Ethyl acetoacetate purification

The Robinson annulation of ethyl acetoacetate and tra i -chalcone was investigated with pulverized NaOH in [BMIMjPFg as the base catalyst at 100°C 110). The mixture was neutralized before extraction with toluene. The product, 6-ethoxycarbonyl-3,5-diphenyl-2-cyclohexenone, was obtained by purification in a silica gel chromatography column. A yield of 48% was obtained (Scheme 7). The ionic liquid could be recycled and reused with no diminution of product yield. The C2 position in imidazolium cations is an acidic proton donor and may have reacted... 

Ethers, reactions of, 315, 671, 1067, 1068 see also under Aliphatic ethers and Aromatic ethers. p-Ethoxyphenylurea, 646 p-Ethoxyproptonitrile, 915,916 Ethyl acetate, 383 purificatioh of. 174 Ethyl acetoacetate, 475, 476, 477 keto-enol equilibrium of, 475, 1148 purification of, 478 reactions of, 478 ... 

Preparaton of the Enantiomers of Ethyl 3-Hydroxybutanoate. Reduction of ethyl acetoacetate with yeast yields ethyl (S)-3-hydroxybutanoate (15) as shown in Figure 4 (12-14). Purification of crude 15 as its crystalline 3,5-dinitrobenzoate gives (S)-15 of 100% e.e. (14,15). 

The following chemicals were obtained from the Aldrich Chemical Company, Inc., and were used without further purification p-acetamidoben2enesulfonyl chloride, 97% acetone, 99.9+%, HPLC grade sodium azide, 99% ethyl acetoacetate, 99% triethylamine, 99% rhodium(ll) acetate dimer phenylacetylene, 98%. The following solvents were obtained from Fisher Scientific and were used without further purification toluene, certified A. C. S. ethyl ether (Solvent grade. Concentrated) petroleum ether, certified A. C. S. Dichloromethane was distilled from calcium hydride. 

Novoldiamine. N ,N -Diethyl-1,4-penta nedia mine I -diethylamino-4-aminopentane 4-amino-I -diethylamino-pentane 2-amino-5-diethylammopentane 8-diethylamino-a -meth y Ibuty] amine 6 -diethyl aminoisopent ylamine. C -HjjNj mol wt 158.28. C 68.29%, H 14.01%, N 17.70%. Prepd commercially from 2-diethylaminoethano and ethyl acetoacetate. 2-ChlorOtriethylamine (formed hy the action of thionyl chloride on the alcohol) is condensed with the sodium derivative of ethyl acetoacetate to yield an Intermediate ester, which is hydrolyzed and decar boxylated to novo ketone (5 -diethylamino -2-pentanone). This is hydrogenated in the presence of ammonia to yield novoldiamine. Several other prepns, i.e, from 1,4-pentanediol and diethylamine Kyrides, U.S. pat. 2,365,825 (1944 to Monsanto). Purification procedure Jones, U.S. pat. 2,400,934 (1946 to Lilly). 

The copolymers were synthesized by radical initiated copolymerization of methacrylate monomers in butanone under inert conditions (dry nitrogen atmosphere). As initiator 2,2 -azobis-(2-methyl propionitrile) (AIBN) was employed. The copolymers obtained were used without further purification. The following example to produce the copolymer poly [methyl methacrylate-co-Zonyl TM-co-2-(methacryloyloxy)ethyl acetoacetate] (Table 1, polymer 21b) from three monomers illustrates the typical synthesis ... 

Benzotriazole, 20,16 Benzoylacetic ester, 23, 35 Benzoylation of acetoacetic ester by ethyl benzoate, 23, 35 Benzoyl chloride, 24, 14 purification of, 24, 15 Benzoyl Cyanide, 24,14, 16 Benzoyleormic acid, 24,16 Benzoyl-o-toluidines, conversion to indoles, 22, 95... 

When treated with concentrated alkali, acetoacetic ester is converted into two moles of sodium acetate, (a) Outline all steps in a likely mechanism for this reaction. (Hint See Sec. 21.11 and Problem 5.8, p. 170.) (b) Substituted acetoacetic esters also undergo this reaction. Outline the steps in a general synthetic route from acetoacetic ester to carboxylic acids, (c) Outline the steps in the synthesis of 2-hexanone via acetoacetic ester. What acids will be formed as by-products Outline a procedure for purification of the desired ketone. (Remember that the alkylation is carried out in alcohol that NaBr is formed that aqueous base is used for hydrolysis and that ethyl alcohol is a product of the hydrolysis.)... 

The use of ethyl [2-13C]acetoacetate instead of diethyl [2-t3CJmafonafe in the condensation reaction with 4H-pyran-4-one afforded ethyl 4-hydroxy[1 -13C]benzoate in 87% yield. In this case, 1.1 equiv of 4H-pyran-4-one and 1.1 equiv of potassium tert-butoxide were optimal. The addition of catalytic amounts of the base was not satisfactory. Ethyl [2-13C]acetoacetate was prepared from ethyl (2-13C]acetate as described for diethyl [2-13C]matonate.16 The maximum yield for this reaction on a 10-mmol scale was only 70% after distillation. 4H-Pyran-4-one reacted with nitromethane and potassium tert-butoxide (each 1.1 equiv) to afford 4-nitrophenol in 75% yield after purification by flash chromatography. This gives easy access to 4-nitro[4-13C]phenol. With 2,4-pentanedione, the condensation with 4H-pyran-4-one under the same reaction conditions gave 4-hydroxyacetophenone in 45-50% yield after purification. 

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