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1、15.6 Reactions of Alcohols: A Review and a Preview,Table 15.2 Review of Reactions of Alcohols,reaction with hydrogen halides reaction with thionyl chloride reaction with phosphorous tribromide acid-catalyzed dehydration conversion to p-toluenesulfonate esters,New Reactions of Alcohols in This Chapte
2、r,conversion to ethers esterification esters of inorganic acids oxidation cleavage of vicinal diols,15.7 Conversion of Alcohols to Ethers,H+,+,Conversion of Alcohols to Ethers,acid-catalyzed referred to as a “condensation“ equilibrium; most favorable for primary alcohols,Example,2CH3CH2CH2CH2OH,CH3C
3、H2CH2CH2OCH2CH2CH2CH3,(60%),Figure 15.2 Mechanism of Formation of Diethyl Ether,Step 1:,H,CH3CH2O, ,H,OSO2OH,H,+,+,Figure 15.2 Mechanism of Formation of Diethyl Ether,Step 2:,+,Figure 15.2 Mechanism of Formation of Diethyl Ether,Step 3:,+,reaction normally works well only for 5- and 6-membered rings
4、,Intramolecular Analog,HOCH2CH2CH2CH2CH2OH,H2SO4,130,O,(76%),Intramolecular Analog,HOCH2CH2CH2CH2CH2OH,H2SO4,130,O,(76%),via:,15.8 Esterification,condensation Fischer esterification acid catalyzed reversible,Esterification,ROH,H2O,+,H+,+,Example of Fischer Esterification,H2O,+,0.1 mol,0.6 mol,70% yi
5、eld based on benzoic acid,high yields not reversible when carried out in presence of pyridine,Reaction of Alcohols with Acyl Chlorides,ROH,HCl,+,+,pyridine,+,(63%),Example,analogous to reaction with acyl chlorides,Reaction of Alcohols with Acid Anhydrides,ROH,+,+,pyridine,(83%),Example,15.9 Esters o
6、f Inorganic Acids,Esters of Inorganic Acids,ROH + HOEWG,ROEWG + H2O,EWG is an electron-withdrawing group,HONO2,(HO)2SO2,Esters of Inorganic Acids,ROH + HOEWG,ROEWG + H2O,EWG is an electron-withdrawing group,HONO2,(HO)2SO2,CH3OH + HONO2,CH3ONO2 + H2O,(66-80%),15.10 Oxidation of Alcohols,Primary alcoh
7、ols,Secondary alcohols,from H2O,Oxidation of Alcohols,RCH2OH,RCH,RCOH,RCR,Aqueous solution Mn(VII) Cr(VI) KMnO4 H2CrO4 H2Cr2O7,Typical Oxidizing Agents,Aqueous Cr(VI),FCH2CH2CH2CH2OH,K2Cr2O7,H2SO4,H2O,FCH2CH2CH2COH,(74%),Aqueous Cr(VI),FCH2CH2CH2CH2OH,K2Cr2O7,H2SO4,H2O,FCH2CH2CH2COH,(74%),Na2Cr2O7,H
8、2SO4,H2O,(85%),O,All are used in CH2Cl2 Pyridinium dichromate (PDC) (C5H5NH+)2 Cr2O72 Pyridinium chlorochromate (PCC) C5H5NH+ ClCrO3,Nonaqueous Sources of Cr(VI),Example: Oxidation of a primary alcohol with PCC,CH3(CH2)5CH2OH,PCC,CH2Cl2,(78%),ClCrO3,PDC,CH2Cl2,(94%),Example: Oxidation of a primary a
9、lcohol with PDC,Mechanism,involves formation and elimination of a chromate ester,C,OH,HOCrOH,C,O,H,H,CrOH,Mechanism,involves formation and elimination of a chromate ester,C,OH,HOCrOH,C,O,H,H,CrOH,15.11 Biological Oxidation of Alcohols,alcohol dehydrogenase,Enzyme-catalyzed,CH3CH2OH,+,+,+,nicotinamide adenine dinucleotide (oxidized form),Figure 15.3 Structure of NAD+,Enzyme-catalyzed,CH3CH2OH,+,+,Enzyme-catalyzed,N,H,R,H,15.12 Oxidative Cleavage of Vicinal Diols,Cleavage of Vicinal Diols by Periodic Acid,C,+,Cleavage of Vicinal Diols by Periodic Acid,HIO4,+,(83%),Cyclic Diols are Cleaved,HIO4,
