2-(4-甲氧羰基苯基)-5-氨基-6-羟基苯并噁唑的热分解机理及动力学

Mechanism and Kinetics of Thermal Decomposition for 2-(4-methoxycarbonylphenyl)-5-amino-6-hydroxybenzoxazole

采用热重法(TG)测定了2-a(4-甲氧羰基苯基)-5-氨基-6-羟基苯并噁唑(MAB)的热分解过程,测定了MAB及其在热分解过程中不同阶段产物的红外光谱,运用量子化学GAMESS软件计算了MAB分子的键级,推断了MAB的热分解机理,结果表明MAB的热分解过程是一个五阶段过程,起始步骤是甲基酯的分解.根据不同升温速率下的热重曲线计算得到MAB第一阶段热分解反应的表观活化能Ea=157.1 kJ.mol-1和指前因子A=3.715×1013.

The thermal decomposition of 2-（4-methoxycarbonylphenyl）-5-amino-6-hydroxybenzoxazole（MAB）is mensurated by thermogravimetry（TG）, the IR spectra of MAB and its intermediates in thermal decomposition at various temperatures are determined, the molecular bond orders are calculated by GAMESS method of quantum chemistry, and also discussed is the mechanism of the thermal decomposition of MAB. All the results indicate that the thermal decomposition of MAB is a five-stage process. The O- C bond breakdown and the methoxy group disintegration occurr in the initial step of the decomposition and the parameters of thermal decomposition kinetics for MAB, such as activation energy （ Eα=157.1kJ·mol^-1） and pre-exponential factor（ A：3.715×10^13） are obtained by thermogravimetry.