【摘要】 以重质有机资源热解过程中的自由基反应为背景,为了探究自由基对共价键的诱导作用及其对共价键解离能的影响,采用基于密度泛函理论的研究方法,选择ωB97XD/6-31G**级别在Gaussian 09程序上对·CH3、·OH和·H分别诱导七类共价键反应过程的能量进行了理论计算。结果表明,空间位阻效应对自由基诱导反应能垒的影响占主要地位,共价键种类的影响相对次要;不存在·OH和·H的同基团诱导交换反应时,·OH诱导能垒比·H的高约40 kJ/mol,·CH3比·OH、·H的诱导能垒分别高约为50、90 kJ/mol;存在·OH或·H的同基团诱导交换反应时,会导致能垒约有70 kJ/mol的提高,在计算时应判断诱导反应的具体情况并加以修正。可以利用上述值估算不同共价键诱导反应的能垒。更多还原

【Abstract】 With the free radical reaction during the pyrolysis process of heavy organics as the background,the research approach based on density functional theory was adopted to exploring the induction of free radicals on covalent bond and its effect on covalent bond dissociation energy. The energies of seven kinds of covalent bond reactions induced respectively by ·CH3,·OH and ·H were calculated theoretically on the Gaussian 09 program at the level of ωB97 XD/6-31 G**. The results indicate that the steric hindrance effect plays a significant role in the energy barrier of free radical induced reaction,while the influence of the covalent bond type plays a minor role. When the isogroup induced exchange reaction of ·OH and ·H does not proceed,the induced energy barrier of ·OH is about40 kJ/mol higher than that of ·H and the induced energy barrier of ·CH3 is about 50 and 90 kJ/mol higher than that of ·OH and ·H respectively. When the isogroup induced exchange reaction of ·OH and ·H works,it will result in the increasing of 70 kJ/mol of the energy barrier. During the process of calculation,the specific situation of induced reaction should be judged and revised. The above values can be used to estimate the energy barriers of different covalent bond induced reactions.更多还原