catalysts,quantum chemical calculation and reaction kinetics study systematically explored the process and regularity of the conversion of cycloalkyl hydroperoxide to cycloalkanol and cycloalkanone,and obtained the regulation of oxidation of cycloalkane(C5-Cs)C-H bond.The main research contents of this dissertation are as follows.1.The structure of metalloporphyrins on the conversion of cycloalkyl hydroperoxides during the oxidation of cycloalkanes over 5,10,15,20-tetra(monochlorophenyl)porphyrin cobalt(Ⅱ)/manganese(Ⅱ),5,10,15,20-tetrakis(dichlorophenyl)porphyrin cob alt(Ⅱ)/mangane se(Ⅱ)and 5,10,15,20-tetrakis(trichlorophenyl)porphyrin cob alt(Ⅱ)/mangane se(Ⅱ)was investigated systematically.It was found that the catalytic activity of metalloporphyrins can be regulated by regulating the electronic effect of metalloporphyrin-substituted groups,but the distribution of cycloalkanols and cycloalkanones does not change with the increase of catalytic activity of the catalysts.As the number of Cl atoms on the metalloporphyrin substituent group increases,the conversion of cycloalkanes increases,and the ratio of cycloalkanols to cycloalkanones remains substantially unchanged.For example,with T(p-Cl)PPCo and T(2,3,6-tri Cl)PPCo as catalysts,the conversion rates of cyclopentane,cyclohexane,cycloheptane and cyclooctane rose from 1.51%,3.57%,5.31%and 24.71%to 2.16%,4.78%,6.15%and 39.87%respectively,while the selectivity of cycloalkanols was 13.71%and 7.31%,45.48%and 34.56%,12.07%and 6.75%,0.00%and 0.00%,the selectivity of cycloalkanones was 37.81%and 38.78%,40.59%and 51.68%,32.62%and 34.37%,44.27%and 45.17%respectively.2.A systematic study on the the regulation of cycloalkyl peroxide catalytic conversion about the oxidation of cycloalkanes by 5,10,15,20-tetrakis(p-chlorophenyl)porphyrin zinc and 5,10,15,20-tetrakis(p-chlorophenyl)porphyrin copper to 5,10,15,20-tetrakis(o-/m-/p-chlorophenyl)porphyrin cobalt(Ⅱ)/iron(Ⅱ)/manganese(Ⅱ)catalyzed oxygen.It was found that the introduction of the bimetallic central metalloporphyrin catalyst system can not only improve the conversion of cycloalkanes,but also significantly regulate the distribution of cycloalkanols and cycloalkanones.For example,when T(o-Cl)PPCo catalyzes the oxidation of cycloalkanes by oxygen,the conversion of T(p-Cl)PPCu increases the conversion of cyclopentane and cyclohexane from 1.67%and 3.88%to 2.29%and 4.41%respectively,while the selectivity of cycloalkanols increased from 11.16%and 39.98%to 11.82%and 46.64%respectively;When T(p-Cl)PPCo catalyzes the oxidation of cycloalkanes by oxygen,the conversion of T(p-Cl)PPZn increases the conversion rates of cyclopentane and cyclohexane from 1.51%and 3.42%to 2.07%and 4.17%,respectively.Although the selectivity of the cycloalkanols is not significantly improved,the selectivity of the cycloalkanone is significantly reduced.The research data indicates to some extent that the metalloporphyrin catalyzes the catalytic conversion of cycloalkyl hydroperoxide to cycloalkanols during the oxidation of cycloalkanes by oxygen.3.The conversion process of cycloalkyl peroxide in the oxidation of cycloalkanes with oxygen catalyzed by metalloporphyrins was investigated systematically at the B3LYP/6-31G(d)level in the Gaussian software.It is found that the energy barrier of the fourth path is the lowest,that is,the process of intermolecular hydrogen extraction of cycloalkyl hydroperoxide and cycloalkane to form cycloalkanol.It is a possible transformation path at the quantum chemical calculation level,which is supported by kinetic studies.To some extent,the conversion path and regularity of the oxidation intermediate cycloalkyl hydroperoxide in the catalytic oxidation of cycloalkanes are clarified,that is,the oxidation of C-H bonds of cycloalkanes.