Waddington反应机理中β-断键反应类动力学研究  

Kinetic study of β-scission reaction class in Waddington reaction mechanism

作　　者：许诗敏 孙晓慧 李永青 王静波[1] 李泽荣[2] XU Shi-min;SUN Xiao-hui;LI Yong-qing;WANG Jing-bo;LI Ze-rong(College of Chemical Engineering,Sichuan University,Chengdu 610065,China;College of Chemistry,Sichuan University,Chengdu 610064,China)

机构地区：[1]四川大学化学工程学院,四川成都610065 [2]四川大学化学学院,四川成都610064

出　　处：《化学研究与应用》2020年第6期1060-1066,共7页Chemical Research and Application

基　　金：国家自然科学基金项目(91641120)资助。

摘　　要：β-羟基烷基过氧自由基(β-HOROO·)是烯烃低温燃烧的主要中间体,其主要消耗通道为Waddington反应通道,即首先分子内发生1,5-H迁移生成β-氢过氧烷氧自由基(β-HOORO·),随后β-HOORO·发生β-断键生成醛(或酮)和OH自由基。本文针对该反应通道的第二步反应,对不同烷基R的β-HOORO·的β-断键反应类的动力学开展了系统研究。对该反应类,根据β-HOORO中连接-OOH的C原子(C-OOH)和连接-O·的C原子(C-O·)类型不同,划分为不同子类,并对每一子类选取不同取代基大小作为代表反应,开展了能垒和速率常数的规律研究。物种几何结构优化和反应能垒的计算均在M06-2X/6-311++G(d,p)水平进行,反应的高压极限速率常数则采用过渡态理论计算。本文构建了该类反应的速率规则和Evan-Polanyi线性自由能关系,考察了C-OOH和C-O·不同类型以及取代基大小对反应动力学参数的影响。本文的研究为烯烃低温燃烧中重要的β-HOORO·发生β-断键反应类提供了准确的动力学参数,有助于烯烃燃烧详细机理的构建以及机理自动生成。β-hydroxyalkylperoxy radicals(β-HOROO·)are the main intermediates in the low-temperature combustion process of alkene,the main consumption channel of which is Waddington reaction channel.Waddington reaction mechanism includes two elementary reaction steps:1.β-hydroperoxyalkoxy radical(β-HOORO·)is formed by the intermolecular 1,5-H shift of β-HOROO·,2.followed by β-scission of the β-HOORO·and the aldehydes(or ketones)and OH radical are formed.In this paper,the kinetics of β-scission reactions of β-HOORO·with different alkyl(R)was studied systematically.According to the different types of C atoms connected to-OOH(C-OOH)and connected to-O·(C-O·)in β-HOORO·,the reaction class could be divided into different subclasses.Different substituent sizes were selected as representative reactions for each subclass,and the laws of energy barrier and rate constant were studied.Geometries for all species were optimized by M06-2X/6-311++G(d,p)method and reaction energy barriers were calculated by the same level.The transition state theory was used to calculate the high-pressure limit rate constants of all reactions.In this paper,the rate rule and Evan-polyanyi linear free energy relationship of this reaction class were constructed,and the effects of different types of C-OOH and C-O·and the size of substituents on the kinetic parameters were investigated.The present work provided accurate kinetic parameters for reaction class of β-scission of the β-HOORO·,which are important for the alkene combustion modeling at low temperature.This work would be helpful for the construction of detailed combustion mechanism and the mechanism automatic generation of alkene.

关 键 词：Waddington反应 β-断键 过渡态理论 速率规则 Evan-Polanyi线性自由能关系 

分 类 号：O643.2[理学—物理化学]