Analysis of Reaction Mixtures in the Oxidation of Cyclohexane

To fully analyze the reaction mixtures from cyclohexane oxidation,a united analyzing method was established based on the comparison of feasibility of all kinds of analysis methods,including analyzing adipic acid,glutaric acid,and succinic acid (abbreviation “three acids”) by HPLC technique,analyzing cyclohexane,cyclohexanol,and cyclohexanone by GC technique,and analyzing the peroxide and ester by chemical titration.In order to make an accurate analysis of the “three acids”in the reaction mixtures by HPLC,the effects of several factors such as UV wavelength,mobile phase composition and its pH value,and mobile phase flow rate,on the retention time and separation efficiency of the “three acids”were investigated. It was found that the optimal conditions for the separation of the “three acids”were:the UV wavelength was 212 nm,the composition of flow phase was potassium dihydrogen phosphate-methanol buffered solution with 15%-30% methanol and its pH=3-4,and the flow phase velocity was 0.8 mL/min.In addition,the precision and accuracy of the above three analytical methods were analyzed,and the results showed that the relative standard deviations of the three analysis methods were less than 0.71%,confirming that the chemical analysis method was reliable.