Study On The Catalytic Oxidation Mechanism Of Cumene

The selective oxidation reaction of alkylbenzene is one of the important branches in organic oxidation reaction.Its oxidation products(alcohols,ketones,peroxides,etc.)have high added value,and can be widely used in chemical and chemical industry.For the research on the oxidation reaction of cumene,the reaction mechanism is rarely reported in detail.The question for how cumene,molecular oxygen and catalyst interact and promote the reaction process in the oxidation process remains to be solved.In this thesis,density functional theory(DFT)is used to theoretically study the oxidation reaction mechanism at the B3LYP/6311+G(d,p)calculation level.(1)The auto-oxidation reaction of cumene is calculated by calculation.The oxidation process follows the free radical chain reaction mechanism.When the product cumene hydroperoxide ROOH is produced,the activation energy of the reaction is 67.87 KJ/mol,and the reaction emits energy of 220.03 KJ/mol.In the process of producing dimethylbenzyl alcohol ROH,the activation energy is 42.16 KJ/mol,and the reaction heat is 379.84.KJ/mol.(2)The oxidation reaction mechanism of cumene when NaOH is used as a catalyst is calculated by calculation,and it is mainly derived from the attraction of OH--p-cumene to produce cumene radical R·,which leads to the radical chain growth reaction.For the main path,in the process of ROOH generation,the reaction energy barrier is 58.56 KJ/mol,which is 9.31 KJ/mol lower than the reaction energy barrier of auto-oxidation reaction.when ROH is generated,heat is exothermic 454.36 KJ/mol,and the reaction energy barrier is 58.94 KJ/mol.(3)The structure of the basic ionic liquid[Bmim]OH and the micromechanism of the oxidation reaction process of cumene were studied by calculation.It was found that the most stable structure of ionic liquid[Bmim]OH is a complex containing carbene and water.There are two possible paths for the oxidation of cumene catalyzed by[Bmim]OH:one is the self-transfer of H on cumene,and the activation energies of the products ROOH and ROH are 12.40 and 7.28 KJ/mol respectively.The other is the mutual exchange of H on cumene and C-H on the imidazole ring,and the activation energy of the products ROOH and ROH are 6.23 and 2.48 KJ/mol,respectively,which are 6.17 KJ/mol and 4.80 KJ/mol lower than the activation energy of the former.Therefore,The reaction is easier to proceed along path B.Compared with the auto-oxidation reaction of cumene and the catalysis by NaOH,the activation energy of the reaction during[Bmim]OH catalysis is reduced by about 50 KJ/mol,which significantly increases the reaction rate and accelerates the reaction,and is consistent with the experimental results.(4)The PCM model was used to investigate the influence of benzene,water,acetonitrile,ethanol,and dichloromethane on the reaction of cumene oxidation.The addition of solvent is conducive to the stability of the reactants and products,and the polar solvent is more beneficial to the oxidation of cumene.Compared with unsolvated,the total exothermic heat of the reaction increases by 8.24-46.53 KJ/mol,and the addition of water and ethanol reduces the reaction energy barrier of 0.92-8.54 KJ/mol.