郑州大学有机化学10醇醚课稿.ppt

(±) Ring Opening in Acid The reaction is SN1 like 10.9 Preparation 10.9.1 Acid-Catalyzed Intermolecular Dehydration of Alcohols If temperature is too high, alkene forms. 1o alcohols—SN2 2o and 3o alcohols—E1 10.9.2 The Williamson Synthesis of Ethers SN2 L= Br, I, OSO2R’’, OSO2OR’’ R’ ——CH3, primary or secondary alkyl SN1 二芳基醚用Ullmann反应合成 10.9.3 Acid-catalyzed Addition of Alcohols to Alkenes protecting group 乙烯基醚的合成 10.9.4 Alkoxymercuration of Alkenes (烯的烷氧汞化) 10.9.5 Preparation of Epoxides (环氧化合物的制备) Epoxidation of alkenes Base-promoted ring closure of vicinal halohydrins (碱促进下β-卤代醇的环合) 分子内SN2 racemate SUMMARY Alcols Nomenclature Reactions Preparation Ethers Nomenclature Reactions Preparation * * * * * * * * * * * * * 邻二醇( α-二醇), α-羟基醛/酮/酸, α-氨基醛/酮/酸, 1,2-二酮(α-二酮), 1-氨基-2-羟基化合物均可被高碘酸分解 × 很慢 Lead acetate (醋酸铅)：Pb(OAc)4 10.4.2 Pinacol Rearrangement (频哪醇重排) 1) 形成最稳定的碳正离子 Mechanism 2) 提供电子的基团发生迁移 3) 迁移基团与离去基团应处于反位 10.5 Preparation of Alcohols Alkenes Alkyl Halides Carbonyl Compounds Alcohols Grignard Synthesis 10.5.1 Via Hydrolysis of Alkyl Halides(通过卤代烃的水解) It is rarely used for the synthesis of alcohols, since alkyl halides are normally prepared from alcohols. 很少用卤代烃的水解来制备醇，因为多数情况下卤代烃比醇贵重，常用醇来制备卤代烃。 CH3Br + HO- → CH3OH + Br- (CH3)3CBr + H2O → (CH3)3COH + HBr RX + HO- → ROH + X- 10.5.2 Via Reactiontion of Alkenes (通过烯烃反应) Oxymercuration-demercuration of alkenes(烯烃的羟汞化-去汞化) The reactions take place very rapidly at room temperature; The overall reaction gives alcohols in very high yields, usually greater than 90%; Rearrangements of the carbon skeleton seldom occur. * Mercury compounds are extremely hazardous! Markovnikov addition anti addition (反式加成) Mechanism(机理) 10.5.3 Via Reduction of Carbonyl Compounds or Derivatives of Carboxylic Compounds (通过羰基化合物或羧酸衍生物还原) Hydrogenation (H2 with Raney nickel): Also reduces any C=C bonds Sodium in alcohol Lithium aluminum hydride (LiAlH4): reduces acids, esters, aldehydes, and ketones Sodium borohydride (NaBH4): reduces