级炔二烯烃脂环烃.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 写出环戊烯与下列试剂反应的产物： 练习 用化学方法区别下列化合物： 1 2-甲基丁烯 甲基环己烷 1,2-二甲基环丙烷 2 丙烷 环丙烷 丙烯 丙炔 A B C 练习 用化学方法区别下列化合物： 1 2-甲基丁烯 甲基环己烷 1,2-二甲基环丙烷 2 丙烷 环丙烷 丙烯 丙炔 A B C D 四、脂环烃的结构特点及稳定性 （一）稳定性的规律 三、四元环不稳定 五元环较稳定 六元稳定 （二）稳定性规律的解释 1、张力学说（拜尔） 2、现代结构理论（共价键的成键特点） 脂环烃 Cyclic Hydrocarbons 重点和难点 脂环烃的结构与稳定性的关系： A 环丙烷及其衍生物：环丙烷的角张力较高，具有较高的张力能，为一个张力环。 B 环丁烷及其衍生物：环丁烷具有较强的角张力，弱的扭转力，有较高的张力能，也是张力环，但较环丙烷稳定。 C 环戊烷及其衍生物：基本无角张力，扭转力较弱，张力能不大，化学性质较稳定 D 环己烷及其衍生物：无角张力，为无张力环，环系稳定，化学性质最稳定。 结构特点 C：sp3 1、环丙烷 环烷烃的顺反异构 bp. 37℃ bp. 29℃ 顺-1,2-二甲基环丙烷 反-1,2-二甲基环丙烷 环己烷构象 ? ? ? ? ? ? ? ? ? ? ? ? chair conformation boat conformation chair conformation chair conformation boat conformation ? 两种椅型构象转换 a e 一元取代的环己烷 e-结构稳定 二元取代的环己烷 e,e-反式结构稳定 十氢化萘 In the compounds that we have studied so far,the carbon atoms,which are attached to one another to form chains,are called open-chain compounds. In many compounds,however,the carbon atoms form ring,which arecalled cyclic compounds. In this chapter we shall take up cyclic compounds including aliphatic compounds. Much of the chemistry of alicyclic compounds already know, since it is essentiall the chemistry of their open-chain counterparts :a cycloalkane, for example, is an alkane, and in general acts like one. But the cyclic nayure of some of there compounds confers very special properties on them. It was here that the study of conformational analysis had its real beginning, and it is here that we, in turn, can begin to appreciate the practical importance of this branch of stereochemiatry. Being a ring or several rings-places restrictions on the shape a molecule can assume, or on just where solvent molecules can cluster; steric hindrance can be increased or decreased; the attack by a reagent can be limited to just one direction. The very size of the ring can lead to unusual reactivity. We shall focus our at