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）Chapter 3 An Introduction to Organic Reactions：Acids and Bases（3.1）Reactions and Their Mechanisms

Chapter 3 An Introducton to Organic ons Esids an

Chapter 3 An Introduction to Organic Reactions: Acids and Bases

ORGANIC CHEMISTRY Chapter 3 3.1 Reactions and their mechanisms Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 3.1 Reactions and Their Mechanisms

ORGANIC CHEMISTRY Chapter 3 What kinds of reactions occur 0 reactions occur Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 What kinds of reactions occur ? How reactions occur ?

ORGANIC CHEMISTRY Chapter 3 Substitutions(取代) o Substitution reactions occur when two reactants exchange parts to give two new products o In a substitution, one replaces another A=B+C-D→A-C+B-D CH3-CI+ NaOH H20 Ch3oh+ naCl H H-C-H Cl-Cl H-C-Cl +H-Cl H H Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 Substitutions (取代) Substitution reactions occur when two reactants exchange parts to give two new products. In a substitution, one replaces another. A B + C D A C + B D CH3 Cl + NaOH CH3 OH + NaCl H2O H C H H H + Cl Cl hv H C H H Cl + H Cl

ORGANIC CHEMISTRY Chapter 3 Additions(加成) g Addition reactions occur when two reactants add together to form a single new product with no atoms“ left over? o In an addition all parts of the adding reagent appear in the product; two molecules become one A +B C Br Bi CHo=CHo Br-Br CH -CH, H Br CH2=CH2+H-Br—CH2-Cl Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 Additions (加成) Addition reactions occur when two reactants add together to form a single new product with no atoms “left over”. In an addition all parts of the adding reagent appear in the product;two molecules become one A + B C CH2 CH2 + Br Br CH2 CH2 Br Br CH2 CH2 + H Br CH2 CH2 H Br

ORGANIC CHEMISTRY Chapter 3 Eliminations(消除) o Eliminations are the opposite of additions Eliminations occur when a single reactant splits apart into two products g In an eliminations one molecule loses the elements of another small molecule A B + C H Br NaOH CH2-CH2 CH-CH, H-Br Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 Eliminations (消除) Eliminations are the opposite of additions. Eliminations occur when a single reactant splits apart into two products. In an eliminations one molecule loses the elements of another small molecule. A B + C CH CH2 CH2 + H Br 2 CH2 H Br NaOH

ORGANIC CHEMISTRY Chapter 3 Rearrangement(重排) o rearrangement reactions occur when a single reactant undergoes a reorganization of bonds and atoms to yield an isomeric product A B H H2C、C=C、 CH CH3 C-C H3C CH3 CH3 CH3 Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 Rearrangement (重排) Rearrangement reactions occur when a single reactant undergoes a reorganization of bonds and atoms to yield an isomeric product. A B C C C H3C H3C CH3 H H+ H H C C CH3 CH3 CH3 CH3

ORGANIC CHEMISTRY Chapter 3 Mechanisms of reactions A reaction mechanism(反应机理) o- An overall description of how a specific reaction occur o-a description of the events that take place on a molecular level as reactions become products CH CH CH C OH CH3C—Cl-CH2C+ CH3-C-OH CH CH CH3 (a) More than I step (b)Intermediates Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 Mechanisms of Reactions A reaction mechanism (反应机理) — An overall description of how a specific reaction occur. — A description of the events that take place on a molecular level as reactions become products. CH3 C CH3 CH3 Cl CH3 C CH3 CH3 Cl CH3 C CH3 CH3 OH OH (a) More than 1 step (b) Intermediates

ORGANIC CHEMISTRY Chapter 3 3. 1A Homolysis and Heterolysis of Covalent bonds(共价键的均裂和异裂) o Reactions of organic compounds al ways involve the making and breaking of covalent bonds o a covalent bond may break in two fundamentally different ways Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 3.1A Homolysis and Heterolysis of Covalent Bonds (共价键的均裂和异裂) Reactions of organic compounds always involve the making and breaking of covalent bonds. A covalent bond may break in two fundamentally different ways

ORGANIC CHEMISTRY Chapter 3 Homolysis o a bond breaks in an electronically symmetrical way so that each fragment takes away one of the electrons of the bond a-B A.+ B. Homolytic bond cleavage Free radicals or radicals Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 3 Homolysis A bond breaks in an electronically symmetrical way so that each fragment takes away one of the electrons of the bond. A B A + B Homolytic bond cleavage Free radicals or radicals