华南师范大学：《有机化学》课程PPT教学课件（双语版）Chapter 7 Radical reactions

7.1 Introduction Homolysis a B A·+B Production of radical heat R—0--0—R一 2R—0● Dialkyl peroxide Alkoxyl radical 二烷基过氧化物 烷氧基自由基 homolysis 2X heat or light

7.1 Introduction A B Homolysis A + B Production of Radical; R O O R heat 2R O Dialkyl peroxide 二 烷 基 过 氧 化 物 Alkoxyl radical 烷 氧 基 自 由 基 X X homolysis heat or light 2 X

Reactions of radicals General reaction homolysis X-:-X 2X· heat or light H一:-cH 3 HX+·CH3 CH3 X-I-X CHX +X

Reactions of Radicals General reaction X X homolysis heat or light 2 X X + H CH3 HX + CH3 CH3 + X X CH3 X + X

7.2 Homolytic bond dissociation energies 7. 2A Homolytic bond dissociation energies and heats of reaction 7.2B Homolytic bond dissociation energies and the relative stabilities of radicals

7.2 Homolytic bond dissociation energies 7.2A Homolytic bond dissociation energies and heats of reaction 7.2B Homolytic bond dissociation energies and the relative stabilities of radicals

7.2B Homolytic bond dissociation energies and the relative stabilities of radicals Homolytic bond dissociation energies also provide us with a convenient way to estimate the relative stabilities of radicals

7.2B Homolytic bond dissociation energies and the relative stabilities of radicals Homolytic bond dissociation energies also provide us with a convenient way to estimate the relative stabilities of radicals

Relative stabilities of radicals CH3CH2CH2-—H CErCI ch H △FP=+94.5km2三 AH =+98 kcal mol- Propyl radical CH3CHCH3 HrCHCh3 Ho Isopropyl radical CH3 2 radical CH. 3 CH3CCH3 CHCCH3 +h. △Ho=+91 kcal mol H tert-Butyl radical 3° radical

Relative stabilities of radicals CH3 CH2 CH2 H CH3 CH2 CH2 + H Propyl radical 1 o radical H o = +98 kcal mol -1 CH3 CHCH3 H CH3 CHCH3 + H H o = +94.5 kcal mol -1 Isopropyl radical 2 o radical CH3 CCH3 CH3 H H o = +91 kcal mol -1 CHCCH3 CH3 + H tert-Butyl radical 3 o radical

Relative stabilities c CHCCH CH3CHCH3 CH3CH2CH2· ropyl radical P tert-Butyl radical Isopropyl radical 3° radical radica 2 radical Tertiary radical> Secondary radical>Primary radical Methyl radical 叔自由基 仲自由基 伯自由基 甲基自由基 radical)2° radical>1° radical>:C

Relative stabilities CH3 CH2 CH2 Propyl radical 1 o radical CH3 CHCH3 Isopropyl radical 2 o radical CHCCH3 CH3 tert-Butyl radical 3 o radical Tertiary radical 叔 自 由 基 Secondary radical 仲自由基 Primary radical 伯自由基 Methyl radical 甲基自由基 3 o radical 2 o radical 1 o radical CH3

7.3 The reactions of alkanes with halogens Methane, ethane, and other alkanes react with the first three members of the halogen family: fluorine, chlorine, and bromine, alkanes do not react appreciably with iodine. With methane the reaction produces a mixture of halomethanes and a hydrogen halide

7.3 The reactions of alkanes with halogens Methane, ethane, and other alkanes react with the first three members of the halogen family: fluorine, chlorine, and bromine. Alkanes do not react appreciably with iodine. With methane the reaction produces a mixture of halomethanes and a hydrogen halide

Ha| ogenation reactions(卤化反应) heat CH4 X2- CH3x CH2x2+ CHX3 CX4 HX or light XF, CI halomethane dihalomethane trihalomethane tetrahalomethane or br The reaction of an alkane with a halogen is called halogenation. In these reactions a halogen atom replaces one or more of the hydrogen atoms of the alkane. Reactions of this type, in which one atom or group replaces another. are called substituion reactions

Halogenation reactions (卤化反应） CH4 + X2 heat or light CH3X + CH2X2 + CHX3 + CX4 + HX X=F halomethane dihalomethane trihalomethane tetrahalomethane , Cl, or Br The reaction of an alkane with a halogen is called halogenation. In these reactions a halogen atom replaces one or more of the hydrogen atoms of the alkane. Reactions of this type, in which one atom or group replaces another, are called substituion reactions

7.3A Halogenation reactions (multiple substitution reactions) heat CH Cl CH3Cl t HCl or light Chloromethane(氯甲烷) CH3Cl Cl CHCh+ HCI DiChloromethane(二氯甲烷) CH2Cl2 Ch- CHCl3+ HCI Trichloromethane(三氯甲烷)(氯仿) CHCl3+Cl2—>CCl4+HCl Tetra chloromethane四氯化碳)

7.3A Halogenation reactions (multiple substitution reactions) CH4 + Cl 2 heat or light CH3Cl + HCl CH3Cl + Cl 2 CH2Cl 2 + HCl CH2Cl 2 + Cl 2 CHCl 3 + HCl CHCl 3 + Cl 2 CCl 4 + HCl Chloromethane (氯 甲 烷 ） DiChloromethane (二氯 甲 烷 ） TriChloromethane (三 氯 甲 烷 ） （ 氯 仿 ） TetraChloromethane (四 氯 化 碳 ）

heat CH3CH3 Cl CHrCHCI HCl or light Chloroethane(氯乙烷) CH3 CHCI2 HCI Cl2 1.1-Dichloroethane CH3 CH,CI CICH2CH2CI HCI 1.2-Dichloroethane

CH3 CH3 + Cl 2 heat or light CH3 CH2 Cl + HCl Chloroethane (氯 乙 烷 ） CH3 CH2 Cl Cl 2 CH3 CHCl 2 + HCl 1,1-Dichloroethane ClCH2 CH2 Cl + HCl 1,2-Dichloroethane