CH3CH2CH H Organic Chemistry, 5th Edition BrC.h L.G. Wade jr Chapter 11 Reactions of alcohols Jo blackburn Richland college, dallas TX Dallas County Community College District c 2003. Prentice hall
CH3CH2CH2 C H H Br O H H Chapter 11 Reactions of Alcohols Jo Blackburn Richland College, Dallas, TX Dallas County Community College District © 2003, Prentice Hall Organic Chemistry, 5th Edition L. G. Wade, Jr
CH3 CH2CH 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
CH3CH2CH2 C H H Br O H H 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 =>
CH3CH2CH H H Summary Table HH TABLE 11-1 Types of Reactions of Alcohols R-OH type of reaction Product dehydration esterification R—OH alkenes R—OH R-0—C-R oxidation R—OH ketones, aldehydes, acids R—OH tosylation R-OTS substitution R-OH R一X tosylate esters (good leaving group halides reduction R—OH R—H R-OH (1) form alkoxide R-0—R′ (2)RX alkanes ethers Chapter 11
CH3CH2CH2 C H H Br O H H Chapter 11 3 Summary Table =>
CH3CH2CH H H Oxidation States HH Easy for inorganic salts >CrO4- reduced to Cr2O3 >KMnO4 reduced to MnO2 Oxidation: loss of H2, gain of O, O2, or X2 Reduction: gain of H2 or H, loss ofo, o23 orⅩ2 Neither: gain or loss of H+, H2O, HX Chapter 11
CH3CH2CH2 C H H Br O H H Chapter 11 4 Oxidation States • Easy for inorganic salts ➢CrO4 2- reduced to Cr2O3 ➢KMnO4 reduced to MnO2 • Oxidation: loss of H2 , gain of O, O2 , or X2 • Reduction: gain of H2 or H- , loss of O, O2 , or X2 • Neither: gain or loss of H+ , H2O, HX =>
CH3CH2CH H 10,20,3° Carbons0H OXIDATION H OH R一C—H R一C一H O R—C—H O R-C-OH +Ho H H alkane primary alcohol aldehyde carboxylic acid no bonds to o one bond to o two bonds to o three bonds to o OH R—C-p,Ol →R—C-RO R—C-R′( no further +H, H alkane secondary alcohol ketone no bonds to o one bond to o two bonds to o H OH RC-R、R-C一R( sually no further oxidation) R alkane tertiary alcohol no bonds to o one bond to o REDUCTION
CH3CH2CH2 C H H Br O H H Chapter 11 5 1º, 2º, 3º Carbons =>
CH3CH2CH H Br…C--O Oxidation of 2 AlcohO/s HH ·2°a| cohol becomes a ketone Reagent is Na2Cr2O, H2SO4 Active reagent probably H2CrO4 Color change: orange to greenish-blue Na2 Cr2O7/H2SO4 CH3 CHCH2CH3 i CH3 CCH2CH3 Chapter 11
CH3CH2CH2 C H H Br O H H Chapter 11 6 Oxidation of 2° Alcohols • 2° alcohol becomes a ketone • Reagent is Na2Cr2O7 /H2SO4 • Active reagent probably H2CrO4 • Color change: orange to greenish-blue CH3 CHCH2 CH3 OH Na2 Cr 2 O7 / H2 SO4 CH3 CCH2 CH3 O =>
CH3 CH2CH H Oxidation of 1 alcohols H HH 1 alcohol to aldehyde to carboxylic acid Difficult to stop at aldehyde Use pyridinium chlorochromate(PCC) to limit the oxidation PCC can also be used to oxidize 2 alcohols to ketenes OH N一HCrO3Cl CH3 CH2 CH2 CH3 CH CHCH Chapter 11
CH3CH2CH2 C H H Br O H H Chapter 11 7 Oxidation of 1° Alcohols • 1° alcohol to aldehyde to carboxylic acid • Difficult to stop at aldehyde • Use pyridinium chlorochromate (PCC) to limit the oxidation. • PCC can also be used to oxidize 2° alcohols to ketones. CH3CH2CH2CH2 OH N H CrO3Cl CH3CH2CH2CH O =>
CH3CH2CH2 H 3 Alcohols dont oxidize hh Cannot lose 2h's Basis for chromic acid test Summary of Alcohol Oxidations To Oxidize Product Reagent 2° alcohol ketone chromic ac id(or PCC) alcohol aldehyde PCC ° alcohol ac chromic ac Chapter 11
CH3CH2CH2 C H H Br O H H Chapter 11 8 3° Alcohols Don’t Oxidize • Cannot lose 2 H’s • Basis for chromic acid test =>
CH3CH2CH2 H Br…C Other Oxidation Reagents HH H Collins reagent: Cr2O3 in pyridine Jones reagent: chromic acid in acetone KMnO(strong oxidizer) Nitric acid(strong oxidizer) CuO,300°c( industrial dehydrogenation) Swern oxidation: dimethylsulfoxide, with Oxalyl chloride and hindered base AA s7 oxidizes 2 alcohols to ketones and alcohols to aldehydes
CH3CH2CH2 C H H Br O H H Chapter 11 9 Other Oxidation Reagents • Collins reagent: Cr2O3 in pyridine • Jones reagent: chromic acid in acetone • KMnO4 (strong oxidizer) • Nitric acid (strong oxidizer) • CuO, 300°C (industrial dehydrogenation) • Swern oxidation: dimethylsulfoxide, with oxalyl chloride and hindered base, oxidizes 2 alcohols to ketones and 1 alcohols to aldehydes. =>
CH3CH2CH2 Biological Oxidation斷0H H HH Catalyzed by ADh, alcohol dehydrogenase Oxidizing agent is NAD*t, nicotinamide adenine dinucleotide Ethanol oxidizes to acetaldehyde then acetic acid. a normal metabolite Methanol oxidizes to formaldehyde then formic acid. more toxic than methanol Ethylene glycol oxidizes to oxalic acid, toxic Treatment for poisoning is excess ethanol Chapter 11 10
CH3CH2CH2 C H H Br O H H Chapter 11 10 Biological Oxidation • Catalyzed by ADH, alcohol dehydrogenase. • Oxidizing agent is NAD+ , nicotinamide adenine dinucleotide. • Ethanol oxidizes to acetaldehyde, then acetic acid, a normal metabolite. • Methanol oxidizes to formaldehyde, then formic acid, more toxic than methanol. • Ethylene glycol oxidizes to oxalic acid, toxic. • Treatment for poisoning is excess ethanol. =>
