Liquid Phase Oxidation Of P-chlorotoluene To P-chlorobenzaldehyde

The series oxygenous compounds such as alcohol,aldehyde,carboxylic acid, which is prepared by selective oxidation of substitutional toluene derivatives, are very important organic chemical intermediates,and are widely used, possessing high additional value.However,the selective oxidative products are always not thermostable compounds,for they are easily oxidized into carbon oxide,carbon dioxide and water.So,one of the challenging projects nowadays is how to protect the oxidative products from further oxidation.This dissertation focuses on the systematic study of liquid phase oxidation of p-chlorotoluene to p-chlorobenzaldehyde,including the component of the catalyst,the optimization of the catalytic conditions,and how the reaction temperature,reaction time,the oxygen flux and the amount of the solvent influence the reaction system.The Co-Mn-Br/γ-A₂O₃ solid phase catalyst made by the dipping method was applied to catalyze the oxidation of p-chlorotoluene to p-chlorobenzaldehyde to evaluate the catalytic activity.Moreover,XRD,SEM techniques were used to characterize the catalyst,and the optimal preparation conditions of the catalyst according to the characterization and the evaluation of the reaction results were found,and we also analyzed how the preparation conditions influence the catalytic activity as well.We found that the composition of the catalyst affects the catalytic activity very strongly,and the reaction conditions influence the conversion of the p-chlorotoluene and the selectivity of the formation of the p-chlorobenzaldehyde.First of all,when loading the active components onγ-A₂O₃,the activity and the conversion increased dramatically,secondly,the burning temperature of the catalyst can not be too high,otherwise,the catalyst will lose the activity,thirdly,the acetic acid as the solvent played an important role in the reaction system,when it is substituted by other solvents such as methanol,ethanol,actonitrile,the catalytic activity decreased dramatically.The optimal composition of the catalyst is Co..Mn:Br=8:2:5,and the optimal burning temperature is 500℃.The optimal reaction conditions are:reaction temperature- 110℃,reaction time- 6 h,oxygen flux- 30mL/min;the substrate (p-chlorotoluene)/the solvent(acetic acid)= 1/2.On the optimal conditions,the conversion of the p-chlorotoluene is 45.0%,the selectivity of the formation of p-chlorobenzaldehyde is 62.8%,and the yield of the formation of p-chlorobenzaldehyde is 28.3%.