5-nitrobarbiturate

There are many synthetic routes to alloxan. Probably the best is direct oxidation of barbituric acid (1004 R = H) with chromium trioxide (5208(32)6) but it may be made from barbituric acid via its benzylidene derivative by direct or indirect oxidation of uric acid from 5-chlorobarbituric acid (1004 R = C1) by nitration or from 5-nitrobarbituric acid (1004 R = N02) by chlorination, both via the intermediate (1005) (64M1057) or by permanganate oxidation of uracil (1006) under carefully controlled conditions (73BSF1167). 

Methyl Benzoxazone 3,4-Methylenedioxy compounds (any) N-Methylmescaline N-Methyl Formamide Monoethanolamine 5-Nitrobarbituric Acid Nitroethane... 

The IR spectrum suggests that the compound exists partly in the enolic form, just like the anhydrous 5-nitrobarbituric acid 121). 

The fuels are, for example, 5-aminotetrazole, azodicarbonamide, -> Guanidine nitrate, -> Nitroguanidine, dicyandiamide, -> Triamino-guanidine nitrate and similar compounds, as well as salts of, for example, 5-nitrobarbituric acid, urea derivatives and also nitra-mines and similar compounds. The oxidisers are, for example, alkali or alkaline earth nitrates, -> Ammonium, alkali or alkaline earth perchlorates and metal oxides. 

Nitromalonic ester reacts with thiourea to yield 2-thio-5-nitrobarbituric acid (122) [Eq. (40)].117... 

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]. 

Anhydrous 5-nitrobarbituric acid (9) exists in the monohydroxy form (8a),27 but the trihydrate is in the aci-nitro form (9b)28 in the crystalline state as shown by X-ray analysis. IR and UV investigations29 and dipole moment measurements30 are consistent with those conclusions. The results of MO calculations show that the monohydroxy structure (9a) is the most stable. UV spectra31 as well as 14N-NQR data32 also support tautomer 9a in water. 

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... 

Hydrogen-Bonded Networks Constructed with 5-Nitrobarbiturate... 

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. 

Scheme 8.1 (a) Structural formula of the monoanion of 5-nitrobarbituric acid, (b) Type A... 

Two channels of different sizes exist in the crystal structure of inclusion complex 5 [25], As shown in Figure 8.11, two independent 5-nitrobarbiturate anions are linked in the para-to-para fashion by N-H- -O hydrogen bonds to form a dimer, and successive dimers related by the a translation associate in the ortho-to-ortho fashion to generate an approximately planar zigzag ribbon. 

Figure 8.11 Zigzag ribbon formed by 5-nitrobarbiturate ions and the hydrogen-bonded scheme in the thiourea-anion host lattice of 5, viewed along the b axis. The large spheres represent (CH3)4N+ ions. Symmetry transformation a(1 -yx, y, z)...

In this crystal structure, there is no intermolecular interaction between 5-nitrobarbiturate ions [25]. Figure 8.17 shows a portion of a hydrogen-bonded layer viewed along the a axis. 

Versatile roles of (thio)urea in the 5-nitrobarbiturate inclusion systems... 

---