Hydroxyphenyl-1-methylpyridinium-jodide als potentielle Reaktivatoren von mit Organophosphor-Verbindungen vergifteten Acetylcholinesterasen

Hydroxyphenyl-1-methylpyridinium-iodide as Potential Reactivators of Acetylcholinesterase Poisoned with Organophosphorus Compounds . It was our aim to reactivate acetylcholinesterase poisoned with sarin. We synthesized 2-(o-hydroxyphenyl)-1-methylpyridinium-iodide ( 9 ), 2-(p-hydroxyphenyl)-1-methylpyridinium-iodide ( 19 ) and 4-(o-hydroxyphenyl)-1-methylpyridinium-iodide ( 14 ) as potential reactivators. All substances showed moderate toxicity against mice; their reactivity potency in vitro and in vivo was negligible.     

Reactions of hexamethylditin with alkylmercury salts I. Stoichiometry and rate step

Hexamethylditin in methanol solution reacts rapidly with mercuric chloride to yield mercury and trimethyltin chloride. With alkylmercuric salts the reaction is complex, yielding tetraalkyltin and/or dialkylmercury, depending upon the reactivity of the alkylmercuric salt. An electrophilic substitution mechanism involving trimethylstannyl mercurials as transient intermediates is suggested. The reaction of hexaalkylditin with diarylmercury is suggested to follow a homolyric pathway.     

Direct versus resonances mediated F+OH collisions on a new 3A" potential energy surface

A theoretical study of the F(2P) + OH(2Pi) --> HF(1Sigma+) + O(3P) reactive collisions is carried out on a new global potential energy surface (PES) of the ground 3A" adiabatic electronic state. The ab initio calculations are based on multireference configuration interaction calculations, using the aug-cc-pVTZ extended basis sets of Dunning et al. A functional representation of the PES shows no nominal barrier to reaction, contrary to previous results by others. Wave packet and quasiclassical trajectory calculations have been performed for this PES to study the F + OH(v = 0,j) reactive collision. The comparison was performed at fixed and constant values of the total angular momentum from 0 to 110 and relative translational energy up to 0.8 eV. The reaction presents a dynamical barrier, essentially due to the zero-point energy for the bending vibration near the saddle point. This determines two different reaction mechanisms. At energies higher than approximately 0.125 eV the reaction is direct, while below that value it is indirect and mediated by heavy-light-heavy resonances. Such resonances, also found in the simulations of the photodetachment spectrum of the triatomic anion, manifest themselves in the quasiclassical simulations, too, where they are associated to periodic orbits.     

Einige analytische Eigenschaften von 1,3-Dimethyl-4,5-diaminouracil

Zusammenfassung 1,3-Dimethyl-4,5-diaminouracil (DAL) hat sich als sehr empfindliches Reagens zum selektiven Nachweis von Co²⁺-Ionen im stark alkalischen Medium einer Phosphatpufferlösung (p_H=11,20) erwiesen. Es wurden vier Additionsverbindungen von DAL mit den Zentralatomen Cd(II), Pd(II), Ni(II) und Co(II) im Verhältnis Me DAL=1 2 hergestellt. Spektrophotometrische Untersuchungen weisen darauf hin, daß bei p_H 6 bis 7 eine Komplexverbindung im Verhältnis CoDAL=12 gebildet wird.

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Summary 1,3-dimethyl-4,5-diaminouracil (DAL) has been found to be a very sensitive reagent for the selective detection of Co²⁺ ions in strong alkaline medium of a phosphate buffer solution (p_H=11.20). Four addition compounds of DAL with the central atoms Cd(II), Pd(II), Ni(II) and Co(II) with the ratio MeDal=12 have been prepared. Spectrophotometric studies indicate that at p_H=6–7, complex compound is produced with the ratio CoDAL=12.

     

Derivatization of tertiary amphetamines with 9-fluorenylmethyl chloroformate for liquid chromatography: determination of N-methylephedrine

The fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC) was evaluated for the derivatization of tertiary amphetamines prior to liquid chromatographic analysis. Conditions for the derivatization were investigated, including the reaction time, the derivatization reagent concentration and the pH, using N-methylephedrine as a model compound. On the basis of these studies, a method for the quantification of N-methylephedrine is presented. The method involves derivatization with FMOC at ambient temperature and separation of the derivatives formed on a LiChrospher C18, 5 microns, 125 x 4 mm id column using acetonitrile-water gradient elution. The proposed procedure shows good linearity, accuracy and reproducibility in the 1.0-25.0 micrograms mL-1 concentration range. The limit of detection was 0.1 microgram mL-1 and the limit of quantification was 0.5 microgram mL-1. The utility of the assay was demonstrated by determining N-methylephedrine in water and urine samples.     

Mikrobestimmung einiger Elemente in organischen Verbindungen nach Aufschluß mit Kalium

Zusammenfassung Der Aufschlnß halogenhaltiger organischer Substanzen mit metallischem Kalium kann auch in einem offenen Gefäß durchgeführt werden, wenn zwischen die Substanz und das Kalium eine Schicht aus Glaskügelchen gesetzt wird. Nach Desaktivierung der störenden Kohleteilchen titriert man die Halogenide argentometrisch gegen Variaminblauacetat als Redoxindikator mit 0,01-n oder im Fall von Jod mit 0,002-n Silbernitratlösung. Zur Analyse flüchtiger Verbindungen ist das Verfahren nicht geeignet.

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Summary The decomposition of organic compounds containing halogen by metallic potassium can be conducted also in an open vessel if a layer of small glass balls is placed between the sample and the potassium. After the interfering carbon particles have been deactivated, the halides are titrated argentometrically with Variamine blue as redox indicator; 0.01N silver nitrate is used, or 0.002N in the case of iodide. The method is not suitable for the analysis of volatile compounds.

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Résumé L'attaque de substances organiques halogénées par le potassium peut être effectuée en récipient ouvert lorsque l'on intercale entre la substance et le potassium une couche de petites billes de verre. Après désactivation des particules gênantes de charbon les halogénures sont titrés argentométriquement, en utilisant l'acétate de bleu de variamine comme indicateur d'oxydoréduction, avec une solution 0,01N de nitrate d'argent ou 0,002N dans le cas de l'iode. La technique ne se prête pas à l'analyse de combinaisons volatiles.

     

Characterization of plant oils on a monolithic silica column by high-performance liquid chromatography-atmospheric pressure chemical lonization-mass spectrometry

Summary Five plant oils (peanut, pumpkin seed, sesame seed, soybean, and wheat germ) have been analyzed by high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (HPLC-APCI-MS). Gradient elution was performed with acetone-acetonitrile mobile phases on a short monolithic silica column (SilicaROD, RP-18e, 50 mm×4.6 mm). Identification of plant oil triacylglycerols (TAG) was based on the pseudomolecular ion [M+H]⁺ and the diacylglycerol [M−RCO₂]⁺ fragments. Positional isomers of triacylglycerols were identified from the relative intensities of the [M-RCO₂]⁺ fragments. Principal-component analysis, used to find similarities and differences between the different oils, indicated that the different plant oils could be clearly differentiated according to their triacylglycerol composition. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Extraction of cesium into nitrobenzene using hydrogen dicarbollylcobaitate in the presence of dibenzo-24-crown-8

Extraction of microamounts of cesium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻) in the presence of dibenzo-24-crown-8 (DB24C8,L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺ and CsL⁺ are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

A practical synthesis of (+/-)-alpha-isosparteine from a tetraoxobispidine core

[reaction: see text] The title alkaloid was synthesized in racemic form from 3,7-diallyl-2,4,6,8-tetraoxo-3,7-diazabicyclo[3.3.1]nonane (7) by a regioselective diallylation reaction followed by double ring-closing olefin metathesis and exhaustive reduction. Tetraoxobispidine 7 was itself prepared in three simple operations from dimethyl malonate. The entire sequence to alpha-isosparteine was conducted on a multigram scale and proceeded without recourse to chromatography.