AM1 thermodynamic research of the pyrolysis mechanism of toluene (I)

Based on the experiment, the pyrolysis mechanism of the carbon matrix precursor toluene used for carbon material was studied with semi-empirical method AM1 of Gaussian 98 package,the equilibrium geometry of the reactants and free radicals were optimized. The standard thermodynamic parameters in different temperatures range were calculated. The thermodynamic calculation results show: when the pyrolysis temperature of toluene is relatively low(below 1073K), C-H bonds of the methyl on the benzene ring is broken firstly, and the reaction path of producing phenylmethyl is the main one(path 1). With temperature increasing(being above 1073K), C-C bond between phenyl and methyl is easy broken, the reaction path that produces phenyl and methyl is a chief one(path 2). This mechanism is in accord with the experiment. When studying the pyrolysis carbonization mechanism and initial pyrolysis carbonization reaction process of low-molecularly organic compounds used quantum chemistry calculation theory, semi-empirical method AM1 is still an efficient method.