Determination of cationic surfactants in soil samples by the disulphine blue active substance (DBAS) procedure

A method for the determination of cationic surfactants in soil samples was developed and applied to a biodegradation study. Five different cationic surfactants (benzalkonium chloride, 1-dodecyl-3-methylimidazolium bromide, didecyldimethylammonium bromide, trihexyl(tetradecyl)phosphonium bromide and trihexyl(tetradecyl)phosphonium chloride) were selected for the study with the developed method upon extraction from soil samples with methanol. The samples were subjected to analysis as disulphine blue active substances using a visible spectrophotometer. The limits of detection for the proposed method ranged from 2 to 27 μg/g, which enabled the determination of cationic surfactants in soil samples. The results obtained in the biodegradation study were confirmed using liquid chromatography coupled with tandem mass spectrometry.     

Highly enantioselective Henry reaction catalyzed by chiral tridentate heteroorganic ligands

New tridentate enantiomerically pure heteroatom catalysts, containing hydroxyl, sulfinyl and amino groups, proved to be highly efficient in the enantioselective nitroaldol (Henry) reaction to give the desired adducts in very high yields (up to 90%) and with ees up to 98%. The influence of the stereogenic centres located on the sulfinyl sulfur atom and in the amine moiety is also discussed.     

Eisen und Stahl

Ohne Zusammenfassung     

New highly efficient aziridine-functionalized tridentate sulfinyl catalysts for enantioselective diethylzinc addition to carbonyl compounds

New tridentate enantiomerically pure heteroorganic catalysts, containing hydroxyl, sulfinyl, and aziridine moieties, have proven to be highly efficient in the enantioselective diethylzinc addition to aryl and alkyl aldehydes to give the desired products in very high yields (up to 99%) and with ee’s up to 97%. The influence of the stereogenic centers located on the sulfinyl sulfur atom and in the aziridine moiety on the stereochemical course of the reaction are discussed.     

Cationic polymerization of styrene involving ionization of the C?Cl bond in ionic liquid/SO2 mixture

There has been a recent upsurge in interest in use of ionic liquids as reaction media for various chemical processes. Until recently, ionic liquids were considered as highly polar solvents. Our earlier investigation indicated that cationic polymerization of styrene initiated by aryl (alkyl) chlorides in ionic liquids may proceed even in the absence of coinitiator (Lewis acid). Polymerization, however, did not conform to controlled polymerization scheme. More recently, it has been claimed that ionic liquids are not as polar as it was previously assumed. Independently, high solubility of sulfur dioxide in ionic liquids was noticed. As sulfur dioxide displays a high ionizing power toward organic halides, we applied ionic liquid/sulfur dioxide mixture as a solvent in cationic polymerization of styrene initiated by aryl (alkyl) chlorides. Results show that in this reaction medium ionization of the C? Cl bond is facilitated, and the contribution of chain transfer reaction can be reduced as compared with polymerization in ionic liquid alone. Ionization of the C? Cl bond, however, is still not sufficiently fast to ensure conditions of controlled polymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5251–5257, 2009