Synthesis And Characterization Of NHPI Analogs And Study On The Solvent Free Catalytic Oxidation Of Toluene

For a long time,most of the hydrocarbon aerobic oxidation catalytic systems are facing environmental pollution,equipment corrosion and other issues,and the application prospects in the actual industrial production process are not optimistic.In recent years,organic small molecules have been favored by many chemists because of their advantages of no pollution,mild conditions,and no metal residues.The most important of these is the oxidation reaction of NHPI(N-hydroxyphthalimide)-based catalyst.Herein,NHPI analogues containing long-chain esters and sodium sulfonate structures were synthesized by three steps of hydroxylation,sulfonation and esterification.The mid product prepared in three-step reaction were combined with infrared spectroscopy,mass spectrometry and nuclear magnetic analysis and determined their structures.In order to study the complex catalytic oxidation of NHPI analogues,a new type aromatic carboxylic acid cobalt complex was synthesized and characterized by infrared spectroscopy and single crystal diffraction.The NHPI analogues prepared in the three steps and the cobalt complex were separately applied to the solventless catalytic oxidation of toluene.The results showed that all three NHPI analogues and cobalt complexes have certain catalytic properties.The solubility of NHPI analogues in the substrate toluene has a great influence on the catalytic effect under solvent-free conditions.The reaction of final NHPI analogue alone to catalyze the oxidation of toluene by molecular oxygen was studied under solvent-free conditions.The optimum reaction conditions for the reaction were as follows: 10 g toluene,4.16 g catalyst(8% of the toluene molar mass),temperature 140 ?,oxygen pressure 1.0 MPa,and reaction time 3 h.Under these conditions,the conversion of the raw material toluene was 10.32%,and the total selectivity of the product benzaldehyde,alcohol,and acid was 83.17%.Through the comparison test of cobalt catalyst,it was found that the effect of the prepared cobalt complex on the oxidation of toluene was comparable to that of industrially common cobalt catalysts.The reaction of NHPI analogue/cobalt hydroxymethylbenzoate complex to catalyze the oxidation of toluene by molecular oxygen was studied under solvent-free conditions.The optimum reaction conditions for the reaction were as follows: toluene 10 g,NHPI analog/cobalt molar ratio of 1:0.2,catalyst 3% of the toluene molar mass,reaction temperature 160 ?,and oxygen pressure 1.2 MPa.The reaction time was 3 h.Under this condition,the conversion of the raw material toluene was 21.49%,and the total selectivity of the product benzaldehyde,alcohol,and acid was 94.43%.