吡啶光氯化反应的量子化学研究(1)──PM3计算吡啶静态结构和氯代位置

The Quantum Chem istry Study on the Photochem icalChlorination of Pyridine(1) the calculation ofpyridine structure and chlorolocation by PM3

用半经验量子化学程序ＰＭ３对吡啶分子基态及第一激发态做了结构全优化计算，得到吡啶基态及第一激发态的分子轨道和其相应的能量，同时得到吡啶环各碳原子的电荷密度、成键度和自由价． 计算结果表明， Ｃｌ·与吡啶基态分子发生取代反应，优先生成２－氯吡啶，Ｃｌ·与吡啶激发态分子反应，优先生成４－氯吡啶．

The geom etry structures ofpyridine m olecule in the ground state and the firstex- cited state are optim ized by m eans of sem iem pirical quantum chem istry program m e-PM3. The m olecular orbitals and their energy ofpyridine in the ground state and the firstexcited state are obtained. And the electron density and bond valence of each carbon atom in pyri- dine m olecule are obtained, too. The result show s that chlorine radicalreacting w ith pyri- dine m olecule in ground state w illpreferablely produce 2-chloropyridine and reacting w ith pyridine m olecule in the firstexcited state w illproduce 4-chloropyridine.