National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China.
J Phys Chem A. 2012 Jan 12;116(1):55-63. doi: 10.1021/jp207978n. Epub 2011 Dec 23.
The unimolecular decomposition processes of ethylene glycol have been investigated with the QCISD(T) method with geometries optimized at the B3LYP/6-311++G(d,p) level. Among the decomposition channels identified, the H(2)O-elimination channels have the lowest barriers, and the C-C bond dissociation is the lowest-energy dissociation channel among the barrierless reactions (the direct bond cleavage reactions). The temperature and pressure dependent rate constant calculations show that the H(2)O-elimination reactions are predominant at low temperature, whereas at high temperature, the direct C-C bond dissociation reaction is dominant. At 1 atm, in the temperature range 500-2000 K, the calculated rate constant is expressed to be 7.63 × 10(47)T(-10.38) exp(-42262/T) for the channel CH(2)OHCH(2)OH → CH(2)CHOH + H(2)O, and 2.48 × 10(51)T(-11.58) exp(-43593/T) for the channel CH(2)OHCH(2)OH → CH(3)CHO + H(2)O, whereas for the direct bond dissociation reaction CH(2)OHCH(2)OH → CH(2)OH + CH(2)OH the rate constant expression is 1.04 × 10(71)T(-16.16) exp(-52414/T).
已经用 QCISD(T)方法结合 B3LYP/6-311++G(d,p)水平下的几何优化研究了乙二醇的单分子分解过程。在所确定的分解通道中，H(2)O 消除通道的势垒最低，而在无势垒反应（直接键断裂反应）中，C-C 键的离解是能量最低的解离通道。温度和压力相关速率常数的计算表明，在低温下，H(2)O 消除反应占主导地位，而在高温下，直接 C-C 键解离反应占主导地位。在 1 大气压下，在 500-2000 K 的温度范围内，对于通道 CH(2)OHCH(2)OH → CH(2)CHOH + H(2)O，计算得到的速率常数表达式为 7.63×10(47)T(-10.38) exp(-42262/T)，对于通道 CH(2)OHCH(2)OH → CH(3)CHO + H(2)O，计算得到的速率常数表达式为 2.48×10(51)T(-11.58) exp(-43593/T)，而对于直接键解离反应 CH(2)OHCH(2)OH → CH(2)OH + CH(2)OH，速率常数表达式为 1.04×10(71)T(-16.16) exp(-52414/T)。
