Mechanism and Thermal Rate Constants for the Complete Series Reactions of Chlorophenols with H

作者：Zhang Qingzhu^*; Qu Xiaohui; Wang Hui; Xu Fei; Shi Xiangyan; Wang Wenxing

来源：Environmental Science & Technology, 2009, 43(11): 4105-4112.

DOI：10.1021/es9001778

Reactions of chlorophenols with atomic H are important initial steps for the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in incinerators. Detailed insight into the mechanism and kinetic properties of crucial elementary steps is a prerequisite for understanding the formation of PCDD/Fs. In this paper, the complete series reactions of 19 chlorophenol congeners with atomic H have been studied theoretically using the density functional theory (DFT) method and the direct dynamics method. The profiles of the potential energy surface were constructed at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. Modeling of the PCDD/Fs formation requires kinetic information about the elemental reactions. The rate constants were deduced over a wide temperature range of 600 similar to 1200 K using canonical variational transition-state theory (CVT) with small curvature tunneling contribution (SCT). The rate-temperature formulas were fitted for the first time. This study shows that the substitution pattern of the phenol has a significant effect on the strength and reactivity of the O-H bonds in chlorophenols. Intramolecular hydrogen bonding plays a decisive role in determining the reactivity of the O-H bonds for ortho-substituted phenols.

• 出版日期2009-6-1
• 单位山东大学; 清华大学