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）第十章 自由基反应（10.1-10.2）概述

Chapter 10 Radical Reactions 自由基反应

Chapter 10 Radical Reactions 自由基反应

ORGANIC CHEMISTRY Chapter 10 10.1 Int troduction Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 10.1 Introduction

ORGANIC CHEMISTRY Chapter 10 Homolysis a-B -A.+B Radicals or free radicals Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 Homolysis A B A B + Radicals or free radicals

ORGANIC CHEMISTRY Chapter 10 10.1A Production of radicals heat R-00-R 2R-0。 homolysis X-X heat or lght X. Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 10.1A Production of Radicals R O O R heat 2 R O X X homolysis heat or light 2 X

ORGANIC CHEMISTRY Chapter 10 10.1B Reactions of radicals X·+H一R X一H+R Alkane Alkyl radical Cl·+H-CH CI-H CH3 Methane Methyl radical Br Br°+C=C Alkene New radical Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 10.1B Reactions of Radicals X + H R X H + R Alkane Alkyl radical Cl + H CH3 Cl H + CH3 Methane Methyl radical Br + C C C C Br Alkene New radical

ORGANIC CHEMISTRY Chapter 10 10.2 Homolysis Bond Dissociation Energies Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 10.2 Homolysis Bond Dissociation Energies

ORGANIC CHEMISTRY Chapter 10 H·+H。—一 H-H△H°=435 kJ mol Cl+Cl·-Cl-Cl△H°=243 kJ mol Bond formation is an exothermic process H-H—+H°+H△H°=+435 kJ mol1 Cl-C|-Cl+C1°△H°=+243 kJ mol1 Homolytic bond dissociation energies Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 Cl + Cl H + H H H Cl Cl ∆H° = 435 kJ mol-1 ∆H° = 243 kJ mol-1 Bond formation is an exothermic process Cl + Cl H H H + H Cl Cl ∆H° = +435 kJ mol-1 ∆H° = +243 kJ mol-1 Homolytic bond dissociation energies

ORGANIC CHEMISTRY Chapter 10 10.2A Homolytic Bond Dissociation Energies and Heats of reaction H-H+Cl-C1—-2H-Cl DH(kJ/mol) 435 243 431×2 +678 kJ/mol is required 862 kJ/mol is evolved for bond cleavage in bond formation △H°=(862+678)=184(kJ/mo) The reaction is exothermic Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 10.2A Homolytic Bond Dissociation Energies and Heats of Reaction H H + Cl Cl 2 H Cl DH°(kJ /mol) 435 243 431× 2 + 678 kJ/mol is required for bond cleavage. −862 kJ/mol is evolved in bond formation. ∆H° = ( 862 + 678) = 184 (kJ/mol) The reaction is exothermic

ORGANIC CHEMISTRY Chapter 10 10.2B Homolytic Bond dissociation Energies and the relative stabilities of Radicals CH3CH2CH2H→CH3CH2CH2+H·△H°=+410kJ/mo Ch2CHCH CH3CHCH3+H△H°=+395 kJ/mol H CH CH CH3 CCH2 CH3 chCH,+H. AH=+381 kJ/mol H CH CH3 CH3CCH2CH2-H—CH3CCH2CH2+H△H=+410 kJ/mol H H Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 10 10.2B Homolytic Bond Dissociation Energies and the relative Stabilities of Radicals CH3CH2CH2 H CH3CHCH3 H CH3CCH2CH3 H CH3 CH3CCH2CH2 H CH3 H CH3CH2CH2 H CH3CHCH3 + + H CH3CCH2CH3 CH3 + H CH3CCH2CH2 H CH3 + H ∆H° = + 410 kJ/mol ∆H° = + 395 kJ/mol ∆H° = + 381 kJ/mol ∆H° = + 410 kJ/mol