用过渡态理论研究O(~3P)原子和酮类分子反应速率常数

THE EXTRAPOLATION OF RATE CONSTANTS FOR REACTION OF O(3~P) WITH KETONES USING TRANSITION-STATE THEORY

酮类分子反应是大气化学反应中的一个中间反应.在300--500K范围内,我们对酮类分子和O(~3P)原子反应速率常数作了系列测定.为了估算大气化学和燃烧化学反应条件下的反应速率常数,本文用过渡态理论将实验结果外推到200—2000K范围内.

Conventional transition-state theory is used for extrapolating rate constant of re-actions of O(~3P) atom with ketones to temperature range 200--2000K. Estimationsof structural properties of the activated complex necessary for calculating free energyof activation are presented. Expressions of the rate constant with three parametersare derived. These are as follows (unit: cm^(-3)·molecule^(-1). s^(-1)). k = 5.34×10^(-20)T^(2.96)exp (-12.4/RT) (for butanone) k = 6.64×10^(-19)T^(2.67)exp (-14.1/RT) (for 3-pentanone) k = 3.54×10^(-23)T^(3.88)exp (-0.29/RT) (for iso-butyl ketone) k = 1.29×10^(-18)T^(2.60)exp (-16.6/RT) (for 3.3-2 methyl-2-butanone) k = 9.47×10^(-21)T^(3.23)exp (-9.71/RT) (for c-pentanone) k = 5.23×10^(-20)T^(3.18)exp (-9.92/RT) (for c-hexanone) k^(a) = 1.87×10^(-18)T^(2.52)exp (-29.5/RT) (for acetone) k^(b) = 3.21×10^(-18)T^(2.15)exp (-25.6/RT) (for acetone)Note: (a) the frequency of C·H·O bend vibration is 200 cm^(-1). (b) the frequency of C·H·O bend vibration is 700 cm^(-1).