[理学]醛 酮.ppt

第十二章 醛 酮 二、醛、酮的化学性质 (Chemical Properties of Aldehydes and Ketones) （3）卤仿反应 (Haloform reaction) Reactions of αhydrogens of aldehydes and ketones 乙醛、甲基酮（ ）和具有 结构的醇可发生卤仿反应，可用于这些化合物的鉴别 用于合成少一个碳原子的羧酸 Reactions of αhydrogens of aldehydes and ketones 3. 羟醛缩合 (Aldol condensations) β-羟基醛 3-羟基丁醛 β-Hydroxy aldehyde 3-Hydroxybutanal Reactions of αhydrogens of aldehydes and ketones 在稀碱溶液中，两分子有α-氢的醛互相结合生成β-羟基醛的反应。 机理 (Mechanism)： Reactions of αhydrogens of aldehydes and ketones 4. 与水加成 (Nucleophilic addition of water) 一般1, 1-二醇(Geminal diol)不稳定  Nucleophilic addition reaction of a nucleophile to the carbonyl group (1) 结构对平衡位置的影响 (Effects of Structure on Equilibrium) Stabilization: ＜ ＜ ＞ ＞  Nucleophilic addition reaction of a nucleophile to the carbonyl group Stabilization of hydrate:  Nucleophilic addition reaction of a nucleophile to the carbonyl group 三氯乙醛 水合三氯乙醛 δ- 茚三酮 (1, 2, 3-Indantrione) 水合茚三酮 (Ninhydrin) δ+ δ- δ+ δ+ δ-  Nucleophilic addition reaction of a nucleophile to the carbonyl group (Trichloroacetaldehyde) (Trichloroacetaldehyde hydrate) (2) 酸和碱的催化作用 (The role of acid and basic catalyst) 碱的存在不能改变平衡的位置, 只能加快达到平衡的速度 Base-catalyzed mechanism:  Nucleophilic addition reaction of a nucleophile to the carbonyl group Acid-catalyzed mechanism:  Nucleophilic addition reaction of a nucleophile to the carbonyl group 5. 与醇的加成 (Nucleophilic addition of alcohols) Hemiacetals or hemiketals 酸和碱对半缩醛（或半缩酮）的生成有催化作用 （1）半缩醛 (hemiacetals) 和半缩酮 (hemiketals)  Nucleophilic addition reaction of a nucleophile to the carbonyl group （2）缩醛和缩酮 (Acetals and ketals)  Nucleophilic addition reaction of a nucleophile to the carbonyl group 用途：保护羰基 (to protect the carbonyl group )  Nucleophilic addition reaction of a nucleophile to the carbonyl group 6. 与氮亲核试剂的加成 (Nucleophilic addition of nitrogen Nucleophiles) 肟 (oxime) 先加成后消去 (1) 与羟胺的加成 (Nucleophilic addition