丁基乙烯基醚和臭氧反应机理的DFT研究

Density functional theory studies on the mechanism of ozonolysis of butyl vinyl ether

本文采用BHandHLYP和MPWB1K方法结合6-31+G(d,p)基组,对臭氧与丁基乙烯基醚三种同分异构体(n-Bve、i-Bve和t-Bve)的反应机理进行了研究,优化了反应势能面上各驻点的几何构型,用内禀反应坐标(IRC)计算和频率分析方法对过渡态进行了验证.结果表明,在臭氧与丁基乙烯基醚反应中,随着丁基基团空间位阻的变化,生成OH自由基的几率发生改变.臭氧与丁基乙烯基醚之间具有较高的反应活性,二者反应很容易生成较稳定的环合中间体,且为放热反应.其中臭氧化异丁基乙烯基醚的活化能最高,臭氧化正丁基乙烯基醚的活化能最低,理论计算得到的反应势垒与相应的实验值相吻合.

The reaction mechanism of ozonolysis of three isomers of butyl vinyl ether （n-Bve, i-Bve and t-Bve） has been studied using the density functional theory （DFT） at the BHandHLYP/6-31＋G（d,p） and MPWB1K/6-31＋G（d,p） levels of theory. The geometries for the reactants, the transition states and the products are completely optimized. All the transition states are verified by the vibrational analysis and the instrisic reaction coordinate （IRC） calculations. The pathway of rearranging to isomer is preferred to the pathway of decomposing to OH for the n-butyl,/-butyl and t-butyl substituted carbonyl oxide compounds. Our computations produce the large exothermicity of the three cycloaddition reactions. According to our calculation, the ozone-n-Bye reaction is faster than the ozone-t-Bve reaction, the ozone-i-Bve reaction is slower than the ozone-t-Bve reaction. The calculated results are in good agreement with the available experiment data.