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）第六章 离子反应 —卤代烃的亲核取代和消除反应（6.10-6.14）The Reaction of tert-Butyl

ORGANIC CHEMISTRY Chapter 6 6.10 The Reaction of tert-Butyl Chloride with Hydroxide lon: An S1 Reaction Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.10 The Reaction of tert-Butyl Chloride with Hydroxide Ion: An SN1 Reaction

ORGANIC CHEMISTRY Chapter 6 acetone (CH3)3C-CI OH H,O(CH2)2C-OH Cl Rate∝[(CH3)3CC Rate=k[(ch3)3CCl First order overal(一级反应) The reaction is a unimolecular nucleophilic substitution(单分子亲核取代反应) S reaction Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 (CH3)3C Cl + OH acetone H2O (CH3)3C OH + Cl Rate ∝ [(CH3)3CCl] Rate = k [(CH3)3CCl] First order overall (一级反应) The reaction is a unimolecular nucleophilic substitution（单分子亲核取代反应） SN1 reaction

ORGANIC CHEMISTRY Chapter 6 6. 10A Multistep Reactions and the rate- Determining Step Consider a multistep reaction such as the following Step 1 Reactant、Slow intermediate 1 Rate=k,reactant fast Step 2 intermediate 1-+ intermediate 2 Rate=k,intermediate 1] Step 3 intermediate 2+ product Rate=k intermediate 2 k,<< k, or k Step 1 is the rate-limiting step or the rate determining step Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.10A Multistep Reactions and the Rate￾Determining Step Consider a multistep reaction such as the following: slow Rate = k1 Step 1 Reactant intermediate 1 [reactant] fast Rate = k2 Step 2 intermediate 1 intermediate 2 [intermediate 1] Step 3 intermediate 2 fast Rate = k3 product [intermediate 2] k1 << k2 or k3 Step 1 is the rate-limiting step or the rate determining step

ORGANIC CHEMISTRY Chapter 6 6.11 A Mechanism for the SN Reaction Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.11 A Mechanism for the SN1 Reaction

ORGANIC CHEMISTRY Chapter 6 SIOW Step 1(cH3)3c--cI ( CH3)3C + Cl A carbocation intermediate fast Step 2(CH3)3C +OH =(CH3)3C-OH Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 (CH3)3C Cl slow (CH3)3C + Cl A carbocation intermediate Step 1 (CH3)3C + OH fast (CH3) Step 2 3C OH

ORGANIC CHEMISTRY Chapter 6 6.12 Carbocations Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.12 Carbocations

ORGANIC CHEMISTRY Chapter 6 6. 12a The Structure of carbocation o The structure of carbocation is trigonal planar g The center carbon atom in a carbocation is electron deficient o The p orbital contains no electrons H3CILC-CH3 HC Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.12A The Structure of Carbocation The structure of carbocation is trigonal planar. The center carbon atom in a carbocation is electron deficient. The p orbital contains no electrons. C CH3 H3C H3C

ORGANIC CHEMISTRY Chapter 6 6. 12B The relative Stabilities of Carbocations ( CH3)3C +>(CH3)2 CH >CH3 CH2>CH CH=CH-CH 3°>2°>1°> methyl o The relative stabilities of carbocations are related to the number of alkyl groups attached to the positively charged trivalent carbon atom o a charged system is stabilized when the charge is dispersed or localize d The delocalization of charge and the order of stability of the carbocations parallel the number of attached methyl groups Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.12B The Relative Stabilities of Carbocations CH2 CH CH2 > > > (CH3)3C CH3CH2 CH3 (CH3)2CH 3° >2° >1° >methyl The relative stabilities of carbocations are related to the number of alkyl groups attached to the positively charged trivalent carbon atom. A charged system is stabilized when the charge is dispersed or delocalized. The delocalization of charge and the order of stability of the carbocations parallel the number of attached methyl groups

ORGANIC CHEMISTRY Chapter 6 6.13 The Stereochemistry of SN1 Reaction Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 6.13 The Stereochemistry of SN1 Reaction

ORGANIC CHEMISTRY Chapter 6 CH CH HrC HO-C →(C◎ C-OH HO OH H3C cH3 H2C CH CH

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 6 C CH3 H3C CH3 OH C H3C H3C CH3 OH C CH3 CH3 CH3 HO HO