Interactions of xanthines with activated carbon: II. The adsorption equilibrium

In the present work, we have studied the adsorption of xanthine derivatives by activated carbon sorbents in aqueous solutions. The study comprised both kinetic, equilibrium and thermodynamic aspects. The kinetic results were reported in a previous paper; the equilibrium-related results are discussed here. The two types of carbon used exhibit some differences but the equilibrium isotherms obtained are all of the H-3 type in the classification of Giles. This suggests a high affinity of the sorbents for the sorbates. We also found that the overall adsorption process comprises more than one individual adsorption-desorption process of which one leads to the formation of a “monolayer” and the other to the “precipitation” of the sorbate on the sorbent surface (multilayer adsorption); the amount of sorbate adsorbed in monolayer form was seemingly greater in C-A14.     

Thermal behaviour of some 2-benzylamino-2-deoxyheptonic acids

The thermal behaviour of some 2-benzylamino-2-deoxyheptonic acids obtained from 2-benzylamino-2-deoxy-D-glycero-L-gluco, 2-benzylamino-2-deoxy-D-glycero-D-ido and 2-benzylamino-2-deoxy-D-glycero-D-taloheptononitriles (reported) previously has been studied in air (static atmosphere) and N₂ (dynamic atmosphere, flow rate 200 ml/min).

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Zusammenfassung Das thermische Verhalten einiger aus 2-Benzylamino-2-desoxy-D-glycero-L-gluco-, 2-Benzylamino-2-desoxy-D-glycero-D-ido und 2-Benzylamino-2-desoxy-D-glycero-D-talo-heplononitril (kürzlich beschrieben) erhaltenen 2-Benzylamino-2-desoxy-heptonsäuren wurde ín Luft (statische Atmosphäre) und N₂ (dynamische Atmosphäre, Strömungsgeschwindigkeit 200 ml/min) untersucht.

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( 200 /) 2--2- , 2--2---uepo-L, 2-2- ---- 2-2--- -- 2--2----ma .

     

Metal complexes of 6-chloropurine

Summary Five Cu(II), Pd(II), Cd(II), Pt(IV), and Au(III) complexes of 6-chloropurine have been obtained. The complexes were characterized by elemental analysis, IR,¹H-NMR and¹³C-NMR spectroscopy. On the basis of these data the structure of the complexes and the coordination of the ligand have been proposed. Thus, the physical and chemical methods supported evidence that in acidic medium, with exception of the Cu(II) complex, 6-chloropurine acts in the monoprotonated form neutralizing the charge of [PdCl₄]^2–, [CdCl₄]^2–, [AuCl₄]^– and [PtCl₆]^2– anions. The thermal behaviour of the complexes has also been studied.

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Metallkomplexe von 6-Chlorpurin

Zusammenfassung Es wurden fünf Komplexe von 6-Chlorpurin mit Cu(II), Pd(II), Cd(II), Pt(IV) und Au(III) erhalten. Die Komplexe wurden mittels Elementaranalysen, IR,¹H-NMR und¹³C-NMR charakterisiert. Auf der Basis dieser Daten wurde eine Komplexstruktur und eine bestimmte Koordination der Liganden vorgeschlagen. Physikalische und chemische Methoden beweisen, daß im sauren Bereich [mit der Ausnahme von Cu(II)] das 6-Chlorpurin in der monoprotonierten Form koordiniert, wobei die Ladung von [PdCl₄]^2–, [CdCl₄]^2–, [AuCl₄]^– und [PtCl₆]^2– jeweils neutralisiert wird. Das thermische Verhalten der Komplexe wurde ebenfalls untersucht.

     

Gasification in steam of a bituminous coal from Peñarroya (Cordoba,Spain) and of different samples prepared from it

The gasification with steam of a bituminous coal from Peñarroya (Cordoba, Spain) (H—O) and of several samples prepared from either by acid treatment (H—H, H—N, H—F and H—F(3)) or by thermal treatment (H—O—C) was studied under both dynamic and isothermal conditions (10 deg/min and 40 min at 1000°).It was found that only for the samples prepared by hydrofluoric acid treatment, H-F and H—F(3), did the gasification effected under such experimental conditions take place in a complete manner.

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Zusammenfassung Die Dampfvergasung von bituminöser Kohle (H—O) (Penarroya, Cordoba, Spanien) und von daraus durch Säurebehandlungen (H—H, H—N, H—F und H-F(3)) oder thermische Behandlung (H—O—C) hergestellten Proben wurde unter dynamischen und isothermen Bedingungen (10 °/min und 40 min bei 1000°) untersucht. Es wurde festgestellt, daß nur die durch Flußsäurebehandlung hergestellten Proben (H—F und H—F(3)) unter den experimentellen Bedingungen vollständig vergasbar sind.

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(10°/ 40 1000°) () , . , , , .

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The authors are grateful to the CAICYT of Spain for the financial support on Project No. 0794/82.     

Spectral and thermal studies of some 4-(O-acetyl)glycopyranosylaminopyrimidine derivatives

A spectral study (IR and UV spectroscopies) of seven 4-(O-acetyl)glycopyranosylaminopyrimidine derivatives has been carried out. The thermal study of the compounds allowed us to characterize the following processes: (i) desolvations, (ii) solid-solid transitions, (iii) melting, (iv) pyrolytic decompositions. Through the IR spectral study it was established that pyrolytic decompositions of all the compounds start with the acetyl groups. The reaction orders and activation energies of the deacetylation processes have been calculated.     

A new 2D cadmium chloride network with 2-aminopyrimidine displaying long lifetime photoluminescence emission

The hydrothermal reaction of CdCl₂ with 2-aminopyrimidine in water yields a 2D metal-organic coordination framework [CdCl₂(PymNH₂)] (1) (PymNH₂ = 2-aminopyrimidine). This compound consists of Cd₂(μ-Cl)₂ corner-sharing chains bridged by PymNH₂ through the endocyclic ring nitrogen atoms. Interestingly, this polymer exhibits long lifetime photoluminescence emission at room temperature in the solid state with long lifetimes decay.     

Interactions of xanthines with activated carbon: I. Kinetics of the adsorption process

Because of their pharmaceutical and industrial applications, we have studied the adsorption of xanthine derivates (caffeine and theophylline) by activated carbon. To this end, we examined kinetic, equilibrium and thermodynamic aspects of the process. This paper reports the kinetics results. The experimental results indicate that the process was first order in C and the overall process was assumed to involve a single, reversible adsorption-desorption process obeying a kinetic law postulated by us.     

Metal complexes of two 7-oxo-vic-triazolo[4,5-d]pyrimidine derivatives

Seven Hg(II), Pd(II), Cu(II), and Ag(I) complexes of two 7-oxo-vic-triazolo[4,5-d]pyrimidine derivatives have been obtained. The complexes were characterized by spectroscopic studies (IR,¹H-NMR and UV-visible) and magnetic measurements. On the basis of these data both the structure of the complexes and the coordination positions of the pyrimidinic ligands have been proposed. Likewise, the thermal behaviour of the complexes has also been studied.

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Metall-Komplexe von zwei 7-Oxo-vic-triazolo[4,5-d]pyrimidin-Derivaten

Zusammenfassung Sieben Hg(II)-, Pd(II)-, Cu(II)- und Ag(I)-Komplexe von zwei 7-Oxo-vic-triazolo[4,5-d]pyrimidin-Derivaten wurden hergestellt. Die Komplexe wurden durch die Daten der elementaren Analyse, spektroskopische Studien (IR,¹H-NMR und UV-Vis.) und magnetische Messungen charakterisiert. Auf der Basis dieser Daten wurden die Strukturen der Komplexe und die Koordinationsstelle der Pyrimidin-Liganden bestimmt. Das thermische Verhalten der Komplexe wurde ebenfalls untersucht.

     

Oxygen chemisorption by an anthracite from peñarroya (Spain). A comparative study using dynamic and isothermal gravimetric methods

The chemisorption of oxygen (P = 1 atm, flow rate, 200 ml min^?1) by an anthracite from Peñarroya and on other adsorbents prepared from the starting sample has been studied in isothermal and dynamic conditions using gravimetric methods.Hypotheses to justify the thermograms have been established and comparative information on the energetic aspects determining both gasification stages has been obtained.Some kinetic and thermodynamic aspects are studied from oxygen chemisorption isotherms.     

Thermal studies on lithium,sodium, potassium and ammonium monomethyl violurates

A study of the ammonium and some alkaline salts of monomethyl violuric acid by TG and DSC is described. These salts form hydrates in all cases and are, with some exceptions, very soluble in water.