Gas chromatographic study of donor-acceptor complexes I. Theoretical study

Summary New general equations have been derived to calculate, by gas-liquid chromatography, the equilibrium constants for complexing reactions between a volatile solute and a non-volatile reagent dissolved in a stationary liquid phase. These equations, which are more general than the relationships usually accepted, take into account the differences in molecular sizes between the inert solvent and the complexing reagent and the activity coefficients of the various species in solution. An equation relating the reaction enthalpy, the dissolution enthalpy of the solute in the liquid stationary phase and the composition of this phase, is also given.

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Gas-chromatographische Untersuchung von Donator-Akzeptor-Komplexen. I. Theoretische Untersuchung

Zusammenfassung Es wurden neue Gleichungen entwickelt, mit deren Hilfe durch Daten der Gas-Flüssig-Chromatographie die Gleichgewichtskonstanten bei der Komplexbildung zwischen einem flüchtigen Gelösten und einem nicht flüchtigen Reagens, die in einer flüssigen stationären Phase gelöst sind, berechnet werden können. Diese Gleichungen sind allgemeiner als die üblicheweise verwendeten Beziehungen und berücksichtigen die Unterschiede in den Molekülgrößen zwischen dem inerten Lösungsmittel und dem Komplexbildner-Reagens, sowie die Aktivitäts-Koeffizienten der verschiedenen Spezies in Lösung. Es wird ebenfalls eine Gleichung angegeben, die die Reaktionsenthalpie, die Lösungsenthalphie des Gelösten in der flüssigen stationären Phase und die Zusammensetzung dieser Phase in Beziehung setzt.

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Etude par chromatographie en phase gazeuse des complexes donneur-accepteur. I-Etude théorique

Résumé De nouvelles équations ont été développées pour calculer, par chromatographie gaz-liquide, les constantes d'équilibres de formation de complexes entre un soluté volatil et un réactif non volatil dissous dans la phase fixe. Ces équations sont plus générales que celles, plus simples, habituellement utilisées. Elles tiennent compte des différences de taille des molécules de solvant et d'agent complexant et des coefficients d'activité des espèces en solution. Une relation entre l'enthalpie de la réaction, l'enthalpie de dissolution du soluté dans la phase stationnaire liquide et la composition de cette phase est aussi donnée.

     

Electroanalytical study of fluvoxamine

Fluvoxamine (FVX) can be reduced at a mercury-drop electrode, with a maximum peak current intensity being obtained at a potential of –0.7 V vs. Ag/AgCl, in an aqueous electrolyte solution of pH 2. The compound was determined in a pharmaceutical product and in spiked human serum by square-wave adsorptive-stripping voltammetry (SWAdSV) after accumulation at the electrode surface, under batch conditions. Because the presence of dissolved oxygen did not interfere significantly with the analysis, it was also possible to determine FVX in the pharmaceutical product by use of a flow-injection analysis (FIA) system with SWAdSV detection. The methods developed were validated and successfully applied to the quantification of FVX in a pharmaceutical product. Recoveries between 76 and 89% were obtained in serum analysis. The FIA–SWAdSV method enabled analysis of up to 120 samples per hour at reduced cost, implying the possibility of competing with the chromatographic methods usually used for this analysis.     

噻唑硫磷的结构研究

噻唑硫磷(fosthiazate)是一种新型、高效的有机磷农药。它是由2-氧化噻唑烷与S-仲丁基-O-乙基硫代磷酰氯通过取代反应制得,其化学名为O-乙基-S-仲丁基-2-氧代-1,3-噻唑烷-3-基硫代膦酸酯,结构式如下：     

The study of benzimidazoles

The nature of the first two long-wave bands in the UV spectra of 2-substituted benzimidazoles has been analyzed on the basis of photoelectron spectra (PES). Three basic types of spectroscopic situations are typical of these compounds: 1) a change in the sequence of the occupied MO of the ground state does not influence the order of the excited energy levels; 2) when the π-levels are in the same order, inversion of the excited states occurs; 3) reversal of the occupied π-MO of the ground state causes the inversion of the excited states. For communication 7 see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1761–1766, October, 1993.     

脱羧氯雷他定的合成

脱羧氯雷他定 (ＤＣＬ)是一种有效的非镇定性抗组织胺 ,对过敏性鼻炎 ,糖尿病、咳嗽、普通感冒、流行性感冒、关节痛及其它不适症状都有很好的疗效[1～2 ] 。它克服了氯雷他定、酮康唑、红霉素、伊曲康唑等易引发黑色素瘤、纤维肉瘤、胃刺激、肥胖症、心律失调、传导紊乱等症状的缺点。且它的使用剂量只有氯雷他定的十分之一 ,有很好的市场前景和实际应用价值。ＭａｒｋＷ .Ｈｏｌｌａｄａｙｅｔａｌ[3] 在水溶液中由酸、碱催化得到了脱羧氯雷他定 ,但无具体操作和反应结果报道。Ａ .Ｋ .ＧｕｎｎａｒＡｂｅｒｇ[1] 直接用ＫＯＨ在绝对无水…     

Synthetic study of hepoxilins

Total synthesis of trioxilin (10S,11S,12S)-B₃ was performed starting from a hepoxilin synthon, (2S,3S)-2,3-epoxyundec-5-yn-1-ol, available from the corresponding allylic alcohol by Sharpless enantiodirected epoxidation. The synthesis features stereoselective (7 ∶ 1)syn-addition of the acetylenide anion to the intermediate (2S,3S)-2,3-(isopropylidenedioxy)undec-5-yn-1-al and regioselective partial hydrogenation of a triacetylene trioxilin precursor, which allowed the preparation of 14,15-dehydro-(10S,11S,12S)-TrXB₃. For part 8, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 545–551, March, 2000.     

Mechanistic study of the deamination reaction of guanine: a computational study

The mechanism for the deamination of guanine with H(2)O, OH(-), H(2)O/OH(-) and for GuaH(+) with H(2)O has been investigated using ab initio calculations. Optimized geometries of the reactants, transition states, intermediates, and products were determined at RHF/6-31G(d), MP2/6-31G(d), B3LYP/6-31G(d), and B3LYP/6-31+G(d) levels of theory. Energies were also determined at G3MP2, G3MP2B3, G4MP2, and CBS-QB3 levels of theory. Intrinsic reaction coordinate (IRC) calculations were performed to characterize the transition states on the potential energy surface. Thermodynamic properties (ΔE, ΔH, and ΔG), activation energies, enthalpies, and Gibbs free energies of activation were also calculated for each reaction investigated. All pathways yield an initial tetrahedral intermediate and an intermediate in the last step that dissociates to products via a 1,3-proton shift. At the G3MP2 level of theory, deamination with OH(-) was found to have an activation energy barrier of 155 kJ mol(-1) compared to 187 kJ mol(-1) for the reaction with H(2)O and 243 kJ mol(-1) for GuaH(+) with H(2)O. The lowest overall activation energy, 144 kJ mol(-1) at the G3MP2 level, was obtained for the deamination of guanine with H(2)O/OH(-). Due to a lack of experimental results for guanine deamination, a comparison is made with those of cytosine, whose deamination reaction parallels that of guanine.     

A study of naphthyridines

4,4-Diaryl-1,4-dihydro-2,3-benzo-1,8-naphthyridines have been synthesized by the cyclization of diaryl 2-arylaminopyridin-3-yl carbinols. The latter were obtained by the reaction of methyl 2-arylaminonicotinates with arylmagnesium halides. With acid chlorides, the 4,4-diaryl-1, 4-dihydro-2,3-benzo-1,8-naphthyridines form 1-acyl derivatives. The pK_a values of the 4,4-diaryl-1,4-dihydro-2,3-benzo-1,8-naphthyridines in nitrobenzene have been determined, and a correlation has been found of the pK _a values with the ^* constants of the substituents (r=0.955, ^*= –1.53, pK _a ^° calc=2.51, s=0.01).For Communication II, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 119–121, January, 1974.     

Mass-spectrometric study of benzopyridofulvenes

The dissociative ionization of benzopyridofulvenes that differ with respect to the position of the nitrogen atom in the azafluorene ring and the position and character of the substituents in the molecule was investigated. It is shown that the characteristic peculiarities of the fragmentation of these compounds can be explained by cyclization processes in the step involving the formation of [M-R]⁺ ions, where R=CH₃ and C₆H₅ and are the substituents attached to the exocyclic carbon atom. Calculations of the -bond energies of the molecular ion and the fragments by the Pariser-Parr-Pople method confirm the energie favorability of the formation of rings in the [M-R]⁺ions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 377–383, March, 1982.     

The study of Zr adsorption on nanodispersed hydroxyapatite: X-ray photoelectron study

Journal of Radioanalytical and Nuclear Chemistry - Elemental and phase composition of hydroxyapatite (HA) nanoparticle surface with absorbed zirconium were studied with X-ray photoelectron...     

A study of pyrazoles

The reactivity of pyrazolo[2, 3-a]pyridine in electrophilic substitution reactions has been studied. It has been shown that electrophilic attack is directed to position 3 (equivalent to position 4 of the pyrazole nucleus). The position of entry of the substituents was shown by chemical methods and was confirmed by a study of PMR spectra.     

A study of bromoporphins

The synthesis and characterizations of 2-bromoporphin, 5-bromoporphin, 5,15-dibromoporphin, and 5, 10, 15-tribromoporphin are described. Yields of the bromoporphins obtained with a variety of brominating agents are reported. Spectral properties were measured and, along with chemical properties, are presented as evidence for a preferred delocalization pathway in porphin.     

Thermogravimetric study of diatomites

The thermal curves of diatomites (kieselguhrs) in air display different profiles, depending on the type and quantity of impurities (carbonates, clays, etc.) present. TG and DTG runs can be used for a quick diagnosis of quality, but also give a nearly quantitative picture of the silica content of these minerals.

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Zusammenfassung In Abhängigkeit von Art und Menge der Verunreinigungen (Karbonate, Tonerde usw.) weisen die thermischen Kurven von Diatomiten (Kieselguhr) in Luft unterschiedlichen Verlauf auf. Einfache TG- und DTG-Untersuchungen können als Schnelldiagnose zur Bestimmung der Qualität benutzt werden und geben ausserdem noch ein nahezu quantitatives Bild über den Silikatgehalt dieser Mineralien.

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The authors acknowledge the financial support of this work by the Comisión Asesora de Investigatión Cientifica y Técnica, Spain, through Project No. PR84-0151.