Estudio de la formación de complejos de la 4,5-diamino 3-metil-2,6-dioxo-1,2,3,6,-tetrahidropirimidina con cationes divalentes de la primera serie de transición

Se investiga la formación de complejos en disolución acuosa y medio hidroetanólico, del clorhidrato de la 4,S-diamino-3-metil-2,6-dioxo- 1, 2; 3, 6, tertahidropirimidina (LH2Cl) con cationes divalentes de la primera serie de transición por métodos potenciométricos conductimétricos y espectrofotométricos. Los datos potenciométricos o espectrofotométricos permiten determinar las constantes estequiométricas globales de formación de complejos con relaciones metal/ligando 1/ 1, 1/2 Y 1/3 a 2S.00±0.OS oC, 1=0. 1 M(KCl) y en atmósfera inerte (N2). De la mezcla Cu (I1)-LH2 Cl se aisla un sólido verde de aspecto rnicrocristalino. La caracterización de este compuesto por análisis elemental, espectroscopia IR, análisis térmico (TG, ATD), Y medidas magnéticas conduce a la fórmula CuLC12 *6H2.The formation of the complexes in aqueous solution and ethanolic medium, between the 4,S-diamine-3-methyl-2,6-dioxo- 1, 2, 3, 6-tetrahydropyrirnidine hydrochloride and sorne bivalent ions of the rust row transitions elments, has been investigated by potentiometric, conductometric and spectrofotometric methods. The potentiometric or spectrofotometric data, allow to obtain the overall stoechiometric stability constants for :¡everal complexes with metal/ligand ratios 11 1 .. 1/2 and 1/3 at 2S.00±0.OS oC, 1=0. 1 M(KC1) in inert atmosphere (N2). From the Cu-LH2 Cl we have isolated a microcristaline green solido Ihe characterisation of this material by elemental analysis, IR spectroscopy, thermal analysis (TG, DTA) and magnetic measurements given the formula CuLC12*6H20

Degradación del 4,5-diamino-2,6-dioxo-3-metil-1,2,3,6-tetrahidropirimidina en disolución acuosa

The cinetic of the degradation process of the 4,5-diamine-2,6-dioxo-3-methyl-1,2,3,6-tetrahidropyrimidine has been studied in aqueous solution. The fmal product of the degradation process has been characterized by means of chemical analysis, espectrofotometry of mass, IR, NMR, suggests that tite formula corresponds to 1,6-dimethyl-2,4,7,9- tetrahidroxypyrimido-4,5, h pteridine.Se ha estudiado la cinética del proceso de degradación del 4,5-diamino-2,6-dioxo-3-metil-1,2,3,6-tetrahidropirimidina en disolución acuosa. El producto final del proceso de degradación se ha caracterizado mediante análisis químico, espectrofotometría de masas, IR y RMN, sugiriendo se para el, la fórmula correspondiente al 1 ,6-dimetil-2,4, 7 ,9-tetrahidroxipirimidina4,5, h-pteridina

Estudio en disolución de los complejos de la 4,5-diamino-3-metil-2,6-dioxo-1,2,3,6-tetrahidropirimidina con Fe(III) y Cr(III)

Se determina la estequiometría de los complejos formados por reacción del clorhidrato de la 4,5-diamino-3-metil-2,6-dioxo-1, 2, 3, 6-tetrahidropirimidina (LH2 Cl) con FeCl3 y CrCl3 por métodos potenciométricos, conductimétricos y espectrofotométricos. La banda de absorción del complejo FeL3 (λ=510 nm.) permite determinar el orden y la entalpía de activación del proceso de su formación.The stoichiometry of the complexes formed by reaction of 4,5-diamino-3- methyl-2,6-dioxo-1, 2, 3, 6-tetrahydropyrimidine hydrochloride (LH2 Cl) with FeC13 or CrC13 has been investigated by potentiometric, conductimetric and spectrofotometric methods. An absorcion band of FeL3 complex ( A =510 nm.) allow to obtain the order and activation enthalpy of the reaction

Complejos de cefalexina con cationes de elementos del cuarto periodo. I.-Estudio en disolución acuosa

The formation of the complexes, in aqueous solution, between the cephalexin and sorne ious of the fourth period elements has been investigated by potentiometric and spectrophotometric methods. The stability constants has been determinated.Se ha investigado la formación de complejos, en disolución acuosa, de cefalexina [ácido 7-(D-2-amino-2-fenil-acetamido )-3-metil-8-oxo-S-tia-1-azabiciclo [4.2.O] oct-2-eno-2-carboxilico] con cationes de elementos del cuarto período, por métodos potenciométricos y espectrofotométricos. Se han determinado asímismo las constantes de formación de complejos

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A partir de los espectros de absorción en la zona del ultravioleta e I. R., así como del espectro de R. M, N. se ha determinado la estructura más probable para la molécula de 4,5-diamino-1,6-dihidro-1-metil-2-metiltio-6-oxo-pirimidina. Asimismo, se ha estudiado la estabilidad térmica de esta sustancia a partir de los diagramas de A. T. D. Y T. G. Por último, se ha determinado el valor de su constante ácida, que es del orden de 10-12.From the absorption spectra in the ultraviolet and infrarred regions, and from the MNR spectrum, the most probable molecular structure of the 4,5-diamino-1,6-dihidro-1-methyl-2-methylthio-6-oxo-pyrimidine has been determined. The thermal stability of this substance has been studied from the D. T. A. and T. G. diagrams. The apparent acid constant of the mentioned substance has also been calculated

Treatment of Activated Carbon with HO. Effect on the Porous Texture

The effect of the oxidation of activated carbon (AC) with aqueous solutions of H 2 O 2 on the porous texture of the material has been investigated. In such treatments of AC, H 2 O 2 solutions of varying concentration and pH (i.e., unchanged pH and pH values of 2.5 and 11.5) were used. Oxidizing solutions containing Fe 2+ , Fe 3+ , ethanol or ether were also employed. Initial outgassing of AC and contact of the intermediate product with the oxidizing solution were effected under controlled conditions of temperature and time. The resulting samples were characterized texturally by gas adsorption (N 2 , 77 K) and mercury porosimetry. The mass of sample significantly increased when H 2 O 2 solutions at pH 2.5 were used. Such treatment of AC produced a loss of microporosity or none depending on the method of preparation of the samples. Thus, a loss of microporosity occurred, for example, when contact between the H 2 O 2 solution and the AC was effected at 0°C, whereas no loss of microporosity occurred when the temperature was 70°C. For a few samples the unfavourable effect of oxidation of the AC on its porous texture not only concerned the micropores but also the mesopores and macropores