CH3CH2O＋HCHO 反应机理及主通道速率常数

Mechanistic Studies on CH_3CH_2O + HCHO Reaction and Rate Constants of Major Channel

采用 CCSD（T）/ cc-pVDZ// B3LYP/6-311＋＋G（d,p）双水平计算方法研究了 CH3 CH2 O＋HCHO 反应的微观反应机理.结果表明,标题反应主要存在5个抽氢和3个氢迁移异构化反应通道,其中抽氢通道 R→IMa（CH3 CH2 O…CH2 O）→TS1→ IM1b→P1（CH3 CH2 OH＋CHO）为优势通道,其表观活化能为14.65 kJ/ mol.利用变分过渡态理论（CVT）并结合小曲率隧道效应模型计算了主通道 R1在275~1000 K 温度范围内的速率常数 kTST , kCVT 和 kCVT/ SCT ,在此温度区间内表观反应速率常数三参数表达式为 kCVT/ SCT =2.26×10-17 T0.57 exp（-1004/ T）,显示具有正温度系数效应.

The mechanism of the reaction between CH3 CH2 O and HCHO was investigated at CCSD（T） cc-pVDZ/ / B3LYP/ 6-311＋＋G（ d,p） level. Eight possible reaction channels（ five H-abstraction channels and three H-isomerization channels） for the title reaction were identified. The results indicated that channel R→IMa（CH3 CH2 O…CH2 O）→TS1→IM1b→P1（CH3 CH2 OH＋CHO） was the most favorable channel with the apparent activation energy of 14. 65 kJ/ mol. The rate constants of the path R1 were evaluated over a tempera-ture range of 275-1000 K via the canonical variational transition state theory（CVT） combined with a small-curvature tunneling correction. The fitted three-parameter expression for the path R1 is kCVT/ SCT = 2. 26×10-17 T0. 57 exp（-1004 / T） and R1 has a positive temperature effect over a temperature range of 275-1000 K.