Ethyl oxomalonate

The liquid is left in the freezing mixture for several hours, then gradually allowed to come to room temperature (Note 2). Red gases are slowly evolved. After standing for two days or more at room temperature, the liquid is transferred to a distilling flask provided with a capillary air intake, and the delivery tube connected with a water-cooled condenser and receiver. The distillation is performed under diminished pressure, by the use of a water pump. Considerable nitric oxide is evolved before the pressure drops to about 70 mm. (Note 3). 

The first fraction consists mainly of water, a little ethyl acetate, and some ethyl oxomalonate which recombines with the water to form ethyl mesoxalate. When the pressure has dropped to 45 mm. and the temperature has risen to 1 xo°, the receiver is 

The yield of ethyl oxomalonate is decreased if the nitrous anhydride is not dried. 

If the temperature is raised too rapidly, the liberation of gases causes the mixture to boil too vigorously. 

A motor pump is not recommended because the nitric oxide is apt to cause corrosion. If too high a vacuum is used at first, a residue of ethyl iso-nitrosomalonate may remain. 

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Ethyl Oxomalonate, 4,27 Ethyl Phenylacetate, 2, 27 Ethyl Propane-i, i, 2, 3-tetracar-boxylate, 4, 20, 77 Ethyl succinate, 6, 10 Ethyl sulfate, 4, 60... 

Upon adding the calculated amount of water to ethyl oxomalonate, decolorization takes place immediately with evolution of heat, and on cooling a solid mass of ethyl dihydroxy-malonate results. After recrystallization from chloroform the product melts at 56-57°. (Communicated by Elizabeth Gilman and T. B. Johnson.)... 

A. Ethyl 2,5-dimethylphenylkydroxymalonate. One hundred and seventy-four grams (1 mole) of ethyl oxomalonate (Note 1) and 265 g. (2.5 moles) of J>-xylene are mixed in a 1-1. threenecked flask equipped with a good stirrer, a dropping funnel, and a calcium chloride drying tube. Suitable precautions are taken to exclude moisture from the reaction mixture. While the mixture is cooled in an ice-water bath and stirred vigorously, 325 g. 

The ethyl oxomalonate must be of good quality. It has been found possible to use nitrogen peroxide (now available in cylinders from the du Pont Company) in the preparation of this reagent. The general conditions are the same as in the previous method in Organic Syntheses 1 except that the generating flask... 

The remainder of the distillation must be conducted with extreme care. As soon as the ethyl oxomalonate has partly distilled over and the temperature has risen somewhat, the remaining iso-nitroso compound begins to decompose and sometimes liberates gases so rapidly that the thermometer and capillary tube may be blown out of the flask. If the manometer is watched closely, and at the first sign of liberation of gas, as evinced by a sudden increase in pressure, a wet towel is placed around the flask, the reaction can be slowed down. 

Ethyl oxomalonate is obtained from a variety of intermediates 1 but the only method which appears of practical value consists in the oxidation of ethyl malonate by means of oxides of nitrogen. This reaction, carried out in two steps by Bouveault and Wahl,2 was studied by Schmidt 3 and subsequently considerably improved by Curtiss 4 and also by Meyer/ ... 

Bromomandelic acid has been prepared by the bromination of -bromoacetophenone followed by alkaline hydrolysis 3 by the alkaline hydrolysis of the product formed by the addition of chloral to -bromophenylmagnesium bromide 4 and by the condensation of bromobenzene and ethyl oxomalonate in the presence of stannic chloride followed by hydrolysis and decarboxylation.5 />-Bromomandelic acid is a valuable reagent in the analyses of zirconium and hafnium.6... 

Ethyl Oxomalonate (Coll. Vol. i, 261) Oxidation of ethyl malonate with... 

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