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By junru wang

Organic chemistry 生物学科 有机化学教学多媒体课件 2006.02. By junru wang. 作业 :. P151: 1 : (2,3,4,6) 3: (3,4) 4: (3,4). 第 4 章 立 体 化 学. Stereochemistry. 胰岛素. 第四章 Stereochemistry 重点讲授内容. 一、分子手性与旋光性 Molecular Chirality:Enantiomers 二、对称性、手性、手性碳与构型标记 三、不含手性碳的旋光活性分子 四、光活性物质的物性与旋光性的测定 五、反应中的立体化学

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By junru wang

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  1. Organic chemistry 生物学科 有机化学教学多媒体课件 2006.02 By junru wang

  2. 作业: • P151: • 1: (2,3,4,6) • 3: (3,4) • 4: (3,4)

  3. 第4章 立 体 化 学 Stereochemistry

  4. 胰岛素

  5. 第四章 Stereochemistry重点讲授内容 • 一、分子手性与旋光性 Molecular Chirality:Enantiomers • 二、对称性、手性、手性碳与构型标记 • 三、不含手性碳的旋光活性分子 • 四、光活性物质的物性与旋光性的测定 • 五、反应中的立体化学 • 六、光活性混合物的拆分方法

  6. 第一节 分子手性与旋光性Molecular Chirality: Enantiomers

  7. 第一节 分子手性与旋光性Molecular Chirality: Enantiomers

  8. The ancient Egyptians had less care for the chirality of hands Pharaohs, with two left hands or two right hands—they just didn’t seem to notice.

  9. Chirality A molecule is chiralif its two mirror image forms are notsuperposable upon one another. A molecule is achiral if its two mirror image forms are superposable.

  10. Bromochlorofluoromethane is chiral It cannot be superposed point for point on its mirror image. Cl Br H F

  11. Bromochlorofluoromethane is chiral To show nonsuperposability, rotate this model 180° around a vertical axis. Cl Cl Br Br H H F F

  12. Bromochlorofluoromethane is chiral Cl Br Cl Br H H F F

  13. Another look

  14. Enantiomers are enantiomers with respect to each other nonsuperposable mirror images are called enantiomers and

  15. 碳架异构 位置异构 构造异构 官能团异构 （互变异构） 同分异构 构象异构 顺反异构 立体异构 构型异构 对映异构 旋光异构 对映异构：分子式、构造式相同、构型互呈镜像对映关系的立体异构现象

  16. Chlorodifluoromethaneis achiral

  17. Chlorodifluoromethaneis achiral The two structures are mirror images, but are not enantiomers, because they can be superposed on each other.

  18. w x y C z The Stereogenic Center a carbon atom with fourdifferent groups attached to it also called: chiral centerasymmetric centerstereocenter

  19. 第二节 对称性、手性、手性碳与构型标记 • 对称性与手性 • 手性碳与分子手性 • 手性、对称性与旋光性 • 构型标记 • 绝对构型 • 相对构型

  20. 一、旋光性与分子结构的关系 • 凡是可具有结构不对称性（无反映对称性）的分子都具有旋光性；最常见的旋光活性物质是含有手性碳的化合物。 • 对称因素：对称面（）；对称中心(i) • 对称性、不对称性与手性: 凡是具有反映对称性的分子称为非手性分子 凡是没有反映对称性的分子称为手性分子 • 不对称性：找不到任何一个对称因素的分子 • 手性是不对称性之一种 • 反映对称性———对称分子———无旋光性

  21. 一、旋光性与分子结构的关系 • 对称性与手性: 有对称性的分子一定是非手性分子 有手性的分子一定具有非反映应对称性 • 手性碳与手性分子二者关系 有手性碳的分子不一定就是手性分子 手性分子并不一定就含有手性碳 只有一个手性碳的分子一定就是手性分子

  22. 一、旋光性与分子结构的关系 • 手性碳与手性分子二者关系 手性分子并不一定就含有手性碳 右手螺旋 左手螺旋

  23. 一、旋光性与分子结构的关系 • 手性、对称性与旋光性 （1）有反应对称性的分子：物象重合，不具有旋光性，是非手性分子 （2）无对称性的分子：物象不重合，有旋光性，是手性分子 • 构型与旋光性 分子结构的不对称性导致，物象不重合；二者主要差异在于构型不同；

  24. 对称因素 手性(chirality)：物质的分子与其镜像不能重合的性质，是产生旋光性的充分和必要条件。 1、对称面(Mirror) 反映对称性: Sn,n1; S1= ; S2=i

  25. Plane of symmetry A plane of symmetry bisects a molecule into two mirror image halves. Chlorodifluoromethane has a plane of symmetry.

  26. Plane of symmetry A plane of symmetry bisects a molecule into two mirror image halves.1-Bromo-1-chloro-2-fluoroethene has a planeof symmetry.

  27. 2、对称中心 对称中心

  28. Center of symmetry A point in the center of themolecule is a center of symmetry if a line drawn from it to some element, when extended an equal distance in the opposite direction, encounters an identical element.

  29. Center of symmetry A point in the center of themolecule is a center of symmetry if a line drawn from it to any element, when extended an equal distance in the opposite direction, encounters an identical element.

  30. 对称中心 反映对称性: Sn,n1; S1= ; S2=i

  31. 3、对称轴 对称轴

  32. 4、更替对称轴

  33. C Chirality and stereogenic centers A molecule with a single stereogenic center is chiral. Bromochlorofluoromethane is an example. H F Cl Br

  34. C Chirality and stereogenic centers A molecule with a single stereogenic center is chiral. 2-Butanol is another example. H CH3 CH2CH3 OH

  35. CH3 CH2CH2CH2CH3 CH3CH2CH2 C CH2CH3 Examples of molecules with 1 stereogenic center a chiral alkane

  36. OH Examples of molecules with 1 stereogenic center Linalool, a naturally occurring chiral alcohol

  37. H2C CHCH3 O Examples of molecules with 1 stereogenic center attached to the stereogenic center are: —H —CH3 —OCH2 —CH2O 1,2-Epoxypropane: a stereogenic center can be part of a ring

  38. CH3 H C CH2 CH3 Examples of molecules with 1 stereogenic center attached to thestereogenic center are: —H —CH2CH2 —CH2CH= —C= Limonene: a stereogenic center can be part of a ring

  39. H CH3 D C T Examples of molecules with 1 stereogenic center Chiral as a result of isotopic substitution

  40. 二、构型标记Relative and Absolute Configuration • 相对构型 • 绝对构型

  41. Configuration • 相对构型 • Relative configurationcompares the arrangement of atoms in space of one compound with those of another. • until the 1950s, all configurations were relative • 绝对构型 • Absolute configuration is the precise arrangement of atoms in space. • now we can determine the absolute configuration of almost any compound

  42. 1、相对构型标记D/L CHO CHO （+）－甘油醛 （-）－甘油醛 D L D －（+）－甘油醛 L－（-）－甘油醛 常用来确定糖、氨基酸等构型 H OH HO H CH2OH CH2OH

  43. D -（+）- 甘油醛 L -（+）- 甘油醛 D-（+）-甘油醛 D-（-）-甘油酸 D-（-）-乳酸 相对构型(Relative Conformation) 化学关联法：

  44. R -（+）- 甘油醛 S -（+）- 甘油醛 2、绝对构型的标记 • 1970 IUPAC R/S 标记任何一个手性碳(或手性分子) • 明确与手性碳相连的4个不同基团的优先次序 • 用手模型法或透视法判断其构型 Which is which? E. Fisher 1891; 1954 x-ray证实

  45. 绝对构型(Absolute Conformation) IUPAC(1970) R、S构型系统命名法： a>b>c>d

  46. 1 1 4 3 3 4 2 2 Example 2.1 含一个手性碳的化合物 Order of decreasing rank:4 > 3 > 2 > 1

  47. 1 1 4 3 3 4 2 2 Example Order of decreasing rank:4>3> 2 anticlockwise clockwise R S

  48. H H CH2CH3 CH3CH2 C HO C OH CH3 H3C Enantiomers of 2-butanol (S)-2-Butanol (R)-2-Butanol

  49. H3C H R H H Stereogenic center in a ring —CH2C=C > —CH2CH2 > —CH3 > —H

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