摘要
采用密度泛函理论B3LYP方法，在6—311＋G（d，P）基组水平上研究了二甲亚砜（DMSO）与XO（X=Cl，Br）自由基反应的微观动力学机理，并利用经过wigner校正的传统过渡态理论计算了标题反应在200-2000K温度范围内的反应速率常数。研究结果表明，DMSO与XO（X=Cl，Br）自由基反应主要有氧转移和抽氢两种反应机理，氧转移反应的能垒显著低于抽氢反应，且前者为放热反应后者为吸热反应；低温时氧转移反应占绝对优势，298K时DMSO与XO（X=Cl，Br）两个反应体系的总速率常数分别为2．09×10^15和1.75×10^-14cm^3·molecule^-1·s^-1，氧转移反应分支比均为100％。高温时抽氢反应上升为主通道。2000K时其总速率常数分别为6．32×10^-12和8．41×10^-12cm^3·molecule^-1·s^-1，抽氢反应分支比分别为91．8％和79．4％。
Theoretical investigations are carried out on the reaction CH3 SOCH3 ＋ XO （ X = Cl, Br） by means of the density function theory method B3LYP with 6-311 ＋ G （d, p） basis set. Two reaction pathways were considered： （1） the oxygen-atom transfer （OAT） by XO（X =Cl, Br） to form X and dimethylsulfone（CH3SO2CH3 ） and （2） the abstraction of hrdrogen by XO（X = Cl, Br） to form HOX and CH3 SOCH2. All the OAT reactions were exothermic and the abstraction of hrdrogen reactions were endothermic. The rate constants of the title reaction were calculated by the conventional transition state theory with wigner correction in a wide temperature range 200 -2000K. At 298K, the total rate constants of the two reactions were 2.09 ×10^-15 and 1.75 × 10^-14 cm^3 · moleculel ^-1·s^-l. The branching ratios of the both oxygen-atom transfer reactions were 100%. With the temperature increasing, the abstraction of hrdrogen reaction became dominate. At 2000K, the total rate constants of the two reactions were 6.32 ×10^-12 and 8.41× 10^-12 cm^3 · molecule^-1·s^-l , the branching ratios of the abstraction of hrdrogen reactions were 91.8% and 79.4%.
出处
《化学研究与应用》
CAS
CSCD
北大核心
2007年第2期161-168,共8页
Chemical Research and Application
基金
陕西省自然科学基金资助项目(2006B12)
