Acetoacetate ester condensation

The acetoacetic ester condensation (involving the acylation of an ester by an ester) is a special case of a more general reaction term the Claisen condensation. The latter is the condensation between a carboxylic ester and an ester (or ketone or nitrile) containing an a-hydrogen atom in the presence of a base (sodium, sodium alkoxide, sodamide, sodium triphenylmethide, etc.). If R—H is the compound containing the a- or active hydrogen atom, the Claisen condensation may be written ... 

Simple esters (e.g., ethyl acetate) undergo the acetoacetic ester condense tion (compare Section 111,151). The effective condensing agent is sodium ethoxide, produced by the action of sodium upon traces of alcohol present in the ester ... 

The formation of acyloins (a-hydroxyketones of the general formula RCH(OH)COR, where R is an aliphatic residue) proceeds best by reaction between finely-divided sodium (2 atoms) and esters of aliphatic acids (1 mol) in anhydrous ether or in anhydrous benzene with exclusion of oxygen salts of enediols are produced, which are converted by hydrolysis into acyloins. The yield of acetoin from ethyl acetate is low (ca. 23 per cent, in ether) owing to the accompanying acetoacetic ester condensation the latter reaction is favoured when the ester is used as the solvent. Ethyl propionate and ethyl ji-butyrate give yields of 52 per cent, of propionoin and 72 per cent, of butyroin respectively in ether. 

Acetoacetic ester condensation Amdt-Eistert reaction Bart reaction. ... 

Carboxylic esters 1 that have an a-hydrogen can undergo a condensation reaction upon treatment with a strong base to yield a /3-keto ester 2. This reaction is called the Claisen ester condensation or acetoacetic ester condensation, the corresponding intramolecular reaction is called the Dieckmann condensation ... 

Esters of dicarboxylic acids having hydrogen on the 8 or e carbon atcans undergo intramolecular cyclisation when heated with sodium or with sodium ethoxide. This cyclisation is known as the Dieckmaim reaction. It is essentially an application of the Claiseu (or acetoacetic ester) condensation to the formation of a ring system the condensation occurs internally to produce s... 

The mechanism of the base-cataljrsed acylation of ketones by esters probably involves several steps (compare acetoacetic ester condensation see discussion prior to Section 111,151) —... 

The Acetoacetic Ester Condensation and Certain Related Reactions. 

Reagent in the Acetoacetic Ester Condensation. J. Amer. chem. Soc. 59 2009 (1937). 

Acetoacetic Ester can be prepared by the condensation of ethyl acetate, called the Acetoacetic Ester Condensation Reaction, a Claisen Condensation-. 

Acetoacetic ester condenses with aldehydes at S-IO in the presence of piperidine, piperidine acetate, or acetamide. Several olefinic -keto esters have been made in this way for example, ethyl butylideneaceto-acetate (81%). ... 

The acetoacetic ester condensation consists of a base-catalyzed reaction of two esters (at least one having an a-hydrogen atom) to form a /3-keto ester. The scope, limitations, experimental procedures, and applications have been reviewed. ... 

Hauser, C. R., Hudson, B. E., Jr. Acetoacetic ester condensation and certain related reactions. Org. React. 1942,1,266-302. 

For a review of the Claisen or acetoacetic ester condensation, see Hauser and Hudson, in Adams, Organic Rcactionsy Vol. I, p. 266, John Wiley and Sons, New York, 1942. 

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