Separation of C27, C28 and C29 sterols by reversed-phase high-performance liquid chromatography on small particles.

The application of reversed-phase high-performance liquid chromatography to the analytical- and preparative-scale separation of sterols has been evaluated. The capacity factors, k', for a number of compounds chromatographed on a muBondapak C18 (LESS THAN 10 MUM) COLUMN ARE PRESENTED. C27, C28 and C29 sterols and also sterols differing in degree of unsaturation could be readily separated as their acetates in this system. The present reversed-phase chromatographic method is apparently not as selective as silver nitrate-silica gel thin-layer chromatography for the position of unsaturation in the sterol molecule.     

The addition of diazomethane to β-ethynylpyridines

The action of diazomethane on -ethynylpyridines substituted in the pyridine ring or analogous compounds with an alkyl group in place of the acetylenic hydrogen atom has given 3-(pyridin-3-yl)pyrazoles. When the acetylenic hydrogen atom is replaced by an electron-accepting carboxyl group, the polarization of the triple bond interferes with the reaction, which then leads to a mixture of 3- and 4-(pyridin-3-yl)pyrazoles with the simultaneous methylation of the nitrogen of the pyrazole ring.     

Coordination compounds of Co(II), Ni(II), and Cu(II) valerates and benzoates with semicarbazide

Complexes of Co(II), Ni(II), and Cu(II) valerates and benzoates with semicarbazide were prepared. The compounds were characterized by chemical analysis, X-ray phase analysis, IR spectroscopy, diffuse reflection spectroscopy, and thermal gravimetric analysis.     

Structural transformations of silicates upon prolonged grinding

Structural changes in diopside, CaMgSi₂O₆, and wollastonite, CaSiO₃, upon prolonged (up to 84 h) grinding in a mechanic agate mortar under environmental conditions were studied. X-ray phase analysis and specific surface measurements were used to show that the stage of amorphization of the starting substances under mechanical treatment is followed by the formation of a partially ordered phase whose reflexes correspond to reflexes of α-quartz. Possible mechanisms of the structural transformations were discussed.     

Microdétermination quantitative sur papier

Résumé On propose une méthode de dosage de Cu²⁺ en quantités comprises entre 0,3 et 20g sur papier FN-1 imprégné de Zn(C₂H₅OCS₂)₂. Les pH des solutions sont compris entre 2 et 5. Le dosage est effectué à±6,4% près. Sa durée est d'environ 30 minutes.

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Quantitative microdetermination on paper. Microdetermination of copper in the vorm of xanthogenate

Summary A method of assaying copper II in amounts between 0.3 and 20g on FN-1 paper impregnated with Zn(C₂H₅OCS₂)₂ is proposed. The pH of the solutions are between 2 and 5. The assay is ±6.4% accurate and lasts about 30 minutes.

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Zusammenfassung Ein Verfahren zur Bestimmung von Cu²⁺ in Mengen zwischen 0,3 und 20g wurde vorgeschlagen. Chromatographie-Papier FN-1 wird dazu mit einer Lösung von Zinkxanthogenat imprägniert. Das pH der Lösungen wird zwischen 2 und 5 gehalten. Die Ergebnisse sind auf ±6,4% genau. Die Dauer der Bestimmung beträgt etwa 30 min.

     

Photochemical chlorination of 2-trichloromethyl-1,3-dioxolane

The photochemical chlorination of 2-trichloromethyl-1,3-dioxolane proceeds only at the carbon atoms in the 4 and 5 positions. The structures of the resulting 2-trichloromethyl-4-chloro-and 2-trichloromethyl-4,5-dichloro-1,3-dioxolanes were proved by means of the IR spectra and chemical transformations.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1611–1613, December, 1973.     

Determination of the distribution of cannabinoids in cannabis resin from the Lebanon using HPLC. Part III

Samples taken from 61 slabs of cannabis resin originating in The Lebanon were examined by high performance liquid chromatography. The slabs were derived from seizures of cannabis resin made over a three-year period. From a study of 14 of these samples, taken from bags which bore a number of identical stamp marks, it was shown that there was a correlation between the cannabinoid distribution and the marks. The remaining 47 samples of cannabis resin, all of which were from bags with different marks, were each found to have a unique cannabinoid distribution. Such an examination can therefore be used to aid investigations where evidence of a common origin is sought.     

The effect of bubbles on the measured electrochemical parameters during hydrogen evolution on nickel

The hydrogen evoluton reaction has been investigated at nickel rotating and vertical stationary electrodes in 1 M HC1. Steady state current—potential, impedance—potential and potential step—current—time transients results are reported. The impedance is analysed by equivalent circuit to produce double layr capacity—potential, ohrnic resistance—potential (and charge transfer resistance—potential) curves. Some deductions are made about the bubble layer and its effect on the electron transfer mechanism for the reaction.     

Liquid chromatographic and mass spectral analysis of 1-(3,4-methylenedioxyphenyl)-3-butanamines, homologues of 3,4-methylenedioxyamphetamines

The 1-(3,4-methylenedioxyphenyl)-3-butanamines (HMDAs) are prepared via reductive amination of the corresponding ketone with a series of low molecular weight alkylamines. These amines are homologues of the N-substituted 3,4-methylenedioxyamphetamines (MDAs). Compounds of the HMDA series have UV absorption properties similar to the MDAs because both series contain the same 3,4-methylenedioxyphenyl chromophore. The HMDAs are separated via reversed-phase liquid chromatographic methods using a C18 stationary phase and an acidic aqueous acetonitrile mobile phase. The mass spectra of these potential designer drugs are very similar to the spectra of the MDA homologues having the same N-substituent.