《有机化学》课程PPT教学课件（Organic Chemistry, William A. Price, Ph.D. PPT, La Salle University, L.G.WADE, JR., 8th Edition）Reactions of Alcohols

Reactions of alcohols Oxidation R-X,Ether,and Ester Preparation Protection of Alcohols Synthesis The Logic of Mechanisms

Reactions of Alcohols Oxidation R-X, Ether, and Ester Preparation Protection of Alcohols Synthesis The Logic of Mechanisms

Alcohols are Synthetically Versatile TABLE 11-1 Types of Reactions of Alcohols R-OH type of reaction Product dehydration esterification R一OH alkenes R一OH R一O一( R esters oxidation R-OH ketones,aldehydes, acids tosylation R一OH R-OTs substitution R一OH R—X tosylate esters (good leaving group) halides reduction (1)form alkoxide R一OH R一H R一OH R-O一R' (2)R'X alkanes ethers

Alcohols are Synthetically Versatile

Oxidation levels of oxygen-halogen-and nitrogen- containing molecules CH2-CH2 HC-CH [O] CH:CH2OH [O] CH3CH=O CH3CO2H CH3CH3 [O] CHCH>CI CH:CHCI CH;CCls CH:CH2NH2 CH:CH=NH CH3CN Oxidation Reduction

Oxidation levels of oxygen- halogen- and nitrogen￾containing molecules Reduction Oxidation C H3C H3 C H2 =CH2 HC CH [O] [O] C H3C H2OH CH3CH=O CH3C O2H C H3C H2Cl CH3CHCl2 CH3CCl3 C H3C H2N H2 CH3CH=NH CH3C N [O]

Oxidation Reduction OXIDATION H OH R一C H -OH H + H20 alkane primary alcohol aldehyde carboxylic acid no bonds to O one bond to O two bonds to O three bonds to O H OH R一CR' IO R-C-R IO R-C-R' (no further H + H2O oxidation) alkane secondary alcohol ketone no bonds to O one bond to O two bonds to O H OH R一C一 R RC 个 (usually no further oxidation) R" R" alkane tertiary alcohol no bonds to O one bond to O REDUCTION

Oxidation - Reduction

Oxidation of 2 Alcohols with Cr(VI) OH R—CH—R' NazCr2O-/H2SO4_ secondary alcohol ketone OH NazCrO1 HSO4 cyclohexanol cyclohexanone (90%6)

Oxidation of 2o Alcohols with Cr(VI)

Mechanism Na2Cr207+H20+2H2S04 2 H2CrO4 2 NaHSO4 OCrO3H HO- + H2O 2°alcohol Chromic Acid(CrV④ Chromate ester 6H2 ke tone (Cr IV)

Mechanism OH + C r O O HO OH OCrO3H Chromate ester + H2O N a2 C r2O7 + H2O + 2 H2 SO4 2 H2CrO4 + 2 NaHSO4 Chromic Acid (Cr VI) H O CrO3H O H2 O + H3O + HCrO3 2 alcohol o ketone (Cr IV)

Oxidation of 1 Alcohols CH,OH 一OH NaCr207 H2SO4 cyclohexyl methanol cyclohexanecarboxylic acid (92%)

Oxidation of 1o Alcohols

PCC oxidizes 1 Alcohols to Aldehydes cro.c H PCC pyridinium chlorochromate

PCC oxidizes 1o Alcohols to Aldehydes N H CrO3 C l pyridinium chlorochromate PCC

Pyridinium Chlorochromate (PCC) ·PCC is a complex of chromium trioxide, Pyridinium chlorochromate (PCC): pyridine,and HCI. ·Oxidizes primary N+H CrO,CI- alcohols to aldehydes. CrO3'pyridine·HCI Oxidizes secondary or pyH+CrO,CI- alcohols to ketones

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

Oxidation of 1 Alcohols to Aldehydes:PCC OH CrO3'pyridine-HCl(PCC) R-C-H R-C-H CH2Cl2 H primary alcohol aldehyde pyH+CrO3CI-(PCC) CH,(CH2)5一CH2OH CH2Cl2 CH3(CH2)s-C-H 1-heptanol heptanal (78%)

Oxidation of 1o Alcohols to Aldehydes: PCC