Ethyl ethylenetetracarboxylate

A mixture of 200 g. (1.9 moles) of anhydrous sodium carbonate (Note 1) and 300 g. (1.25 moles) of ethyl bromomalonate (Org. Syn. 7, 34) is heated for three hours in a i-l. flask (Note 2) immersed in an oil bath at 150-160° (Note 3). After the heating period, 300 cc. of xylene (Note 4) is added while the contents of the flask are still hot (Note 5). The solid is broken up carefully with a rod and the mixture is transferred to a 2-1. beaker. The reaction flask is then rinsed with a mixture of 100 cc. of xylene and 100 cc. of water. This washing is poured into the 2-1. beaker and an additional 600 cc. of water is added. The solid readily dissolves upon stirring. The liquid mixture is transferred to a separatory funnel, shaken well, and allowed to settle (Note 6). The lower aqueous layer is discarded (Note 7). The xylene layer is transferred to a i-l. distilling flask and distilled until the temperature of the liquid itself is 170°. The liquid residue is then transferred to a 500-cc. Claisen flask and distilled under reduced pressure. The forerun up to i7o°/r5 mm. is discarded. The product is collected at 170-23o°/i5 mm. (Notes 8 and 9). The distillate solidifies within about fifteen minutes. The yield is 150-160 g. (75-80 per cent of the theoretical amount). 

The crude product is dissolved in 75 cc. of 95 per cent alcohol at a temperature of 40°, which is sufficient to insure complete solution. The alcoholic solution is cooled to 12° (Notes 10 and n) and filtered. The yield of air-dried, colorless product melting at 52.5-53.5° is 95-no g. (47-55 per cent of the theoretical amount). By evaporation of the alcohol, distillation of the residue under reduced pressure, and recrystallization of the solidified distillate, the yield may be increased to 110-115 g. (55-57 per cent of the theoretical amount), 

The sodium carbonate should be fine enough to pass through a roo-mesh sieve. 

The mixture is heated in an open flask. Due to the high boiling points of ethyl bromomalonate and ethyl ethyl-enetetracarboxylate, there is but little loss by volatilization. On the other hand, the yield is lowered by the use of a condenser, presumably because the water formed by the reaction is kept in the reaction mixture with resultant hydrolysis of one or both of the esters. 

The flask is placed in the cold bath. The three hours are counted from the time that the temperature of the bath reaches 

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The solubility of ethyl ethylenetetracarboxylate in 100 cc. of 95 per cent ethyl alcohol is as follows ... 

Ethyl ethylenetetracarboxylate has been prepared from monochloro- and monobromomalonic ester through removal of halogen acid with sodium,1 sodium ethylate,2 potassium acetate,3 potassium carbonate,4 sodium urethane, sodium formanilide and sodium acetanilide.6 It has also been prepared by treating the disodium derivative of ethyl ethane-1,1,2,2-tetracarboxylate with bromine,7 or iodine 8 by treating dibromomalonic ester with sodium,9 or sodium ethylate 10 and by treating the disodium derivative of malonic ester with iodine.11... 

Ethyl iec.-butylmalonate, 11, 22, 76, 77 Ethyl -butyrate, 13, 24 purification of, IS, 25 Ethyl carbonate, 11, 98 Ethyl chloroformatc, 12, 38 Ethyl cinnamate, 12, 36 Ethyl a,j3-mBROM o-p-PHENYLFROPio-nate, 12, 36, 37, 60 Ethyl dihydroxymalonate, 10, S7 Ethylene chlorohydrin, 12, 68 Ethylene dibromide, 10, g6 Ethyl ethoxyacetate, 13, 42 Ethyl ethylenetetracarboxylate, 11, 36... 

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