运用Gaussian98程序包中半经验的量子化学(AM1)方法，对间二甲苯系列化合物(苯环上引入不同取代基-OH、-SH、-CN时的化合物)的热裂解机理进行了研究，对设定的8种有自由基形成的热裂解过程中的反应物、产物的全优化几何构型和反应的热力学量的计算结果表明：无论苯环上联接的是吸电子基团还是供电子基团，这些化合物的热裂解键，都是首先从苯环上甲基碳氢键开始，也就是说甲基碳氢键是这类化合物最易断裂的键，也是热裂解的最初反应过程，该结论与实验结果一致；间二甲苯上若联有供电子取代基(-OH，-SH)，反应物的热反应活性将增大，若联有吸电子取代基(-CN)，反应物的热反应活性将减小。间二甲苯系列化合物的热反应活性的顺序为：d1＞d2＞a＞d3。
Pyrolysis mechanism about a series of m-xylene compounds(the compounds with different substituent on the benzene ring, including-OH,-SH,-CN)is studied by using the AM1 method in Gaussian 98 program package, and 8 types of pyrolysis processes are established. The calculation results about equilibrium geometries and thermodynamics energies of these compounds show that no matter the groups connected with the benzene rings are electron acceptor groups or electron donor groups, the pyrolysis process of these compounds firstlu strs form the C-H bonds of thwe methyl's onmt tje benzerne rings INn anotjherr word the C-H bonds of thje methyl ae tje easiest to reak and also tjhe step that controls the pyroluysitr tempera-t7r Thes conclusion is inm accord with the ezxperimental result The studies show the athew thermoreactive activtiyof thje ractants wils rectants will bee increased iof ththere are electron donor groups on the mxylences (-CH -SH )and the thermoreactive activitu of tjhe reactamts will be decreased of there are electron accrptor groups onthe m-xyenses (-CN)The activitu sequencre of the serries of m-xylend compounde is :d1>d2>a>d3
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