Showing papers by "Tyge Greibrokk published in 1984"

New system for delivery of the mobile phase in supercritical fluid chromatography

Abstract: Des modifications simples sur les pompes a piston permettent un debit stable et reproductible de CO 2 ; il s'agit de systemes de refroidissement sur la tete de pompe et les vannes

Chemistry of gem-dihalocyclopropanes. XX: The effect of methyl and phenyl substituents on the vinylcyclopropylidene−cyclopentenylidene rearrangement

Abstract: On etudie la reaction d'une serie de dibromo-1,1 alcenyl-2 cyclopropanes avec le methyllithium. Dans la plupart des cas on obtient des cyclopentadienes et/ou des vinylallenes. On observe un effet de substituant important sur le rearrangement carbene-carbene conduisant au cyclopentadiene, d'origine essentiellement sterique

Preparation and characterization of dinitroperylenes.

Abstract: Dinitroperylenes have been synthesized and purified by HPLC. Based on NMR, MS and UV data, the main isomers were identified as 3,6-,3,7-,3,9- and 3,10-dinitroperylene.

Separation of isomers of nitro‐polycyclic aromatic hydrocarbons

Abstract: Since positional isomers of several nitro-polycyclic aromatic hydrocarbons (nitro-PAH) contain widely different mutagenic properties, methods for separating the isomers were investigated. High performance liquid chromatography with dichloromethane in hexane on silica gave the best resolution for the majority of the compounds. A few groups of isomers were better resolved with other modifiers or with reversed phases. Of the reversed phase systems, methanol-water gave better resolution than acetonitrile-water. With dichloromethane/hexane on silica, the retention was found to depend on the presence of a bay nitro group (first), the number of H atoms peri to the nitro group (second), and the length/breadth ratio of the molecule (third). Front electron density calculations were combined with the structure-retention relations in making tentative structure assignments of minor isomers of nitro-PAH.