Kinetics of the Photobromination of Dichloro- and Dibromoethane. Estimate of the C–H Bond Dissociation Energies and the Heats of Formation of the CH<sub>3</sub>CCl<sub>2</sub>and CH<sub>3</sub>CBr<sub>2</sub>Radicals
作者:Kikuo Miyokawa、Eugene Tschuikow-Roux
DOI:10.1246/bcsj.72.1
日期:1999.1
8(σ)] × 1011exp[(−7300 ± 360 cal mol−1)/RT] and k2 = [2.2 ± 1.2(σ)] × 1011exp[(−7110 ± 360 cal mol−1)/RT]. Using a justifiable approximation concerning the magnitude of the activation energies for the reverse reaction, the following thermochemical quantities (kcal mol−1) were derived: ΔH°f(CH3CCl2) = 11.9 ± 1.2, D°(CH3CCl2-H) = 95.1 ± 1.2, ΔH°f(CH3CBr2) = 33.5 ± 1.3, D°(CH3CBr2-H) = 94.9 ± 1.2. The relation
使用氯乙烷和乙烷在 308-368 K 的温度范围内研究了 α-H 提取反应 RH + Br → R + HBr、RH = 1,1-二氯 (1) 和 1,1-二溴乙烷 (2) 的动力学分别作为外部竞争对手。将相对速率与氯乙烷和乙烷的已知速率参数相结合以获得绝对速率常数 (cm3 mol−1 s−1): k1 = [6.9 ± 3.8(σ)] × 1011exp[(−7300 ± 360 cal mol −1)/RT] 和 k2 = [2.2 ± 1.2(σ)] × 1011exp[(−7110 ± 360 cal mol−1)/RT]。使用关于逆反应活化能大小的合理近似,推导出以下热化学量 (kcal mol−1):ΔH°f(CH3CCl2) = 11.9 ± 1.2, D°(CH3CCl2-H) = 95.1 ± 1.2, ΔH°f(CH3CBr2) = 33.5 ± 1.3, D°(CH3CBr2-H)