Ethyl acetoacetate alcohol

This Reaction should be carefully distinguished from the Claisen Conden-tation, which is the condensation of an ester, under the influence of sodium ethoxide, with (i) another ester, (ii) a ketone, or (iii) a nitrile, with the elimination of alcohol. For details of this condensation, see Ethyl Acetoacetate, p. 264. 

Ethyl acetoacetate may be prepared by the action of sodium upon dry ethyl acetate and decomposition of the resulting sodio compound with dilute acetic acid. Most samples of ethyl acetate contain some ethyl alcohol and it is usually assumed that sodium ethoxidc is the condensing agent ... 

Heat a mixture of 0-5 g. of ethyl acetoacetate and an equivalent amount of phenylhydrazine in an oil bath at 100-110° for 2 hours. Water and alcohol vapours are evolved. Cool and recrystallise the product from alcohol. The resulting phenyhnethylpyrazolone has m.p. 127°. 

When ethyl acetoacetate is warmed with an equivalent quantity of phenyl-hydrazine, the compound (I), which is not a true hydrazone, is first formed this undergoes ring formation (II) with loss of ethyl alcohol upon further heating. The product (II) is N or l-phenyl-3-methyl-5-pyrazolone. 

The ester 322A is made by ester exchange with ethyl acetoacetate and a suitable alcohol. The product 322B decarboxylates spontaneously on heating. Draw out the whole sequence starting from ethyl acetoacetate. 

P-Ketoester Chelates. p-Ketoesters react in a fashion similar to the p-diketones. TYZOR DC [27858-32-8] is the hght-yeUow Hquid from TYZOR TPT and two moles of ethyl acetoacetate (eaa) after removal of the isopropyl alcohol. TYZOR BEAT, the bis-ethylacetoacetate [20753-28-0] derived from the tetra- -butyl titanate, and TYZOR IBAY [83877-91-2] the isobutoxy analogue, perform similarly to TYZOR DC. Both, however, have better cold-storage stabiHty. 

To 500 g. (3.85 moles) of freshly distilled ethyl acetoacetate in a i-l. flask set in ice and well cooled, are added 152 g. (2.0 moles) of 40 per cent aqueous formaldehyde solution and 20-25 drops of diethylamine. The flask and contents are kept cold for six hours and are then allowed to stand at room temperature for forty to forty-five hours. At the end of this time two layers are present, a lower oily layer and an upper aqueous layer. The layers are separated, and the aqueous layer is extracted with 50 cc. of ether. The ether solution is added to the oily layer, and the resulting solution is dried over 30 g. of calcium chloride. The ether is then removed by distillation on a steam bath. The residue, amounting to approximately 500 g., is diluted with an equal volume of alcohol and is thoroughly cooled in an ice bath. Ammonia is then passed into the mixture until the solution is saturated. This requires from four to eight hours, and during this time the flask is kept packed in ice. The ammoniacal alcoholic solution is allowed to stand at room temperature for forty to forty-five hours. Most of the alcohol is now evaporated the residue is cooled, and the solid i,4-dihydro-3,5-dicarbethoxy-2,6-dimethylpyridine is removed from the remaining alcohol on a suction filter. The dried ester melts at 175-180 and amounts to 4ro-435 g. (84-89 per cent of the theoretical amount). 

The contents of the flask while still hot are poured into a 30-cm. evaporating dish and the alcohol is evaporated on a steam bath. The dry salt is pulverized and thoroughly mixed with 390 g. of calcium oxide, placed in a 2-I. copper retort (Note 3), and heated with the full flame of a Meker burner. The distillate is placed in a distilling flask and heated on a steam bath all material distilling under 90 is removed and discarded. The residue is then allowed to stand over solid potassium hydroxide for twelve hours and is finally fractionated. The dimethyl-pyridine distils at i42-i44°/743 mm. The yield is 35-36 g. or 62-64 per cent of the theoretical amount based on the 3,5-dicarb-ethoxy-2,6-dimethylpyridine, or 30-36 per cent based on the original ethyl acetoacetate. 

In a 3-I. three-necked, round-bottomed flask fitted with a mechanical stirrer, reflux condenser, and separatory funnel is placed 400 cc. of absolute alcohol (Note i). Through the condenser tube is added slowly, 23 g. (i gram atom) of dean sodium cut into thin slices. The completion of the reaction is hastened by heating the flask on a steam bath. When the sodium has dissolved completely, 143 g. (i.i moles) of ethyl acetoacetate is introduced slowly. Alter starting the mechanical stirrer, 123 g. (i mole) of ethyl chloroacetate (Note 2) is added slowly over a period of an hour, and the reaction mixture is refluxed for five to six hours. At this point the reaction mixture should no longer give an alkaline reaction with moist litmus. 

The formation of ethyl acetoacetate occurs, according- to Claisen, in four steps. The presence of a small quantity of alcohol gives lise to sodium ethylate, which forms an additive compound with ethyl acetate. The latter unites with a second molecule of ethyl acetate yielding the sodium salt of ethyl acetoacetate, and splitting off alcohol, which reacts with fresh metallic sodium. The sodium salt on acidifying passes into the tautomeric (ketonic) form of acetoacetic ester. 

The proposed mechanism for the Conrad-Limpach reaction is shown below. Condensation of an aniline with a 3-keto-ester (i.e., ethyl acetoacetate 5) with loss of water provides enamino-ester 6. Enolization furnishes 10 which undergoes thermal cyclization, analogous to the Gould-Jacobs reaction, via 6n electrocyclization to yield intermediate 11. Compound 11 suffers loss of alcohol followed by tautomerization to give 4-hydroxy-2-methylquinoline 7. An alternative to the proposed formation of 10 is ejection of alcohol from 6 furnishing ketene 13, which then undergoes 671 electrocyclization to provide 12. 

A -acetyl groups attached to the aniline have been shown to withstand the Conrad-Limpach reaction. Phenols and alcohols also survived unless in proximity to a reactive center. Jaroszewski reported the formation of 64 by reaction of aniline 63 with ethyl acetoacetate (5). Cyclization under thermal conditions in paraffin gave a mixture of quinolone 65 and quinoline 66. 

The mercaptals obtained by the acid catalyzed reaction of J3-ketoesters, e.g., ethyl acetoacetate, with methyl thioglycolate (73) undergo the Dieckmann cyclization with alcoholic potassium hydroxide at lower temperatures to give ethyl 3-hydroxy-5-methyl-2-thiophenecarboxylate (74) in 75% yield. ° Besides ethyl acetoacetate, ethyl a-ethylacetoacetate, ethyl benzoyl acetate, and ethyl cyclopentanonecarboxylate were also used in this reaction/ It is claimed that /8-diketones, hydroxy- or alkoxy-methyleneketones, or /8-ketoaldehyde acetals also can be used in this reaction. From acetylacetone and thioglycolic acid, 3,5-dimethyl-2-thiophenecarboxyl-ic acid is obtained. ... 

Ethyl Acetoacetate (Coll. Vol. x, 230) It is reported that, when the condensation is carried out in such a manner as to remove the alcohol formed in the reaction, the yield is 80 per cent of the theoretical amount. Roberts and McElvain, J. Am. Chem. Soc. 59, 2007 (1937),... 

P-Keto esters (e.g., ethyl acetoacetate) are soluble in solutions of caustic alkalis but not in sodium carbonate solution. They give colours with freshly prepared ferric chloride solution a little alcohol should be added to bring the ester into solution. Sodium ethoxide solution reacts to yield sodio compounds, which usually crystallise out in the cold. Phenylhydrazine yields pyrazolones. They are hydrolysed by boiling sulphuric acid to the Corresponding ketones, which can be identifi as usual (Section 111,74). 

Commercial cycZopropyl methyl ketone (Matlieson Company) is redistiUed through a Widmer column over 95 per cent, passes over at llO-S-lll-S /767 mm. It is quite pure since it yields a semicarbazone, m.p. 117° the m.p. is unaffected by recrystallisation from aqueous alcohol. The ketone may be prepared from ethylene dibromide, ethyl acetoacetate and an excess of sodium ethoxide. 

The patent describes the formation of complex metal chelates by treatment of the ketoester simultaneously with an alcohol and a metal to effect trans-esterification and chelate formation by distilling out the by-product ethanol [1], This process was being applied to produce the zinc chelate of 2-tris(bromomethyl)ethyl acetoacetate, and when 80% of the ethanol had been distilled out (and the internal temperature had increased considerably), a violent decomposition occurred [2], This presumably involved interaction of a bromine substituent with excess zinc to form a Grignard-type reagent, and subsequent exothermic reaction of this with one or more of the bromo or ester functions present. 

A 2-1. three-necked flask is mounted on a steam bath and fitted with a reflux condenser, a separatory funnel, and an efficient sealed stirrer. In the flask is placed 600 cc. of absolute alcohol, and to this is added gradually 46 g. (2 gram atoms) of clean sodium cut into small pieces.1 The sodium ethoxide solution is stirred and cooled to room temperature, after which 267 g. (260 cc., 2.05 moles) of ethyl acetoacetate (Note 1) is added slowly through the separatory funnel. The reflux condenser is then replaced by a short still head, and the alcohol is removed by distillation at approximately room temperature and under the pressure of a water pump. When approximately half the alcohol has been removed, sufficient sodium enolate precipitates so that stirring has to be discontinued. When the residue appears dry (after about two hours) the last traces of alcohol are removed by heating for an hour on the steam bath under a pressure of 2 mm. The flask is allowed to cool to room temperature under reduced pressure. 

Other Methods of Preparation.—Ethyl 2-(D-ara6i no-tetrahydroxybutyl)-5-methyl-4-furoate has been prepared by heating D-glucose plus ethyl acetoacetate in aqueous alcohol without a catalyst,1 or from the same reagents (1 g. and 0.5 ml., respectively) in 0.5 ml. of 96% ethanol plus 1.5 ml. of water at room temperature in the presence of ferric chloride, zinc chloride (with small quantities of hydrochloric acid or of sodium hydroxide), cupric chloride, ferric sulfate, zinc sulfate, aluminum chloride, nickel chloride, or cobalt nitrate.18... 

A mixture of 2.65 g. of freshly distilled 2,3-O-isopropylidene-D-glycerose, 1.5 ml. of ethyl acetoacetate, 0.7 g. of zinc chloride, 20 ml. of N sulfuric acid, and 20 ml. of 96% ethyl alcohol is kept at room temperature for twenty-four hours. After addition of 3 g. of crystalline sodium acetate and keeping for a further 48 hours at room temperature, the mixture is heated for 15 minutes at 90°. It is then repeatedly extracted with ether, and the united extracts are successively washed with water, an aqueous solution of sodium bisulfite, and a small quantity of aqueous sodium hydroxide solution. The ether layer is dried with anhydrous sodium sulfate and the solvent is evaporated, yielding an oil which is saponified with aqueous sodium hydroxide solution (4 ml. of 10%) by heating on a steam bath for one hour. The aqueous solution is extracted with ether, acidified (to Congo Red) with phosphoric acid, and then repeatedly extracted with ether the united extracts are dried with anhydrous sodium sulfate and the solvent is evaporated, giving a residue which crystallizes from water yield, 0.2 g. of the product (X) m. p., 153-155°. 

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