Copper ethyl acetoacetate

Organometallic polymers with metals in the main chain can only be produced by polycondensation. In some of these reactions, the metal occurs in the monomer before the polycondensation step, e.g., in the reaction of copper ethyl acetoacetate derivatives with glycols ... 

The volatile hydrogen cyanide produced under these circumstances may be detected by the color reaction described on page 348 using copper ethyl-acetoacetate and tetrabase. 

In contrast to mercury cyanide, alkali cyanides are completely converted into alkaK cyanates when warmed with an excess of potassium permanganate with the precipitation of MnOg. The latter and the excess of KMn04 are destroyed by the addition of a drop of hydroxylamine hydrochloride and a drop of 2 iV hydrochloric acid. At this stage, Hg(CN)2 releases hydrogen cyanide which can be detected by the copper ethyl acetoacetate-tetrabase test described on page 348. In this way, starting with a drop of the test solution, 2 y of Hg(CN)2 can be detected in the presence of 500 y of alkali cyanide. 

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. 

Bromination of Beta Keto Esters. The work of K. A. Pedersen on the bromination of beta keto esters in the presence of copper(II) and other divalent metal ions provides several examples of reactions proceeding via complexes (29), The complexes provide an alternative and much more rapid route for the bromination reaction. These reactions are accelerated by bases which take up a proton from the beta keto esters. For such substrates, e.g. ethyl acetoacetate, the general expression for the pseudo first order rate constant in the presence of copper has the form ... 

Compound Name Copper Acetate Dimethylacetamide Ethyl Acetate Isobutyl Acetate Isopropyl Acetate Methyl Acetate Nickel Acetate n-Propyl Acetate Sec-Butyl Acetate Zinc Acetate Acetaldehyde Acetic Anhydride Ethyl Acetate Ethyl Acetate Ethyl Acetoacetate Ethyl Acetoacetate Acetone... 

Heating chloroacrolein yields 20% of 6-chloro-2-formyl-4//-pyran.l92The formation of pyrans by thermal decomposition of ethyl acetoacetate and its homologs on a copper powder catalyst is patented.193 Surprisingly, 2H-pyran 148 (20%) was reported when 2-oxoglutaric acid reacted with lead(II) nitrate.194... 

A MiXTbire of 12 g. (0.50 gram atom) of magnesium turnings, 130 g. (1.0 mole) of ethyl acetoacetate, 200 g. of benzene (dried over sodium), and 120 g. (1.50 moles) of acetyl chloride is heated under reflux for two hours in a i-l. round-bottomed flask provided with a condenser closed by a calcium chloride tube and supported in an oil bath (85-90°) (Note 1). The yellow reaction mixture is cooled in an ice bath, and the liquid portion decanted into a separatory funnel. The residue in the flask is washed twice with 50-cc. portions of ether, and the ethereal solution poured over ice. The ether-water mixture is then added to the benzene solution in the separatory funnel, and the mixture is shaken thoroughly (Note 2) the aqueous layer is drawn off and discarded. The benzene-ether solution is washed once with 500 cc. of 5 per cent sodium bicarbonate solution, once with 50 cc. of water, and finally dried over calcium chloride. The ether and most of the benzene are removed by distillation from a water bath, and the remainder of the benzene is driven off at 50°/5o mm. The ethyl diacetylacetate is then precipitated from the residue as copper derivative by the addition of 1200 cc. of a saturated aqueous solution of copper acetate (Note 3). After addition of the copper acetate solution, the contents of the flask are shaken vigorously now and then and allowed to stand for an hour to ensure complete precipitation of the copper derivative. The blue copper derivative is filtered on a Buchner funnel, washed with two 50-cc. portions of water, and transferred directly to a separatory funnel where it is mixed with 600 cc. of ether. 

To the reaction mixture 450 g. of zinc dust (Note 2) is added in portions of about 10 g. with vigorous stirring. The rate of addition is regulated so that the temperature never rises above 6o°. After the addition is complete (Note 3), the mixture is refluxed for two to three hours on a hot plate until the unreacted zinc dust collects in balls. The hot solution is then poured through a fine copper sieve, with stirring, into 30 1. of ice water. The crude product which separates is contaminated with zinc (Note 4). On recrystallization from 1500 cc. of 95 per cent ethyl alcohol, 360-390 g. of 2,4-dimethyl-3-acetyl-5-carbethoxypyrrole (m.p. 143-1440) is obtained (55-60 per cent of the theoretical amount based on the ethyl acetoacetate used) (Note 5). A second recrystallization may be necessary to secure a perfectly white product, but the product of the first recrystallization is sufficiently pure for conversion to kryptopyrrole. 

Copper derivative. Shake 0.2 g of the substance vigorously with a little cold, saturated, aqueous copper(n) acetate solution. Many ends give a solid, green or blue, copper derivative, which can be crystallised from ethanol and often has a definite m.p. (e.g. from ethyl acetoacetate, m.p. 192 °C from diethyl acetonedi-carboxylate, m.p. 142 °C. 

Over Ni-kieselguhr (eq. 5.35, A),121 copper-chromium oxide (eq. 5.35, B)7 and Raney Ni (eq. 5.35, C)122 in ethanol, ethyl acetoacetate is hydrogenated quantitatively to ethyl 3-hydroxybutyrate under the conditions described in eq. 5.35. 

Ethyl acetoacetate, 20, 26 21, 23, 46,67 Ethyl acrylate, 20, 36 Ethyl alcohol, anhydrous, 22, 59 Ethyl benzoate, 20, 32 Ethyl bromide, 22, 59 Ethyl bromoacetate, 21, 51 Ethyl a-bromoisobutyrate, 21, 53 Ethyl /3-bromopropionate, 20, 6S Ethyl caprylate, 20, 69 Ethyl chlorocarbonate, 21, 81 2-Ethylchromone, 21, 42 Ethyl diacetylacetate, 21, 46 COPPER DERIVATIVE, 21, 45 Ethyl a,a-DIMETHYL-/3-PHENYL-/3-HY-DROXYPROPIONATE, 21, S3 Ethylene chloride, 20, 28 22, 76 Ethyl 1,16-hexadecanedicarboxy-late, 21, 48... 

Copper (II) chloride proved to be a very efficient catalyst for the Biginelli reaction in the absence of solvent [27]. When ethyl acetoacetate, aldehydes and urea or thiourea were heated neat in the presence of copper (11) chloride, the Biginelli products were isolated, after recrystallization from hot ethanol, in high yields and purities (Scheme 7). 

Reactions of 2,4-pentanedione or ethyl acetoacetate with ethene in the presence of manganese(III) acetate and copper(II) acetate in an autoclave under 50 atm at 60 °C give a mixture of 443 and 444 (equation 150). This reaction involves an oxidative 1,3-cyclization of alkyl radicals . 

Freshly distilled a-naphthylamine added at 160 with vigorous stirring to ethyl acetoacetate and a little Gu-acetate, after 15 min. at 160 the mixture is left overnight, then the excess of ester removed under reduced pressure —acetoacet-a-naphthalide. Y 70% (p. 1292).— Without copper and with a very pure starting material the yield fell to zero (p. 1287). (A. Albert, D. J. Brown, and H. Duewell, Soc. 1948, 1284.)... 

The first synthesis modelled on biomimetic lines was directed to obtaining anacardic acids by way of polyketides [237] and later to a (17 l)-orsellinic acid [43]. A less complicated approach based on the Michael addition of ethyl acetoacetate and ethyl octadec-2-enoate, has led to a C15 orsellinic acid, Fig (4)-56, 2,4-dihydroxy-6n-pentadecylbenzoic, considered to be the biogenetic precursor of the cashew phenols [238], notably cardol, by decarboxylation. The use of bromine at the aromatisation stage in this synthesis precluded the extension of the method to components with unsaturated side-chains, although bromination with copper(ii)bromide and thermal debromination offers an alternative procedure. In a more recent approach, by the use of an oxazole intermediate and its addition to ethyl acetoacetate, (15 0) and (15 1) anacardic acid have been obtained [239] as shown in Scheme 5a, b. The 8(Z),1 l(Z)-diene and 8(Z),1 l(Z),14-triene have also been synthesised [240] by way of ethyl 6-(7-formylheptyl)-2-methoxybenzoate (C), prepared from acyclic sources, rather than, as in previous work, by semisynthesis from the ozonisation of urushiol. 

Some mercuric chloride added all at once at 100° to a mixture of benzalde-hyde, ethyl a-bromoadipate, Zn-powder, and some copper(ll) ethyl acetone etate in anhydrous benzene-toluene, the violent reaction starting after 1-2 min. cooled if necessary, and refluxed 0.5 hr. after the reaction has subsided ethyl a-(a-hydroxybenzyl) adipate. Y 60%.— Both mercuric chloride and copper (II) ethyl acetoacetate serve to activate the Zn-powder. F. e. s. R. and S.G lin, C.r. 255, 1400 (1962). 

However, the formation of the pyrroles 234 by copper(II)-catalyzed reaction of alkenyl azides 229 with ethyl acetoacetate was explained by an attack of the enolate 231 at the jS-carbon atom of the polarized C,C double bond of intermediate 230 (Scheme 5.29). The proposed mechanism included ring closure by a second nucleophilic attack followed by hydrolysis, dehydration, and tautomerism to get the aromatic final product 234. 

A 10%-soln. of pentane-2,4-dione copper complex in chloroform shaken 12-24 hrs. at room temp, with a 10%-soln. of m-nitrobenzoyl chloride in the same solvent, and the crude intermediate triketone heated 10-15 min. with aq. 3 N NHg l-m-nitrophenylbutane-l,3-dione. Y 92%.—The method is simple, gives good yields of pure products, and is the most convenient one for the prepn. of certain / -diketones. F. e., also deacetylation of the triketones with ethanolic 30%-H2S04, and condensations with ethyl acetoacetate copper complex, s. W. J. Barry, Soc. 1960, 670. 

Chiba and coworkers developed a Cu(NTf2)2-catalyzed synthesis of pyrroles from a-ethoxycarbonyl vinyl azides and ethyl acetoacetate through the 1,4-addition reaction of the acetoacetate to the vinyl azides [19]. Jiao and coworkers reported a copper- or nickel-catalyzed highly selective denitrogenative annula-tion of vinyl azides with acetaldehydes to 2,4- and 3,4-diaryl-substituted pyrroles. Cu(OAc)2 could catalyze the formation of 2,4-diaryl-substituted pyrroles. This selective polysubstituted pyrrole synthesis could proceed under mild conditions without any acidic or basic conditions [20] (Scheme 8.8). 

However, over Ni-kieselguhr in the absence of solvent or in ether and methylcyclo-hexane 32-33% of a diester, ethyl 3-(3 -hydroxybutyryloxy)butyrate (8), was produced along with 68-67% of ethyl 3-hydroxybutyrate and small quantities of dehydroacetic acid, and over copper-chromium oxide 16% of the diester and 7% of dehydroacetic acid were formed in the absence of solvent. It was suggested that the diester is formed through the hydrogenation of the intermediate 9, which results from 2 mol of acetoacetic ester with elimination of 1 mol of ethanol and that the condensation reaction is reversible (Scheme 5.6). Hence, the formation of the diester is depressed in the hydrogenation in ethanol.121 The reaction pathway in Scheme 5.6 has... 

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