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第三章　 单烯烃

第三章　 单烯烃. 洛阳师院化学系有机化学教研室. 官能团： ，通式： C n H 2n . 第一节 烯烃的结构 乙烯的键参数. C=C 键能610 kJ/mol. p -Bonding (Bonding molecular orbital). 乙烯分子的形成. 乙烯模型. 烯烃的反应. 第二节 烯烃的同分异构和命名. 一、烯烃的同分异构 烯烃的异构包括碳干异构、位置异构、顺反异构。 例：丁烯有5种同分异构体：. 顺（ cis）： 两个双键上的氢原子处于双键的同一侧；反（ trans）：～～～ 处于异侧。.

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第三章　 单烯烃

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  1. 第三章　 单烯烃 洛阳师院化学系有机化学教研室

  2. 官能团： ，通式：CnH2n. 第一节 烯烃的结构 乙烯的键参数 C=C 键能610kJ/mol

  3. p-Bonding(Bonding molecular orbital)

  4. 乙烯分子的形成 乙烯模型 烯烃的反应

  5. 第二节 烯烃的同分异构和命名 • 一、烯烃的同分异构 烯烃的异构包括碳干异构、位置异构、顺反异构。 例：丁烯有5种同分异构体：

  6. 顺（cis）：两个双键上的氢原子处于双键的同一侧；反（trans）：～～～处于异侧。顺（cis）：两个双键上的氢原子处于双键的同一侧；反（trans）：～～～处于异侧。

  7. 二、烯烃的命名 • 1. 选择含双键最长的碳链作为主链（母体），根据主链碳原子数命名为某烯。 • 2. 从靠近双键最近的一端开始编号。 • 3. 命名时双键的位次必须表明，以双键碳原子中编号小的表示。 5,5-二甲基-1-己烯

  8. Ethene Propene “Ethylene” “Propylene” 1-Butene 2-Butene

  9. 2-Methyl-2-butene

  10. 6-Methyl-2-heptene

  11. 6-Methyl-2-heptene

  12. 烯基 • Ethyl CH2=CH- Vinyl • 1-Propenyl • 2-Butenyl • 2-Pentenyl Allyl Isopropenyl(for 1-methylvinyl)

  13. E-Z Nomenclature

  14. E-Z Nomenclature Rules • SEQUENCE RULE 1: If the four atoms directly attached to the double bond are all different, priority depends on atomic number, with the atom of higher atomic number receiving the higher priority. • COROLLARY: If two atoms are isotopes of the same element, the heavier isotope receives the higher priority.

  15. E-Z Nomenclature Rules • SEQUENCE RULE 2: If the relative priority of two groups cannot be decided by Rule 1, it shall be determined by a similar comparison of the next atoms in the groups (and so on, if necessary), working outward in ranks from the double bond.

  16. E-Z Nomenclature Rules • To complete the IUPAC name of a particular isomer, enclose the (E) or (Z) symbol in parentheses and place it at the front of the entire name of the compound. Separate the (E) or (Z) symbol from the rest of the name with a hyphen.

  17. Examples Question: (CH3)3C-与 -CH2Cl哪个为优先基团？

  18. trans-6-Methyl-3-propyl-2-octene (Don’t worry about “trans” until Chapter 4)

  19. Intention 1. Z、E和顺（Cis）、反（Trans）并不总是一一对应的。

  20. 第三节 烯烃的化学性质 • 典型反应：加成反应－－在反应中，  键断开，两个不饱和原子和其它原子或原子团结合，形成两个键，这种反应称为加成反应。 Remember it!

  21. Addition Reactions

  22. 一、催化氢化 催化剂异相催化剂：铂黑、钯粉、RaneyNi; Fe、Cr、Cu.均相催化剂：主要为过渡金 属配合物 乙烯加氢

  23. Hydrogenation of Alkenes Also PtO2 -- sometimes Ru, Rh, or Re

  24. . . . H H H Hydrogen Adsorbed on Catalyst Surface . . . H H H Pt Pt Pt Pt Pt Pt Pt Pt Pt Pt Pt HYDROGEN ADSORBS ON THE SURFACE OF THE CATALYST . n H2 + Pt Pt(H )2n finely-divided particles dispersed in solution

  25. H H . . H . . H . H H . H . H H MECHANISM OF HYDROGENATION CATALYST

  26. . . . . H H H . . H . H H . H . H H MECHANISM OF HYDROGENATION HYDROGEN ADSORBS

  27. R R R R . . . . . . H H H . . H . H H . H . H H MECHANISM OF HYDROGENATION ALKENE APPROACHES

  28. R R R R . . . . . . H H H . . H . H H . H . H H MECHANISM OF HYDROGENATION ALKENE PICKS UP TWO HYDROGENS

  29. . . H H . . H . . H . H H . H . H H MECHANISM OF HYDROGENATION R R R R ALKANE IS FORMED . .

  30. 氢化热：1mol不饱和化合物氢化时放出的热量。氢化热：1mol不饱和化合物氢化时放出的热量。 氢化热的大小反应烯烃的相对稳定性。 双键碳原子上的烷基越多，烯烃越稳定。 R2C=CR2>R2C=CHR>RCH=CHR> RCH=CH2>CH2=CH2. 2-甲基丙烯>反-2-丁烯>顺-2-丁烯>1-丁烯。

  31. Alkene Stability

  32. 二、亲电加成 Electrophilic Addition to a Double Bond 亲电试剂（E＋）：凡缺电子物种，如正离子等。

  33. 1. 与酸的加成 强酸如硫酸、氢卤酸可以直接作用；弱有机酸（如乙酸）、醇、水等要在强酸催化下进行。 1）与卤化氢加成 （Addition of Hydrogen Halides）

  34. 卤化氢对烯烃加成的活性次序：HI>HBr>HCl Markovnikov Addition to an Alkene

  35. Markovnikov Addition to an Alkene

  36. Markovnikov Rule • In the ionic addition of an acid to the carbon-carbon double bond of an alkene, the hydrogen of the acid attaches itself to the carbon atom which already holds the greater number of hydrogens. • “Them that has, gets!” • “The richer get richer!” (V. W. Markovnikov -- 1838 - 1904)

  37. REGIOSELECTIVE REACTION 区位选择性反应 C H C H C H 3 3 3 HCl C H C C H C H C C H + C H C H C H 3 2 3 3 3 2 C l C l major minor one of the possible products is formed in larger amounts than the other one REGIOSPECIFIC Compare only one of the possible products is formed (100%).

  38. MARKOVNIKOV RULE When adding HX to a double bond the hydrogen of HX goes to the carbon which already has the most hydrogens C H C H 3 2 C l + HCl ..... conversely, the anion X adds to the most highly substituted carbon ( the carbon with most alkyl groups attached).

  39. KARASCH效应（过氧化物效应 在过氧化物存在下，氢溴酸与不对称烯烃加成时，反应取向是Anti-Markovnikov rule. Reading Assignment: 本章第七节

  40. 2）与硫酸加成 与不对称烯烃加成同样遵循Markovnikov rule. 用上法制备醇叫间接水合，设备腐蚀严重。

  41. Addition of Sulfuric Acid to an Alkene

  42. Addition of Water to an Alkene

  43. 直接水合： 2. 与卤素加成 卤素对烯烃加成的活性次序：F2>Cl2>Br2>I2(不反应） Br/CCl4溶液用来检验烯烃 ICl 、 IBr次卤酸（X2+H2O)与不对称烯烃加成的主要产物为何？

  44. Halohydrin Formation 卤代醇的形成 HOBr

  45. 3. 与乙硼烷加成(硼氢化反应：由B－H键对烯烃双键进行的加成反应）由C. H. Brown建立

  46. 绝大多数烯烃与二硼烷的加成产物是三烷基硼，少数立体障碍大的烯烃则停留在一烷基硼或二烷基硼阶段。绝大多数烯烃与二硼烷的加成产物是三烷基硼，少数立体障碍大的烯烃则停留在一烷基硼或二烷基硼阶段。

  47. Sia2BH，thBH2(HBH2）, 9-BBN

  48. 特点： 特点：1.氢加到含氢较少的双键碳原子上；2.顺式加成，选择性好；3.产率高；4.反应条件温和。 合成应用：

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