Dilituric acid

FIGURE 5 X-ray powder diffraction patterns for the alkaline earth cation derivatives of 5-nitro-barbituric acid (dilituric acid). The data were adapted from reference 47. 

Dilituric acid (5-nitrobarbituric acid) forms a sparingly soluble compound with potassium ions. The decrease in absorbance of the reagent gives a measure of the K content in the solution. Potassium ions can be precipitated by tetraphenylborate. The excess reagent forms an ion-pair with the cationic Cu(I)-neocuproine complex, and this ion-pair is extractable into methyl acetate. The absorbance of the extract is measured at 456 nm [83]. An indirect method involving the reaction of potassium tetraphenylborate with mercury(II) ehloranilate is very sensitive [84]. 

Additional work being conducted in pharmaceutical groups includes chemical microscopical characterization of dilituric acid and its complexes (77), characterization of the physicochemical properties of pharmaceuticals (78), and solid-state investigations incorporating hot-stage microspectroscopy (79,80). 

Thermogravimetric analysis played an important role during the characterization of the insoluble adducts formed by 5-nitrobarbituric acid (dilituric acid) with alkali metal (Group lA) and alkaline earth (Group IIA) cations [70]. This study was performed to understand the... 

Table 3 Thermogravimetric Analysis of the Adducts of Dilituric Acid with Group lA and IIA Cations [70]...

Nitrobarbituric acid (also named dilituric acid or 5-nitro-2,4,6-trihydroxypyrimidine), formally a cyclic urea derivative, is selected as a host component [25]. In the solid state 5-nitrobarbiturate has the tendency to form a dimer, and three kinds of possible linkage are designated as types A, B and C, as illustrated in Scheme 8.1. Among these. 

Dilituric Acid [5-Nitrobarbiluric acid, nilro-malonyJurea)... 

For identification—especially under the microscope—salts of amino acids with dilituric acid or picrolonic acid (92) or 2-nitroindane-l,3-dione (93 to 95) are used. 

Procedure Dilituric acid (200 mg) is dissolved in the necessary amount of hot water, and 100 ml of alanine are added to the solution. The mixture is boiled briefly and then allowed to cool slowly. The separated crystals are filtered off and washed twice with 1 ml of water. Yield, 0.2 mg. The melting point is not sharp. After crystallization from 7 ml of water 0.15 g of the product is obtained, which does not melt sharply. 

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