西北农林科技大学：《有机化学 Organic chemistry》课程教学课件（2012）Chapter 07 Alkyl Halides Nucleophilic Substitution and Elimination

0 花华院 Organic Chemistry,6h Edition L.G.Wade,Jr. Chapter 7 Alkyl Halides:Nucleophilic Substitution and Elimination By Junru Wang Email:wangjr07@163.com

By Junru Wang Email: wangjr07@163.com Chapter 7 Alkyl Halides: Nucleophilic Substitution and Elimination Organic Chemistry, 6 h Edition L. G. Wade, Jr

0环+ Key Notes Nucleophilic Substitution ●SN1 ●SN2 ■Elimination(E1,E2) ■Nucleophilicity .The rate of the SN2 reaction increases with the nucleophilic strength of the incoming nucleophile. OThe rate of the SN1 reaction is unaffected by the nature of the nucleophile ■Leaving group

Key Notes Nucleophilic Substitution SN1 SN2 Elimination（E1，E2） Nucleophilicity The rate of the SN2 reaction increases with the nucleophilic strength of the incoming nucleophile. The rate of the SN1 reaction is unaffected by the nature of the nucleophile Leaving group

0 Content 发牌院。 Preparation and physical properties Nucleophilic substitution Factors affecting SN2 versus SN1 reactions ■Elimination Elimination versus substitution Reactions of alkyl halides Organometallic reactions

Content Preparation and physical properties Nucleophilic substitution Factors affecting SN2 versus SN1 reactions Elimination Elimination versus substitution Reactions of alkyl halides Organometallic reactions

育不6特材车 Classes of Halides 花院 Alkyl:Halogen,X,is directly bonded to sp3 carbon. Vinyl:X is bonded to sp2 carbon of alkene. Aryl:X is bonded to sp2 carbon on benzene ring. Examples: HH H H一C一C一Br H H CI alkyl halide vinyl halide aryl halide

Classes of Halides Alkyl: Halogen, X, is directly bonded to sp3 carbon. Vinyl: X is bonded to sp2 carbon of alkene. Aryl: X is bonded to sp2 carbon on benzene ring. Examples: C H H H C H H Br alkyl halide C C H H H Cl vinyl halide I aryl halide

0礼不水牛大号 Classes of Alkyl Halides Methyl halides:only one C,CH2X Primary:C to which X is bonded has only one C-C bond. Secondary:C to which X is bonded has two C-C bonds. Tertiary:C to which X is bonded has three C-C bonds

Classes of Alkyl Halides Methyl halides: only one C, CH 3 X Primary: C to which X is bonded has only one C-C bond. Secondary: C to which X is bonded has two C-C bonds. Tertiary: C to which X is bonded has three C-C bonds

清我不8米大 Polarity and Reactivity Halogens are more electronegative than C. Carbon-halogen bond is polar,so carbon has partial positive charge. Carbon can be attacked by a nucleophile. Halogen can leave with the electron pair. H+ 6+6- HC一C】 H chloromethane EPM of chloromethane Copyright2005 Pearson Prentce Hall,Inc

Polarity and Reactivity Halogens are more electronegative than C. Carbon-halogen bond is polar, so carbon has partial positive charge. Carbon can be attacked by a nucleophile. Halogen can leave with the electron pair

0环行 Uses of Alkyl Halides" Solvents-degreasers and dry cleaning fluid Reagents for synthesis of other compounds Anesthetic:Halothane is CFCHCIBr ●CHCl3 used originally(toxic and carcinogenic)麻醉剂 >In 1847,the Edinburgh obstetrician James Young Simpson first used chloroform for general anesthesia during childbirth Freons,chlorofluorocarbons or CFC's Freon 12,CF2Cl2,now replaced with Freon 22, CF,CHCI,not as harmful to ozone layer. Pesticides -DDT banned in U.S. extremely toxic to insects but not as toxic to mammals

Uses of Alkyl Halides Solvents - degreasers and dry cleaning fluid Reagents for synthesis of other compounds Anesthetic: Halothane is CF 3CHClBr CHCl 3 used originally (toxic and carcinogenic)麻醉剂 In 1847, the Edinburgh obstetrician James Young Simpson first used chloroform for general anesthesia during childbirth Freons, chlorofluorocarbons or CFC’s Freon 12, CF 2Cl 2, now replaced with Freon 22, CF 2CHCl, not as harmful to ozone layer. Pesticides - DDT banned in U.S. extremely toxic to insects but not as toxic to mammals

0环4+大 Uses of Alkyl Halides" 杀虫剂、杀灭蚊子（疟疾) DDT1939年后广泛使用（残留高) Srilanka ●1934-1935150万(8万died) ●1963：仅15例 ●1968-1969第二季度60万例 1972:环境保护组织(EPA) 废除 ■冷却液和喷气燃料推进剂

Uses of Alkyl Halides 杀虫剂、杀灭蚊子（疟疾） DDT 1939年后广泛使用（残留高） Srilanka : 1934-1935 150万（ 8 万 died ） 1963: 仅15 例 1968-1969第二季度60万例 1972：环境保护组织（EPA）废除 冷却液和喷气燃料推进剂

0环行 B.P Densities 院。 Greater intermolecular forces,higher b.p. .Dipole-dipole attractions not significantly different for different halides London forces greater for larger atoms Greater mass,higher b.p. Spherical shape decreases b.p. (CH3)3CBr CH3(CH2)3Br 73C 102°C ■Densities .Alkyl fluorides and chlorides less dense than water. .Alkyl dichlorides,bromides,and iodides more dense than water

B.P & Densities Greater intermolecular forces, higher b.p. Dipole-dipole attractions not significantly different for different halides London forces greater for larger atoms Greater mass, higher b.p. Spherical shape decreases b.p. (CH 3 ) 3CBr CH 3(CH 2 ) 3Br 73 C 102  C Densities •Alkyl fluorides and chlorides less dense than water. •Alkyl dichlorides, bromides, and iodides more dense than water

Sec 1 PREPARATION AND PHYSICAL PROPERTIES ■PREPARATION .Halogenation(Allylic Halogenation) ●Vith HX ●From alcohol ●Diazonium coupling(for aryl halide only） ■Use

Sec 1 PREPARATION AND PHYSICAL PROPERTIES PREPARATION Halogenation(Allylic Halogenation) With HX From alcohol Diazonium coupling (for aryl halide only) Use