Study On The Regularity Of C-C Cleavage In Oxidation Of Cycloalkanes?C₅-C₈? With Oxygen Catalyzed By Metalloporphyrin

Cycloalkanes are an important class of petrochemicals that can be used to prepare a variety of chemical raw materials through catalytic oxidation.Such as cycloalkanol,cycloalkanone,cycloalkyl hydroperoxide and aliphatic diacids,these are used widely.Among them,cycloalkanols and cycloalkanones are important raw materials for the preparation of polyamide polymer and other chemical products,cycloalkyl hydroperoxides can be decomposed into cycloalkanols and cycloalkanones,and aliphatic diacid is a direct raw material for the synthesis of polyamide polymer.Therefore,catalytic oxidation of cycloalkanes has become one of the popular research areas in the chemical industry,and has been the research interest of the majority of chemical science and technology workers.At present,the catalytic oxidation of cycloalkanes in the industry is mainly carried out by using Co²⁺as a catalyst and O₂ as an oxidant at 150 ? to 170 ?,there are problems such as high reaction temperature,poor selectivity of target products,unclear reaction rules,and unclear reaction mechanism in this method,in particular,the source of the aliphatic diacid is not clear,which makes it impossible to effectively control the formation of the aliphatic diacid,which directly leads to poor selectivity of the product in the reaction process.Therefore,the systematic study on the catalytic oxidation of C-C in cycloalkanes and the effective regulation of the formation of aliphatic diacids in cycloalkanes products have important theoretical and practical applications for the catalytic oxidation of cycloalkanes.In this paper,O₂ was used as oxidant,5,10,15,20-tetrakis?p-chlorophenyl?porphyrin cobalt?II??T?p-Cl?PPCo?as catalyst.the order and distribution of oxidation products of cycloalkanes?C₅-C₈? were studied systematically without solvent,especially the oxidative cleavage of C-C in the catalytic oxidation of cycloalkane?C₅-C₈?.Based on the oxidative cleavage of cycloalkane?C₅-C₈? C-C that is determination of the formation process of aliphatic diacid,the process of oxidizing cycloalkane?C₅-C₈? catalyzed by metalloporphyrin and the regulation of aliphatic diacid formation was proposed.The effective inhibition of aliphatic diacids is achieved,and the selectivity of oxidation products?cycloalkanols and cycloalkanones?is improved.The primary content of this dissertation could be summarized as follows:1.Using p-chlorobenzaldehyde and pyrrole as materials,5,10,15,20-tetrakis?p-chlorophenyl?porphyrin was synthesized by Lindsey method,Propionic acid method,Mixed acid method and Grinding method respectively.And studies have shown that the yield of synthetic porphyrin by grinding is higher,the molar ratio of p-chlorobenzaldehyde and pyrrole is 1:1,grinding at room temperature for 20 min,5,10,15,20-tetrakis?p-chlorophenyl?porphyrin yield reached 12.5%.Using DMF as a solvent,the molar ratio of 5,10,15,20-tetrakis?p-chlorophenyl?porphyrin to anhydrous cobalt acetate is 1:10,reflux for 24.0 h to synthesis 5,10,15,20-tetrakis?p-chlorophenyl?porphyrin cobalt?II??T?p-Cl?PPCo?,yield reached 85.8%.Using ethylenediamine,cyclohexanediamine and 5-chlorosalicylaldehyde as materials,and anhydrous ethanol was as solvent,the reaction was carried out for 4.0 h at room temperature to synthesis Salen I and Salen II,and the yields were 73.2%and 67.4%,respectively.Using Salen I,Salen II and anhydrous cobalt acetate,anhydrous copper acetate,zinc acetate dihydrate as the material respectively,anhydrous ethanol as solvent,reflux for 8.0 h,to synthesis Salen I-Co,Salen I-Cu,Salen I-Zn,Salen II-Co,Salen II-Cu,Salen II-Zn,their yields were 54.3%,60.3%,64.3%,48.3%,55.7%,and58.3%,respectively.2.Using 5,10,15,20-tetrakis?p-chlorophenyl?porphyrin cobalt?II?as catalyst and O₂ as oxidant,the order and distribution of catalytic oxidation products of cycloalkane?C₅-C₈?were studied systematically.And studies have shown that catalytic oxidation of cyclopentane and cyclohexane first produces cycloalkanols,cycloalkanones and cycloalkyl peroxides at temperatures which auto-oxidation does not occur?110?¹20??,with reaction time prolonged,the formation of aliphatic diacids was detected.The formation of adipic acid was started under the condition that the cyclohexane was reacted at 110? for 4.0 h.Under this condition,the conversion of cyclohexane was 0.89%,and the yield of adipic acid was 0.07%.The formation of glutaric acid was started when cyclopentane was reacted at 100? for1.5 h.Under this condition,the conversion of cyclopentane was 0.37%,and the yield of glutaric acid was 0.02%.The production of aliphatic diacids was not detected at cyclopentane and cyclooctane at temperatures which auto-oxidation does not occur?100?,95¹05??.The interconversion of oxidation products in the catalytic oxidation of cyclopentane and cyclohexane was systematically studied,studies have shown that the formation of aliphatic diacids is mainly derived from the oxidation of cycloalkanones,and cyclopentanol and cyclohexanol can be oxidized to form corresponding ketones cannot be directly oxidized to form aliphatic diacids.It is indicated that the oxidative cleavage of C-C in the catalytic oxidation of cycloalkane?C₅-C₈?mainly occurs in the catalytic oxidation of cycloalkanone,the ability of different cycloalkane C-C to catalyze oxidative cleavage is different.3.Using 5,10,15,20-tetrakis?p-chlorophenyl?porphyrin cobalt?II?as catalyst and O₂ as oxidant,further research was carried out by means of reaction kinetics study,reaction intermediate state capture and quantum chemical calculation,the regularity of C-C cleavage of oxidation in cycloalkanes?C₅-C₈?was further studied.Studies have shown that the catalyst T?p-Cl?PPCo can significantly reduce the apparent activation energy of the oxidation reaction,such as E_catalysis?111.0 kJ/mol?<E_{auto-oxidation}?271.8kJ/mol?for cyclohexane,E_catalysis?71.2 kJ/mol?)<E_{auto-oxidation}?126.6 kJ/mol?for cyclohexanone,E_catalysis?78.4 kJ/mol?<E_{auto-oxidation}?152.1 kJ/mol?for cyclopentane,E_catalysis?66.8kJ/mol?<E_{auto-oxidation}?157.1 kJ/mol?for cyclopentanone.The apparent activation energy of the cycloalkanone catalytic oxidation is less than the apparent activation energy of the catalytic oxidation of the corresponding cycloalkane,such as Ecyclohexanone?71.2kJ/mol?<Ecyclohexane?111.0kJ/mol?,Ecyclopentanone?66.8kJ/mol?<E_cyclopentane?78.4 kJ/mol?.Catalytic oxidation of the cycloalkanone to form an aliphatic diacid that is the C-C cleavage process,firstly cleavage the cyclohexane ketone?C-H,the activation energy of the?C-H reaction is different,resulting in different cycloalkane catalysis different ability to oxidize to form aliphatic diacids.This process has also been verified at the level of quantum chemical calculations.The study further confirmed that the oxidative cleavage of the C-C in the catalytic oxidation of cycloalkane?C₅-C₈?mainly due to the deep oxidation of cycloalkanone.4.The decomposition of cycloalkyl peroxide in the catalytic oxidation of cycloalkane by Salen-Zn catalyzed decomposition of cycloalkyl peroxide to cycloalkanol,inhibits the formation of cycloalkyl ketone,and inhibits the formation of aliphatic diacids,a significant increase in the overall selectivity of the cycloalkanol and cycloalkanone was achieved.Compared with 5,10,15,20-tetrakis?p-chlorophenyl?porphyrin cobalt?II??T?p-Cl?PPCo?alone as a catalyst,when 5-chloro-salicylaldehyde cyclohexanediamine Schiff base zinc?Salen II-Zn?and5,10,15,20-tetrakis?p-chlorophenyl?porphyrin cobalt?II??T?p-Cl?PPCo?in a molar ratio of 2:1,120?,1.4 MPa O₂ pressure for 8.0 h,adipic acid selectivity during cyclohexane catalytic oxidation from 16.86%to 1.12%,the conversion of cyclohexane was 4.18%.This regulation method also shows a good regulation effect on cyclopentane.