《有机化学》课程PPT教学课件（Official PPT of Organic Chemistry, 7th Edition, L. G. Wade, Jr.Pearson Education）Chapter 11 Reactions of Alcohols

CH3CH2CH2 Organic Chemistry,7th Edition HH L.G.Wade,Jr. Chapter 11 Reactions of Alcohols Copyright 2010 Pearson Education,Inc

Chapter 11 Reactions of Alcohols Copyright © 2010 Pearson Education, Inc. Organic Chemistry, 7th Edition L. G. Wade, Jr. CH3CH2CH2 C H H Br O H H

Types of Alcohol Reactions Dehydration to alkene Oxidation to aldehyde,ketone Substitution to form alkyl halide ·Reduction to alkane ·Esterification ·Tosylation Williamson synthesis of ether Chapter 11 2

Chapter 11 2 Types of Alcohol Reactions • Dehydration to alkene • Oxidation to aldehyde, ketone • Substitution to form alkyl halide • Reduction to alkane • Esterification • Tosylation • Williamson synthesis of ether

Summary Table TABLE 11-1 Types of Reactions of Alcohols R-OH type of reaction Product dehydration R一OH alkenes R-OH esterification R-OCR esters oxidation R-OH ketones,aldehydes, acids tosylation R-OH R-OTs substitution R-OH R-X tosylate esters halides (good leaving group) reduction (1)form alkoxide R-OH R-H R-OH R-O-R' alkanes (2)RX ethers Copyright 2010 Pearson Prentice Hall,Inc. Chapter 11 3

Chapter 11 3 Summary Table

Oxidation States Easy for inorganic salts: CrO42-reduced to Cr2O3. -KMnO4 reduced to MnO2. .Oxidation:Gain of O,O2,or X2;loss of H2. Reduction:Gain of H2 (or H);loss of O or O2; and loss of X2. The gain or loss of H+,H2O,HX,etc.is neither an oxidation nor a reduction. Chapter 11 4

Chapter 11 4 Oxidation States • Easy for inorganic salts: ▪ CrO4 2- reduced to Cr2O3 . ▪ KMnO4 reduced to MnO2 . • Oxidation: Gain of O, O2 , or X2 ; loss of H2 . • Reduction: Gain of H2 (or H- ); loss of O or O2 ; and loss of X2 . • The gain or loss of H+ , H2O, HX, etc. is neither an oxidation nor a reduction

Oxidation States of Carbons OXIDATION H OH 0 R-C-H IO,R-C-H,R-C-H,R-C-OH +H0 aldehyde no bonds to H 0 R-C-R'10L,R-C-R'1O R-C-R'(0o furtber oxidntion) H +H,O alkane secondary alcohol ketone no bonds to O one bond toO two honds toO H OH R一C-R'IoLR一C一R'ualyno fher oxidation) R“ R" alkane tertiary alcohol no bonds to O one bond to O REDUCTION Copyright 2010 Pearson Prentice Hall.Inc Chapter 11 5

Chapter 11 5 Oxidation States of Carbons

Oxidation of 2 Alcohols 。2° alcohol becomes a ketone. OH NazCr2O/H,SO R-CH-R' R -R ·Oxidizing agent is secondary alcohol ketone Na2Cr207/H2S04: Example H ·Active reagent NazCr2O7 OH H,S04 probably is H2CrO4. cyclohexanol cyclohexanone (90%) ·Color change is orange to greenish- blue. Chapter 11 6

Chapter 11 6 Oxidation of 2° Alcohols • 2° alcohol becomes a ketone. • Oxidizing agent is Na2Cr2O7 /H2SO4 . • Active reagent probably is H2CrO4 . • Color change is orange to greenish￾blue

Oxidation Mechanism Formation of the chromate ester R一CO一H H-O-Cr-OH R OH H 0 alcohol chromic acid chromate ester Elimination of the chromate ester and oxidation of the carbinol carbon R R R OH R-C ' H2O:H .0. H.O 0 Cr(VI) Cr(IV) Copyright2010 Pearson Prentice Hall,Inc. Chapter 11 7

Chapter 11 7 Oxidation Mechanism

Oxidation of 1 Alcohols to Carboxylic Acids CH,OH C一OH NaCr2O7 H2SO4 cyclohexyl methanol cyclohexanecarboxylic acid (92%) Chromic acid reagent oxidizes primary alcohols to carboxylic acids. The oxidizing agent is too strong to stop at the aldehyde. Chapter 11 8

Chapter 11 8 Oxidation of 1° Alcohols to Carboxylic Acids • Chromic acid reagent oxidizes primary alcohols to carboxylic acids. • The oxidizing agent is too strong to stop at the aldehyde

Pyridinium Chlorochromate (PCC) Pyridinium chlorochromate (PCC). CrO,C1 CrO3'pyridine·HCI or pyH+CrOCI- Copyright010Pearson Prne Hall Inc PCC is a complex of chromium trioxide, pyridine,and HCI. Oxidizes primary alcohols to aldehydes. Oxidizes secondary alcohols to ketones. Chapter 11 9

Chapter 11 9 Pyridinium Chlorochromate (PCC) • PCC is a complex of chromium trioxide, pyridine, and HCl. • Oxidizes primary alcohols to aldehydes. • Oxidizes secondary alcohols to ketones

Pyridinium Chlorochromate (PCC) OH CrO3'pyridine-HCI(PCC) R一C一H R- 一H CH2Cl2 H primary alcohol aldehyde Example 0 PCC CH3(CH2)s-CH2OH CH2C12 CH3(CH2)5-C一H 1-heptanol heptanal(78%) Copyright2010 Pearson Prentice Hall,Inc. Chapter 11 10

Chapter 11 10 Pyridinium Chlorochromate (PCC)