5,5—Diethylbarbituric acid

The condensation of 1 mol of ethyl malonate with two mols of ethyl iodide in the presence of two mols of sodium ethoxide gives a good yield of ethyl diethylraalonate. Upon allowing the latter to react with the theoretical quantity of urea in the presence of an alcoholic solution of sodium ethoxide, veronal (diethylbarbituric acid or diethylmalonylurea) is produced. 

Diethylbarbituric acid. In a dry 250 ml. distilling flask, fitted with a thermometer reaching to within 3-4 cm. of the bottom and a condenser, place 51 g. of clean sodium and add 110 g. (140 ml.) of super-dr ethyl alcohol (Section 11,47,5). When all the sodium has reacted, introduce 20 g. of ethyl diethylmalonate and 7 0 g. of dry imea (dried at 60 for 4 hours). Heat the flask in an oil bath and slowly distil off the ethyl alcohol. As soon as the temperature of the liquid reaches 110-115°, adjust the flame beneath the bath so that the contents of the flask are maintained at this temperature for at least 4 hours. Allow the flask to cool somewhat, add 100 ml. of water and warm until the solid (veronal-sodium) dissolves. Pour the solution into a beaker, and add a further 100 ml. of water but containing 7 0 ml. of concentrated siilplmric acid this will hberate the veronal from the sodium derivative. The veronal usually crystallises out if it does not, add a few more drops of dilute sulphuric acid until the solution is acid to Congo red. Heat the contents of the beaker, with stirring and the addition of more water if necessary, until all the veronal dissolves at the boiling point. Allow the hot solution to cool, filter off the crystals of veronal and diy in the air. The yield is 12 g., m.p. 190°. 

The structure of barbituric acid was the subject of disagreement for many years, but since 195 2 (52BSB44) the trioxo formulation (57 R = H) has been accepted generally, along with the fact that barbituric acid loses a proton, first from carbon (anion) and subsequently from nitrogen (dianion). Barbital (5,5-diethylbarbituric acid) adopts a similar trioxo form (57 R = Et) (69AX(B)1978). 

To be distinguished from Malonurea , a trade name ( ) once widely used for 5,5-diethylbarbituric acid (barbital). 

Diethylbarbituric acid (Barbital) [57-44-3] M Crystd from water or EtOH. Dried in a vacuum over P2O5. 

A mixture of 6.008 g of citric acid, 3.893 g of potassium dihydrogenphosphate, 1.769 g of boric acid, and 5.266 g of pure diethylbarbituric acid is dissolved in water and made up to 1 L. The pH values at 18°C of mixtures of 100 mL of this solution with various volumes (20 of 0.2M sodium hydroxide solution (free from carbonate) are tabulated below. 

Buffer solution Britton and Robinson type of buffer solution is made of 28.6mM of each chemical as follows citrate acid, KH2P04, H3BC)3, and diethylbarbituric acid that can be monitored into a wide spectrum of pH values ranging from pH 2.0 to 12.0. The optimal pH value for RNA extraction is pH 7.4. For protein extraction, a Tris-HCl buffer containing 2% SDS at pH 7 or pH 9 is optimal heating retrieval solution. 

Under solid-liquid PTC conditions 5,5-diethylbarbituric acid was N,N-dialkylated in a good yield in the presence of a lipophilic ammonium salts and potassium carbonate when reaction mixtures were irradiated in a household microwave oven (Eq. 26). 

Barbital (diethylbarbituric acid, Veronal) HEPPS (EPPS. 4-(2-hydroxyethyl)-l-piperazin-propanesulfonic acid)... 

Problem 16.55 Barbiturates are sedative-hypnotic varieties of 5,5-dialkyl substituted barbituric acids. Write the reaction for the formation of Veronal (5,5-diethylbarbituric acid) from the condensation of urea with diethylmalonic ester. [See Problem 17.13(a)]. ... 

Diethylbarbituric acid, A002 Diethyl benzoyl phosphonate, AT83 Diethyl ci s-bromobutenedioate. 

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