丝氨酸热分解机理的研究  

Studies on Thermolytic Mechanism of Serine

作　　者：黎新[1] 颜肖慈[2] 刘义[2] 罗明道[2] 屈松生[2] 

机构地区：[1]渝西学院化学与环境科学系,永川402168 [2]武汉大学化学与分子科学学院,武汉430072

出　　处：《Chinese Journal of Chemical Physics》2003年第3期232-236,共5页化学物理学报（英文）

基　　金：国家自然科学基金资助项目 ( 3 9470 0 0 8)

摘　　要：用热重法 (TG)、差热分析 (DTA)和红外光谱 (IR)方法测试了丝氨酸的热分解过程 ,用量子化学方法在RHF/6 2 1G水平上全优化计算了丝氨酸及其热分解中间产物、产物分子的几何构型 ,得到其总能量和Mulliken集居数等数据 .从理论上证明了环氧中间产物的存在 .通过对实验结果和计算结果如Mulliken集居数的分析 ,提出了丝氨酸的热分解反应机理是先失去CO2 为主要反应通道 。The thermolytic process of serine is tested by thermogravimetry(TG), differential thermal analysis (DAT) and infrared spectrum(IR) methods. The thermolysis of the serine after the loss of the CO2 is Very complicated and it is hard to obtain thermolytic reaction mechanism by experimental testing methods. Thus, the thermolytic reaction mechanism of serine is theoretically deduced by ab initio calculation method of quantum chemistry. The parameters of the total energy and Mulliken population are obtained by the optimized calculation on the geometries of serine, its thermolytic intermediate and final products respectively at the RHF/6-21 G level. The calculation of epoxy intermediate is optimized by directly inputting into computer molecular fragments of serine after its loss of NH3. Oscillation analysis is made on the epoxy intermediate and the results indicate that the structure of epoxy intermediate is a stable structure., but not a non-saddlepoint transition state. The obtained results are consistent with what is stated in the documents concerned. However, in Ratliff's documents, the production of epoxy intermediate in the thermolytic process of serine is only a supposition rather than based on either experimental test or theoretical deduction. Here the existence of epoxy intermediate is proved theoretically. Through the analysis of the results of the experiment and calculation, the thermolytic reaction mechanism is put forward: the thermolysis of serine is Performed with the loss of CO2 as the main reaction channel and accompanied by the secondary reaction with the production of epoxy intermediate after the loss of NH3. Furthermore, a comparison is made between ab initio calculation method and semiempirical method. It's proved that both methods can result in reasonable conclusion concerning the thermolysis of serine, however, the former has an advantage. In deducing the thermolytic reaction mechanism of serine by semiempirical method, not only is bond order used, but also localized orbital energy is required to

关 键 词：丝氨酸 热分解反应机理 从头算 

分 类 号：O643.1[理学—物理化学]