附件2 粒大浮 教 案 2003~~2004学年第Ⅰ学期 院(系、所、部)化学与环境学院有机化学研究所 教研室有机化学 课程名称有机化学(双语教学 授课对象化学教育 授课教师杨定乔 职称职务教授 教材名称 Organic Chemistry 2003年09月01日
附件 2 教 案 2003~~ 2004 学年 第 I 学期 院（系、所、部）化学与环境学院有机化学研究所 教 研 室 有机化学 课 程 名 称 有机化学(双语教学) 授 课 对 象 化学教育 授 课 教 师 杨定乔 职 称 职 务 教授 教 材 名 称 Organic Chemistry 2003 年 09 月 01 日
有机化学(双语教学)课程教案 授课题目(教学章节或主题):第七章·芳烃授课类型理论课 Aromatic Compounds 授课时间第8周第29-36节 教学目标或要求:了解苯的结构及芳烃的异构现象和苯环的亲电取代定位效应的基本 理论。掌握苯环的亲电取代反应及其反应机理 教学内容(包括基本内容、重点、难点) Arenes Nomenclature Monosubstituted benzene derivatives are names as other hy drocarbons using the following set of rules 1. Benzene is the parent name; when a benzene ring is a substituent on another chain, it is referred to as a CH3 methylbenzene 1-pheny]heptane bromobenzene ethylbenzene or toluene 2. Disubstituted benzenes are named using ortho para-and meta- to describe the substitution pattern (1, 2 1, 4 and 1, 3 respectively or simply by num bering the substituents
有机化学(双语教学) 课程教案 授 课 题 目（ 教 学 章节 或 主题 ）：第 七 章 ．芳 烃 （Aromatic Compounds） 授课类型 理论课 授课时间 第 8 周第 29-36 节 教学目标或要求：了解苯的结构及芳烃的异构现象和苯环的亲电取代定位效应的基本 理论。掌握苯环的亲电取代反应及其反应机理。 教学内容（包括基本内容、重点、难点）： Arenes: Nomenclature Monosubstituted benzene derivatives are names as other hydrocarbons using the following set of rules: 1. Benzene is the parent name; when a benzene ring is a substituent on another chain, it is referred to as a "phenyl" group. 2. Disubstituted benzenes are named using ortho-, para- and meta- to describe the substitution pattern (1,2 1,4 and 1,3 respectively) or simply by numbering the substituents
1, 3-diethylbenzel CH2CH3 ortho-dibromobenze para-dimethylbenzene or 1.2-dibromoben 1, 4-dimethylbenzene or para-Iylene 3. Substituents are num bered to give the lo west possib le num ber sequence at the first point of difference assigning priorities alphabetically if there is a"tie". 1-chloro-3, 5-diethylbenzene There are also a large number of common (or trivial") names for arenes which are in common usage and students should strive to recognize these by both systematic and common names H NH. H aniline phenol nitrobenzene is these is used as the parent chain, the substituent is position #1, br he Many of these are acceptable parents" with regard to nomenclature. When definit
3. Substituents are numbered to give the lowest possible number sequence at the first point of difference, assigning priorities alphabetically if there is a "tie". There are also a large number of common (or "trivial") names for arenes which are in common usage and students should strive to recognize these by both systematic and common names. Many of these are acceptable "parents" with regard to nomenclature. When one is these is used as the parent chain, the substituent is position #1, by definition
CH3 2-chloro- nitrotoluene 2 chloro-4-nitrotolpene H NO 5chloro-2-nitrotolpene More examples: 4-bromo-12-dime thylbenzene 3chloro-1-me thylbenzene au l-methyl-4-nitrobenzene cu nitrotoluene 2-chloro-1-ethyh4-nitrobenzene l-chloro-2-ethyh-nitrobemzene 4chloro-2-ethyhI-nitrobenzene Arenes: Aromatic Systems and the 4n+2 Rule
More Examples: Arenes: Aromatic Systems and the 4n+2 Rule
Benzene, having the molecular formula C h, would be consistent with a structure such as cyclohexatriene, having three con jugated double bonds in a six-membered ring. The compound is, however, far more stable than would be predicted for a triene, based on the heat of hydrogenation (the energy evolved when one mole of compound is reacted with H, in the presence of Pt or Pd catalyst. As shown below, the inclusion of additional double bonds in a compound is generally associated with an increase in the heat of hydrogenation of approximately 25 kcal/mole; benzene, however, has a heat of hydrogenation which is less than that of cyclohexadiene. Further, benzene does not undergo typical alkene reactions; it will not react with Br, to form a dibromide, nor will it react with halogen acids (i. e, Hcl) to give alkyl halides Heat of Hydrogenation (energy released duning reduction with HyPt Reactant Prodnct AH° Cyclohexene Cyclohexane 28.6 kcallmole 1 3-Cyclohexadieneene Cyclohexane 55.4 kcal'mole Cyclone xane 49.8 kcal mole H2iPt 86 kcal' mole expected: 50 kcallmole observed 36 kcalhmole more stable than expected The rationalization for the unusual reactivity of benzene which is generally accepted today is that the conjugated T-system forms a continuous molecular orbital above and below the plane of the ring, and that this planar, continuous T-System containing six electrons has unusual stability. The delocalization of the electrons is typically shown by writing resonance forms in which the double bonds in benzene compounds can be shown to be distributed equally among 11 carbon centers (shown below for dibromobenzene). Remember that resonance forms represent structural limits and that the molecule is"never"one form or the other but is a hybrid of both. To show this, the bonding in benzene compounds is often written as a circle within the ring, although this type of structural representation has its own drawbacks, as we will see when we consider substitution reactions
Benzene, having the molecular formula C6H6, would be consistent with a structure such as cyclohexatriene, having three conjugated double bonds in a six-membered ring. The compound is, however, far more stable than would be predicted for a triene, based on the heat of hydrogenation (the energy evolved when one mole of compound is reacted with H2 in the presence of Pt or Pd catalyst. As shown below, the inclusion of additional double bonds in a compound is generally associated with an increase in the heat of hydrogenation of approximately 25 kcal/mole; benzene, however, has a heat of hydrogenation which is less than that of cyclohexadiene. Further, benzene does not undergo "typical" alkene reactions; it will not react with Br2 to form a dibromide, nor will it react with halogen acids (i.e., HCl) to give alkyl halides. The rationalization for the unusual reactivity of benzene which is generally accepted today is that the conjugated −system forms a continuous molecular orbital above and below the plane of the ring, and that this planar, continuous −system containing six electrons has unusual stability. The delocalization of the electrons is typically shown by writing resonance forms in which the double bonds in benzene compounds can be shown to be distributed equally among all carbon centers (shown below for dibromobenzene). Remember that resonance forms represent structural limits and that the molecule is "never" one form or the other, but is a hybrid of both. To show this, the bonding in benzene compounds is often written as a circle within the ring, although this type of structural representation has its own drawbacks, as we will see when we consider substitution reactions