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. =>