厦门大学化学化工学院：《有机化学》课程教学资源（课件讲稿，双语版）第四章 卤代烃 4.4 亲核取代的反应机理 Mechanisms for Nucleophilic Substitution Reactions 4.5.1-4.5.3

44亲核取代的反应机理 Mechanisms for Nucleophilic Substitution Reactions

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 4.4 亲核取代的反应机理 Mechanisms for Nucleophilic Substitution Reactions

Kinetics of Nucleophilic Substitution 9. the exact rate at which a starting material reacts to give product is called the reaction rate and can often be measured In all chemical reactions there is a direct relationship between reaction rate and reagent concentrations When we measure this relationship We measure the kinetic of the reaction

Organic Chemistry Organic Chemistry Xiamen Xiamen University University Kinetics of Nucleophilic Substitution „ The exact rate at which a starting material reacts to give product is called the reaction rate and can often be measured. „ In all chemical reactions, there is a direct relationship between reaction rate and reagent concentrations. When we measure this relationship, we measure the kinetic of the reaction

R—X+Nu RNu +X Nucleophilic substitution RBr+ Naoh R一OH+NaBr CH3 Br OH ChoH + Br V∝[CH3Br[OH]二级反应 (CH3)3 CBr OH (CH3)3 COH Br Vc[(CH3)CBr]一级反应

Organic Chemistry Organic Chemistry Xiamen Xiamen University University R X + Nu R Nu + X N u c l e o p hilic sub stitu tio n R Br + NaOH R OH + NaBr CH 3Br + OH CH 3OH + Br V [C H 3 Br] [O H - ] (C H 3 ) 3CBr + OH (C H 3 ) 3COH + Br V [(C H 3 ) 3CBr ] 一级反应 二级反应

Two important pieces of information have been obtained about the nature of nucleophilic substitution reactions on E primary and secondary alkyl halides and tosy lates: a These reactions always occur with inversion of stereochemistry at the stereogenic carbon center a These reactions show second-order kinetics and follow the rate law: Rate= k [:

Organic Chemistry Organic Chemistry Xiamen Xiamen University University Two important pieces of information have been obtained about the nature of nucleophilic substitution reactions on primary and secondary alkyl halides and tosylates: „ These reactions always occur with inversion of stereochemistry at the stereogenic carbon center. „ These reactions show second-order kinetics and follow the rate law: Rate = k [RX][Nu: - ]

441双分子亲核取代反应(SN2) substitution, nucleophilIC bimolecular OH l C-Br HO----C----Br H HO-CWUH t Br Walden invertion

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 4.4.1 双分子亲核取代反应(S N2) substitution, nucleophilic, bimolecular 4.4.1 双分子亲核取代反应(S N2) substitution, nucleophilic, bimolecular OH H C Br H H H C Br H H HO H HO C H H + Br W a l d e n in v ertio n

Ho--C--Br H H HO一C: Ch2 Br +Oh 反应进程

Organic Chemistry Organic Chemistry Xiamen Xiamen University University CH 3Br + O H H C Br H H HO H HO C H H 反应进程 E

CH CH on+慢 HO C Br CH3 CH, HCH CH3 (R)-2-Bromobutane CH 快 3 HO—Cmn H t Br 23 (S)-2-Butanol 构型翻转

Organic Chemistry Organic Chemistry Xiamen Xiamen University University OH CH 3 C Br H CH 3CH 2 CH 3 HO C H CH 2CH 3 + + Br CH 3 C Br H CH 2CH 3 HO (R)-2-Bro m o b utane (S)-2-Butano l 慢 快 构型翻转

442单分子亲核取代反应(SN1) substitution, nucleophilic unimolecular (CH3)3C-Br (CH 3)3C+OH 快 (CH33C--OH

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 4.4.2 单分子亲核取代反应(S N1) substitution, nucleophilic, unimolecular 4.4.2 单分子亲核取代反应(S N1) substitution, nucleophilic, unimolecular (C H 3 ) 3 C Br (C H 3 ) 3 C (C H 3 ) 3 C OH 慢 OH 快

△G ①D Reaction progress ⑨D (a)

Organic Chemistry Organic Chemistry Xiamen Xiamen University University

△G ①D Reaction progress ⑨D

Organic Chemistry Organic Chemistry Xiamen Xiamen University University