Thermochemical study of 5-methyluracil, 6-methyluracil, and 5-nitrouracil

The standard (p° = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, at T = 298.15 K, for 5-methyluracil, 6-methyluracil, and 5-nitrouracil were derived from the values of the standard massic energies of combustion measured by static bomb combustion calorimetry. The results obtained together with literature values of the enthalpies of sublimation yielded the standard molar enthalpies of formation, in gaseous phase, at T = 298.15 K. These values are discussed in the terms of structural enthalpic increments.     

Thermochemical study of 5-methyluracil, 6-methyluracil,and 5-nitrouracil

The standard (p° = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, at T = 298.15 K, for 5-methyluracil, 6-methyluracil, and 5-nitrouracil were derived from the values of the standard massic energies of combustion measured by static bomb combustion calorimetry. The results obtained together with literature values of the enthalpies of sublimation yielded the standard molar enthalpies of formation, in gaseous phase, at T = 298.15 K. These values are discussed in the terms of structural enthalpic increments.     

蛋氨酸合成酶催化反应研究VII.5-氨基-6-甲基尿嘧啶的合成研究

报道了5-氨基-6-甲基尿嘧啶简便的合成方法。该化合物以6-甲基尿嘧啶（2） 为起始物，经硝化或重氮化分别得到了中间体5-硝基-6-甲基尿嘧啶（3）和5-偶氮 苯基-6-甲基尿嘧啶(4)，化合物3和4经Na_S_2O_4还原，合成产物5-氨基-6-甲基尿 嘧啶（1）。     

蛋氨酸合成酶催化反应研究 VII.5-氨基-6-甲基尿嘧啶的合成研究

报道了 5 氨基 6 甲基尿嘧啶简便的合成方法 .该化合物以 6 甲基尿嘧啶 ( 2 )为起始物 ,经硝化或重氮化分别得到中间体 5 硝基 6 甲基尿嘧啶 ( 3 )和 5 偶氮苯基 6 甲基尿嘧啶 ( 4 ) ,化合物 3和 4经Na2 S2 O4还原 ,合成产物 5 氨基 6 甲基尿嘧啶 ( 1) .     

A new synthesis of 5-hydroxy-6-methyluracil

Dehydration of 5,6-dihydro-5,6-dihydroxy-6-methyl- and 5,6-dihydro-5,6-dihydroxy-1,3,6-trimethyl-uracil in 0.4 M aqueous sulfuric acid gives 5-hydroxy-6-methyl- and 5-hydroxy-1,3,6-trimethyluracil in quantitative yields. Two possible mechanisms have been examined using the mPW1k/6-311+G(2df,2pd)//mPW1k/6-31+G(d,p) method for the transformation of methylated and non-methylated 5,6-dihydro-5,6-dihydroxy-6-methyluracils into the corresponding 5-hydroxy-6-methyluracils. The first is a hydride C5-C6 shift occurring in concert with the loss of a water molecule and formation of the corresponding protonated 5,6-dihydro-5-oxo-6-methyluracils. The second is an acid-catalyzed dehydration reaction to yield 5-hydroxy-6-methyluracils. The calculations demonstrated that the second pathway was energetically most favorable.     

The Benzoylation of 6-Methyluracil and 5-Nitro-6-methyluracil

6-Methyluracil and 5-nitro-6-methyluracil react with variable molar quantities of benzoyl chloride in acetonitrile-pyridine at room temperature to give I-N, 3-N-dibenzoyl-6-methyluracil 3b and l-N-benzoyl-5-nitro-6-methyluracil 4b. The reactive rates of debenzoylation of 3b and 4b were investigated.     

Synthesis and characterization of 5-bromo-3-sec-butyl-6-methyluracil

A new synthetic method for 5-bromo-3-sec-butyl-6-methyluracil (Bromacil) using 2-bromobutane and urea as starting materials is described. The synthesis involved condensation, cyclization and bromination with a total yield of 60%. The structure of Bromacil was determined by ¹H NMR, ¹³C NMR and IR spectroscopy. __________ Translated from Journal of Shandong University (Natural Science Edition), 2007, 42(7): 9–12 [译自: 山东大学学报(自然科学版)]     

Preparation and Structure Characterization of 4-Amino-1,2,4-triazol-5-one Hydrate

4-Amino-1,2,4-triazol-5-one hydrate (ATO·H₂O) was prepared and its structure was analyzed by four-circle diffraction measurement. The obtained results show that the crystal belongs to the triclinic crystal system, space group P 1 with crystal parameters a = 6.432(1), b = 6.551(1), c = 6.740(1) ; = 68.04(1), = 82.18(1), = 81.90(1)°, V = 259.7(7) ³; Z = 2; Dc = 1.510 g/cm³; = 0.131 mm^-1; F(000) = 124. ATO·H₂O was characterized by FT-IR analysis, X-ray diffraction analysis, and single crystal diffraction analysis.     

Oxidation of 5-Hydroxy-6-methyluracil in Alkaline Aqueous Solutions

Russian Journal of General Chemistry - 5-Hydroxy-6-methyluracil was found to be oxidized by molecular oxygen in an alkaline aqueous solution. The effect of temperature, concentration of alkali and...     

5-Hydroxy-6-methyluracil as an efficient scavenger of peroxy radicals

The reaction of 5-hydroxy-6-methyluracil with peroxy radicals generated by the thermal decomposition of azodiisobutyronitrile was studied at 75 °C in ethanol, propan-2-ol, and dimethyl sulfoxide. The stoichiometry of the reaction is 1: 1. The reaction product is dihydro-6-hydroxy-6-methylpyrimidine-2,4,5-trione in an anhydrous solvent or dihydro-5,5,6-trihy-droxy-6-methylpyrimidine-2,4-dione in the presence of water. The rate constant for the reaction of 5-hydroxy-6-methyluracil with the peroxy radicals is ∼10⁸ L mol⁻¹ s⁻¹.     

2-Mercapto-6-methyluracil derivatives

Conclusions The reaction of the sodium salts of 2-mercapto-6-methyluracil and some 2-mercaptopyrimidines with chlorohydrins, 1,4-dibromobutane, and 1-bromo-2-fluoroethane was studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1841–1846, August, 1968.     

Synthesis of 9-Aryl-6-aminopurines from 5-Amino-1-aryl-1H-imidazole-4-carbonitriles

5-Amino-1-aryl-1H-imidazole-4-carbonitriles were converted into 9-aryl-6-aminopurines viaimidates formation at treating with CH(OEt)₃, Ac₂O followed by reaction with ammonia.     

Derivatives of 2-mercapto-6-methyluracil

The reaction of the sodium salt of 2-mercapto-6-methyluracil with , -dibromoalkanes Br(CH₂)Br (n=1,4,5,6) has given the corresponding , -bis(4-hydroxy-6-methyl-2-pyrimidinylthio) alkanes. The reaction of the same salt with 1,2-dibromoethane gave 7-methyl-5-oxo-2,3,4,5-tetrahydrothiazolo[3,2-a]pyrimidine and 5-methyl-7-oxo-2,3,4,7-tetrahydrothiazolo[3,2-a]pyrimidine, and its reaction with 1,3-dibromopropane led to 8-methyl-6-oxo-3,4,5,6-tetrahydro-2H-pyrimidino[2,1-b]-1,3-thiazine.     

6-Amino-5-cyano-1H,4H-pyrazolo[3,4-b]pyrans

The reaction of 3-methyl-1-phenyl-5-pyrazolene with arylideneamino nitriles in alcohol leads to the formation of 3-methyl-4(1-aryl-2,2-dicyanoethyl)-5-pyrazolones, which are readily cyclized in the presence of bases to the corresponding 6-amino-5-cyano-3-methyl-4-aryl- 1H,4H-pyrazolo[3,4-b]pyrans. The structures of the intermediate and final products were confirmed by the IR, UV, PMR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 801–806, June, 1982.