Carbon-13 spectra of some tetrahydropyridines. The structure of the tetrahydropyridines from 3,5-lutidine 1-oxide and mercaptans in acetic anhydride

The reaction of 3,5-lutidine 1-oxide ( 1 ) with t-butyl mereaptan in acetic anhydride, with or without triethylamine, was reinvestigated. There was obtained 2-t-butylthio-3,.5-lutidine as the major product, a small quantity of 3-(t-bulylthio)methyl-5-picoline, 1-acetyl-2,3-diacetoxy-3,5-dirnethyl-6-t-butylthio-1,2,3,6-tetrahydropyridine (which represents a structure revision) and l-acetyl-2,6-dihydroxy-3-t-butylthio-3,5-dimethyl-1,2,3,6-tetrahydropyridine. A similar reaction of 1 with 1-adamantyl mercaptan furnished 2-(l-adamantylthio)-3,5-lutidine and 1-acetyl-2,3-diacetoxy-3,5-dimethyl-6-(1-adamantylthio)-1,2,3,6-tetrahydropyridine. The structures of these new tetrahydropyridines were established primarily by carbon-13 nmr spectra.     

Thiazolo-N-hydroxyuracils

The partial Lossen degradation of the hydroxamic acid group at C-4 or C-5 of sodium 4,5-thiazoledicarbohydroxamate (IIIb) and its 2-methyl analog (IIIe) initiated a multicoursed reaction which furnished a mixture of thiazolo[4,5-d]- and thiazolo[5,4-d]-N-hydroxyuracils. The isomer distribution was sensitive to the solvent systems in which these reactions were carried out. The structure of the isomers so obtained was established by chemical and spectral methods.     

GLOBAL ANALYSIS OF FLUORESCENCE DECAY: APPLICATIONS TO SOME UNUSUAL EXPERIMENTAL AND THEORETICAL STUDIES

The methodology for the simultaneous analysis of fluorescence decay curves is shown to create the possibility for some new types of fluorescence decay experiments. These new experiments include the use of the T-format in anisotropy experiments without the need to match the timing characteristics of photomultiplier tubes. Decay surfaces obtained at multiple timing calibrations can be analyzed simultaneously to resolve widely differing decay rates. Methodologies are described for the discrimination of associative from nonassociative behavior for multiexponential anisotropy decay. A systems theory approach to the analysis of excited state reactions is described.     

Microchip electrophoresis for chiral separations

Microchip electrophoresis (MCE) is a promising new technique for the separation of enantiomers. This recently introduced technique enables chiral separations to be performed in seconds on tiny micromachined devices. This review is intended to give a brief introduction into the principles of chiral separations with MCE with regard to methodology and instrumentation. Different approaches to realize chiral separations in microfluidic devices are described and discussed. This review gives an overview of original work done in this field with emphasis on approaches to improve detection and resolution in chiral MCE.     

Accurate calibration of TXRF using microdroplet samples

TXRF has been applied in combination with VPD to the analysis of trace impurities in the native oxide layer of Si wafer surfaces down to the range of 10(8) atoms. cm(-2). Proper quantification of VPD/TXRF data requires calibration with microdroplet standard reference wafers. The precision of calibration function has been evaluated and found to allow quantification at a high level of 3 sigma confidence with microdroplet standard reference.     

Über Derivate des 5,5-Diphenyl-glykocyamidins

Zusammenfassung Es wird über die Kondensation von Benzil mit Guanidin, p-Toluolsulfonyl-guanidin und Dicyandiamid berichtet, die zu 5,5-Diphenylglykocyamidinen führt. Der Einfluß der Alkali-Menge und der Reaktionsdauer auf die Richtung der Kondensation werden untersucht. Weiters wird eine strukturbeweisende Zweitsynthese für 5,5-Diphenyl-N_exo-p-toluolsulfonyl-glykocyamidin angegeben.

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Derivatives of 5.5-diphenyl-glycocyamidine

Guanidine, p-toluenesulfonyl-guanidine or dicyandiamide react with benzil to give 5,5-diphenyl-glycocyamidines. The influence of the alkali concentration and the reaction time on the direction of the condensation is investigated. For 5,5-diphenyl-N_exo-p-toluenesulfonyl-glycocyamidine a structure proving synthesis is given.