有机化合物分子的结构基础.ppt

1、第一章,有机化合物分子的结构基础,第一章重点讲解问题,1. 简要回顾有机化学的形成，并回答有机化学是怎样的一门学科 2. 价键理论基础回顾和分子轨道理论简介 3. 杂化轨道理论与有机化合物结构特点 4. 有机化合物的基本骨架和官能团 5. 有机化合物的结构与性质的关系 1、价键 2、非共价力 3、立体结构 6. 质子酸碱和路易斯酸碱理论,1.1 有机化学及其发展历史和趋势,1. History In 1770, Swedish chemist Torberm Bergman was the first to express the difference between “organic” an

2、d “inorganic”substances,1.1 有机化学及其发展历史和趋势,Organic - derived from living organism Originally, Study of compounds extracted from living organisms and their natural products,1.1 有机化学及其发展历史和趋势,Vital force theory: Organic compounds needs a “vital force” to create them,1.1 有机化学及其发展历史和趋势,In 1828, Fridrich

3、Wohler convert the “inorganic” salt ammonium cyanate into the “organic” substance urea,1.1 有机化学及其发展历史和趋势,Wohlers synthesis led to the realization that molecules found in nature can be described, handled, and synthesized in the same way as minerals and metals. What an astounding insight-that atoms an

4、d molecules move freely between the living and nonliving worlds, that the living and nonliving share fundamental attributes that can be studied. With this discovery, organic chemistry was born.,1.1 有机化学及其发展历史和趋势,作业 1： 查阅有关书籍和文献，了解有机化学的发展历史和趋势。并就发展历史中可以称之为里程碑的一个发现作介绍和评述。 字数要求在1500字以内,第六周周三交,1.1 有机化学及

5、其发展历史和趋势,2. Definition of Organic Chemistry Organic Chemistry is the Chemistry of Carbon Compounds,Organic Chemistry is the Chemistry of Carbon Compounds,Question: Why is an entire branch of chemistry devoted to the study of carbon-containing compounds?,Organic Chemistry is the Chemistry of Carbon C

6、ompounds,The answer is : Carbon-containing compounds makes life possible We need carbon-containing compounds in nature for our food, medicines, clothing, and energy We depend on millions of synthetic carbon -contaning compounds in our daily life,Organic Chemistry is the Chemistry of Carbon Compounds

7、,Question: What makes carbon so special? Why are there so many carbon-containing compounds?,Organic Chemistry is the Chemistry of Carbon Compounds,Please try to draw out all the structures corresponding to the formula: a. C2H6O b. C3H6O,It shares electrons with other carbon atoms It shares electrons

8、 with several kinds of atoms C-C single, double and triple bond chain, or cyclo-links Isomerism phenomenon,1.2 价键理论基础回顾和分子轨道理论简介,1.2.1 The Structure of an Atom 1.2.2 Distribution of Electrons in an Atom Atomic orbitals:,1.2 价键理论基础回顾和分子轨道理论简介,(1) The aufbau priciple The closer the orbital is to the n

9、ucleus, the lower its energy 1s2s2p3s3p4s3d4p5s4d5p6s (2) The Pauli exclusion priciple Degenerate orbitals - have the same energy (3) Hunds rule C: 1s2 2s2 2px12py12pz0,1.2 价键理论基础回顾和分子轨道理论简介,1.2.3 Ionic, Covalent, and Polar Bonds An atom is most stable if it has a filled shell or an outer shell of e

10、ight electrons and no electrons of higher energy Ionic bond: LiCl Covalent bond: H2, O2, CO2 C: 1s2 2s2 2px12py12pz0 Neither readily gives up electrons Nor readily accepts electrons Nonpolar bond (H-H)and Polar bond ( C-H, C-O ),1.2 价键理论基础回顾和分子轨道理论简介,常见价键的表示方法： Lewis Structures Kekule Structures Con

11、densed Structures,HCO2H,1.2 价键理论基础回顾和分子轨道理论简介,思考题 共价键化合物与离子键化合物性质有哪些差异？ 请记住有机化合物中常见元素的电负性 Electronegativity: H: 2.1 B: 2.0 C: 2.5 N: 3.0 O: 3.5 F: 4.0 Cl: 3.0 Br: 2.8 I: 2.5 Li: 1.0 Mg: 1.2,1.2 价键理论基础回顾和分子轨道理论简介,1.2.4 Introduction of Molecular Theory Orbitals are conserved - the number of atomic orb

12、itals combined must equal the number of molecular orbitals formed,1.2.4 Introduction of Molecular Theory,The above only shows the bonding molecular orbital, the other one is antibonding molecular orbital, but it contains no electrons.,1.2.4 Introduction of Molecular Theory,The 1s atomic orbitals can

13、 combine in one of two ways,1.2.4 Introduction of Molecular Theory,- The 1s atomic orbitals combine in a way that enhance each other, similar to two light waves or two sound waves that reinforce each other. It is a sigma bonding molecular orbital 键 - The 1s atomic orbitals can also combine in a way

14、that cancel each other, producing a node between the nuclei. It is a sigma antibonding molecular orbital * 键,1.2.4 Introduction of Molecular Theory,Side-to-side overlapping of in-phase p orbitals produces a bonding pi- molecular orbital 键 Side-to-side overlapping of out-of-phase p orbitals producing

15、 an antibonding pi- molecular orbital * 键,1.3 碳的杂化轨道理论 Hybridization,1.3.1 sp3 Hybridization C 1s22s22p2 - 2s22px12py12pz0 2s12px12py12pz1 2s + 2px2py2pz 4 sp3 hybridization orbitals each orbital has one electron,1.3.1 sp3 Hybridization,to form a tetrahedron carbon (see the structure of methane),1.3

16、.1 sp3 Hybridization,Configuration isomers - enantiomers a chiral carbon - a carbon linked with four different kinds of atoms Conformation isomer - ethane,1.3.2 sp2 Hybridization,C 1s22s22p2 - 2s22px12py12pz0 2s12px12py12pz1 2s + 2px2py + 2pz 3 sp2 hybridization orbitals + 1 2pz each orbital has one

17、 electron,1.3.2 sp2 Hybridization,to form a planer carbon (see the structure of Ethene) another kind of stereo-isomer - Geometric Isomerization - cis, trans,1.3.3 sp Hybridization,to form a liner carbon (see the structure of Ethyne) Optical Activity in Allenes,1.3.4 有机化合物异构现象 Isomerism,1.3.4 有机化合物异构

18、现象 Isomerism,关于碳化合物的异构问题请参阅 -邢其毅“基础有机化学”P166 Isomers Constitutional isomers Stereoisomers Configurational isomers Conformational isomers Optical isomers Geometric isomers Enantiomers Diastereomers,1.4 有机分子的基本骨架和官能团,1.4.1 基本骨架 - 由碳碳键和碳氢键构成 1.4.2 官能团（Functional Groups)： 1.4.2.1 Containing Nitrogen: Am

19、ines: RNH2, R2NH, R3N, （R4N+X-） Imines: -C=NH, -C=NR; Nitrile: RCN (-CN, cyano group ),1.4.2.1 Containing Nitrogen,The structure Features: N: ( 1s2 )2s22p3 sp3, sp2, sp hybridization C-N single, double, triple bond 4 orbitals, but 5 electrons in an atoms there is a lone pair of electrons Hydrogen-Bo

20、nd - electronegativity Polar Covalent Bond - electronegativity,1.4.2.2 Containing Oxygen,Ethers R-O-R Alcohols R-OH Aldehydes, Ketones R(H)C=O, R2 C=O Carboxylic Acids and their Derivatives RCOOH, RCOOR, RCONR2, RCOX,1.4.2.2 Containing Oxygen,The structure Features: O: ( 1s2 )2s22p4 sp3, sp2 hybridi

21、zation C-O single, double bond 4 orbitals, but 6 electrons in an atoms there is two lone pairs of electrons Hydrogen-Bond - electronegativity Polar Covalent Bond - electronegativity,1.4.2.3 Containing halogen,Alkyl Halides +R-X - R+ + X- Structural Features: X: ns2np5 halogen - electronegativity is

22、bigger than carbon Polar Covalent Bond,1.4 有机分子的基本骨架和官能团,以下内容请参阅教材第二十五章结构部分 1.4.2.4 Containing Sulfur 1.4.2.5 Containing Phosphorus 1.4.2.6 Containing Boron 1.4.2.7 Containing Silison,1.5 有机化合物的结构与性质的关系,1.5.1 共价键的结构与性质关系 - Key Part of Organic Chemistry e.g. 1. Hydrocarbons Alkanes, Alkenes, Alkynes

23、and Aromatic CH3CH3, CH2=CH2, CH CH, Substitute Reaction, Addition Reaction, C6H6 - Addition, difficult; Substitution, easy,1.5 有机化合物的结构与性质的关系,eg 2 C=O, C=C addition reaction but mechanism are different eg 3 RH, ROH, RCOOH acidity increase from left to right eg 4 Compounds containing O or N, compari

24、ng with C, have lone pair of electron, so they often work as Lewis base.,作业2： 阅读教材相关部分，从有机化合物的结构出发，简要概括各主要官能团化合物的化学性质（建议列表格对应性质与结构特征） （第六周交）,1.5.2 非共价力与性质的关系,非共价力包括： 氢键 Hydrogen Bond 范德华作用力 （吸引力和斥力） 偶极-偶极作用力等（见下表） 作用于分子间和分子内 影响化合物的物理性质和化学性质 熔点、沸点、溶解性能 酸碱性、反应速度和反应方向,非共价力及其强度,1.5.2 非共价力与性质的关系,氢键的饱和性和方

25、向性 饱和性由于氢原子特别小，而原子A和B比较大，所以A-H中的氢原子只能和一个B原子结合形成氢键；同时，由于负离子之间的相互排斥，另一个电负性大的原子B 就难于再接近氢原子.,1.5.2 非共价力与性质的关系,方向性由于电偶极矩A-H与原子B的相互作用，只有当A-HB在同一直线上时最强；同时，由于原子B一般含有未共用电子对，在可能的范围内氢键的方向和未共用电子对的对称轴一致，这样可使原子B中负电荷分布最多的部分最接近氢原子，这样形成的氢键最稳定。,1.5.2 非共价力与性质的关系,氢键的强弱A、B的电负性越大，氢键越强；B的原子半径越小，氢键越强。（F-HF最强）,1.5.2 非共价力与性质

26、的关系,氢键对分子构象的影响,1.5.2 非共价力与性质的关系,氢键对互变异构平衡的影响,1.5.2 非共价力与性质的关系,氢键对酸性的影响,1.5.2 非共价力与性质的关系,天然化合物中的氢键举例核酸结构中的氢键；蛋白质结构中的氢键,1.5.3 立体结构与性质的关系,1.6 质子酸碱和路易斯酸碱理论,1.6.1 酸碱概念的发展 1663年 （英）Boyle, R. 酸具有酸味，能使蓝色石蕊变红 碱具有苦涩味，能使红色石蕊变蓝 18世纪后期，从物质内在性质认识酸碱 1781年 （法）Lavoisier, A. L. 酸是一类含氧化合物，氧酸素 19世纪初，HCl，HI等被发现 1811年 Davy, D. P. 提出“氢是酸的基本元素”的论点,1.6 质子酸碱和路易斯酸碱理论,1.6.1 酸碱概念的发展 19世纪后期，近代酸碱理论开始形成 A、1889年 Arrhenius, S. A. 水-离子论 20世纪 B、 Franklin, F.C. 溶剂论 C、Bronsted, J. N.-Lowry, T. M. 质子论 D、Lewis, G. N. 电子论 E、Pearson, R. G. 软硬酸碱理论,1.6 质子酸碱和路易斯酸碱理论,1.6.2 Arrihenius 离子论 在水溶液中能电离出氢离子的物质