有机化学14二羰基化合物.ppt

14 β—二羰基化合物;β-二羰基化合物: 指两个羰基被一个碳原子隔开的一类化合物。;Compounds having two carbonyl groups separated by an intervening carbon are called β-dicarbonyl compounds, and these compounds are highly versatile reagents for organic synthesis. ;Central to the chemistry of β-dicarbonyl compounds is the acidity of protons located on the carbon between two carbonyl groups. The pKa for such a proton is in the range 9-11. ;§14.1 酮-烯醇互变结构; 酮式 烯醇式 沸点：41℃(267Pa) 33℃(267Pa) ;共振杂化体;（一）酮烯醇互变异构;§14.1.1 酸和碱对酮-烯醇平衡的影响;碱催化：;§14.1.2 化合物的结构对酮-烯醇平衡的影响;某些化合物中烯醇式含量;有 机 化 学;有 机 化 学;§14.1.3 烯醇化导致立体异构化;有 机 化 学;有 机 化 学;有 机 化 学;A Mechanism For The Dieckmann Condensation;有 机 化 学;Predict the product from the base–catalyzed condensation of two molecules of ethyl acetate:;First, form the enolate.;;The enolate attacks a second mole of the ester;This yields a tetrahedral intermediate. Expulsion of ethoxide gives final product.;The final product is a ethyl acetoacetate. This reaction is called the Claisen Condensation.;Predict the major product for the reaction shown above.;The enolate of one end attacks the other ester carbonyl to give a tetrahedral intermediate…;…Which breaks down with expulsion of methoxide.;…which breaks down with expulsion of methoxide.;;Predict the product from the base-catalyzed condensation of ethyl acetate and ethyl benzoate:;The enolate attacks ethyl benzoate… ;…to yield a tetrahedral Intermediate. Expulsion of ethoxide gives the final product.;This reaction is a mixed Claisen Condensation.;§14.2.2乙酰乙酸乙酯的性质;二、酸式分解：浓碱作用下;三、烷基取代活泼亚甲基中的氢原子;有 机 化 学;有 机 化 学;1-苯基-1, 3-丁二酮;有 机 化 学;(first alkylation);4-Oxopentanoic acid;+;(- );有 机 化 学;有 机 化 学;三、制备二元酸：;四、制备环烷酸：;§14.4 Knoevenagel（诺文葛耳）缩合;The knoevenagel reaction is an aldol-like reaction in which ketones and aldehydes react with diethyl malonate(丙二酸二乙酯) to give an α-β-unsaturat