C_(70)与臭氧反应机理的理论研究  

Theoretical Studies on the Mechanism of the Reaction of C_(70) with Ozone

作　　者：夏树伟[1] 梁玉华[2] 陈兰[3] 潘荫明[3] 赵学庄[3] 唐敖庆[4] 

机构地区：[1]中国海洋大学化学化工学院,青岛266003 [2]青岛科技大学应用化学系,青岛266042 [3]南开大学化学系,天津300071 [4]吉林大学理论化学研究所,长春130023

出　　处：《化学学报》2003年第6期824-834,共11页Acta Chimica Sinica

基　　金：国家自然科学基金 (No.2 97730 2 2 )资助项目

摘　　要：用半经验AM1方法研究了C70 与臭氧环加成反应的反应机理 .采用Berny梯度法优化得到反应的过渡态 ,并进行了振动分析确认 .计算结果表明 :臭氧在C70 6 6单、双键上的环加成反应均为复杂反应 ,由三步组成 :第一步是O3 分子与C70的 6 6单、双键发生 1,3 偶极环加成反应 ,生成分子臭氧化物 (即中间体I) ,6 6双键加成为放热反应 ,6 6单键加成为吸热反应 ,活化势垒分别为 84 7和 181 2kJ·mol-1;第二步是中间体I的加成 ,C—C键断裂 ,生成两性离子中间体II的放热反应 ,其势垒分别为 61 3和 13 3kJ·mol-1;第三步是中间体II脱去一个O2 分子生成具有环氧结构的C70 O ,均为放热反应 ,活化势垒分别为 169 3和 10 1.2kJ·mol-1.从反应机理和动力学角度解释了 6 6双键加成优于 6 6单键加成的原因 .O3 分子与C70 6 6双键的加成反应是协同且同步进行的 ,与 6Cycloaddition reaction of ozone to C-70 has been studied by using the semi-empirical method AM1. A reasonable mechanism of the reaction has been suggested. All the geometries of the stationary points on the reaction path were optimized by energy gradient technique and the transition states were characterized by vibration frequency analysis. The calculation results show that the cycloaddition. of ozone on 6-6 double and single bonds of C-70 are complicated reactions. Three steps are involved in the reaction mechanism: (1) A molecular ozonide (intermediate (I)) is formed by 1, 3-dipolar cycloaddition process. The addition on 6-6 double bond is an exothermal reaction, while the addition of 6-6 single bond is an endothermic reaction. The barriers of 6-6 double and single bonds are 84.7 and 181.2 kJ.mol(-1) respectively. (2) Cleavage of the C-C bond formed in the addition in intermediate (I) leads to the formation of a zwitterionic intermediate (II), which is an exothermal reaction. The barriers of 6-6 double and single bonds are 61.3 and 13.3 kJ.mol(-1), respectively. (3) One O-2 molecule is eliminated from intermediate (II) resulting in the formation of C70O with an epoxide structure. Both the addition of 6-6 double and single bonds are exothermic reactions and the barriers are 169.3 and 101.2 kJ . mol(-1), respectively. The reasons that ozone cycloaddition should take place across 6-6 double bond rather than 6-6 single bond of C-70 are explained by the reaction mechanism and kinetic factors. The addition of ozone on 6-6 double bond of C-70 in the first step is a concerted synchronous process, while the addition of 6-6 single bond is a concerted unsynchronous process.

关 键 词：C70 臭氧 反应机理 理论研究 环加成反应 Berny梯度法 过渡态 富勒烯 碳70 AMl方法 

分 类 号：O643.1[理学—物理化学]