Inexpensive, Operationally Simple Flow Reactor for Rapid, Chromatography Free Synthesis of Siloxane Based Liquid Crystals

We report on the hydrosilylation of terminal alkenes in flow using a “Karstedt-like” platinum-on-silica catalyst. A solution of alkene and siloxane in toluene was passed through the catalyst bed using a low pressure pump; the use of a high catalyst loading delivers quantitative β-addition of the siloxane to the alkene, hence the only purification required is removal of volatiles (toluene and siloxane). Following optimisation we synthesise a family of liquid crystalline siloxane terminated cyanobiphenyls, finding their properties to compare favourably to literature examples. The system and catalyst described is inexpensive, reusable, and chromatography free and thus prominently sustainable

Platinum Complexes with a Phosphino-Oxime/Oximate Ligand

The platinum(II) complex [PtCl2(COD)] (2; COD = 1,5- cyclooctadiene) reacted with 1 and 2 equiv. of 2-(diphenylphosphanyl) benzaldehyde oxime (1) to generate [PtCl2{¿2-(P,N)-2- Ph2PC6H4CH=NOH}] (3) and [Pt{¿2-(P,N)-2-Ph2PC6H4CH=NOH}2]- [Cl]2 (4), respectively. Deprotonation of the oxime hydroxyl group of 3 with Na2CO3 led to the selective formation of the dinuclear species (¿-O)-[PtCl{¿2-(P,N)-2-Ph2PC6H4CH=NO}]2 (5), while the related methylated derivative (¿-O)-[PtMe{¿2-(P,N)-2- Ph2PC6H4CH=NO}]2 (7) could be obtained from the direct reaction of [PtMe2(COD)] (6) with the phosphino-oxime ligand 1. In the case of 4, its treatment with Na2CO3 yielded complex [Pt({¿2-(P,N)-2-Ph2PC6H4CH=NO}2H)][Cl] (8), as a result of the deprotonation of only one of the OH groups of 4. On the other hand, contrary to what was observed with 6, no deprotonation of the oxime occurred in the reaction of [PtMe3I]4 (9) with 1, from which the mononuclear PtIV derivative fac-[PtIMe3{¿2-(P,N)- 2-Ph2PC6H4CH=NOH}] (10) was isolated. The solid-state structures of compounds 3, 4, 7 and 10 were determined by X-ray crystallography. In addition, the potential of all the synthesized complexes as catalysts for the dehydrogenative coupling of hydrosilanes with alcohols is also briefly discussed.Peer Reviewe

Konsumentenverhalten bei Nahrungsmitteln in Mecklenburg-Vorpommern

Available from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel Mb 722 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

From simple silanes to multifunctional systems: Synthesis and characterization of novel silicon-containing building blocks and silicon-organic chelate ligands

Die vorliegende Arbeit beschreibt die Synthese multifunktioneller siliciumhaltiger Synthesebausteine, die sich von (Chlormethyl)silanen ableiten und Verbindungen des allgemeinen Formeltyps R(4–n)Si(CH2X)n (n = 2–4; R = organischer Rest; X = funktionelle Gruppe) darstellen. Darüber hinaus wurden funktionalisierte siliciumhaltige Boronsäuren und Epoxide mit einem (2-Halogen-5-pyridyl)silan-Gerüst (Halogen = F, Cl) dargestellt. Die Charakterisierung der Zielverbindungen sowie aller auftretenden Zwischenstufen erfolgte durch NMR-Spektroskopie (1H, 13C, 11B, 15N, 19F, 29Si) und elementaranalytische Untersuchungen sowie in ausgewählten Fällen durch Einkristall-Röntgenstrukturanalyse. Die in dieser Arbeit beschriebenen multifunktionellen siliciumhaltigen Synthesebausteine sind zur Synthese neuartiger Silicium-Verbindungen, insbesondere Wirkstoffe, von Interesse und können in einigen Fällen auch als siliciumorganische Chelatliganden zur Komplexierung von Übergangsmetallen verwendet werden.This work describes the synthesis of multifunctional silicon-containing building blocks which derive from (chloromethyl)silanes and represent compounds of the general formula type R(4–n)Si(CH2X)n (n = 2–4; R = organyl group; X = functional group). Furthermore, functionalized silicon-containing boronic acids and epoxides with a (2-halogeno-5-pyridyl)silane skeleton (halogen = F, Cl) were prepared. All these compounds and the synthetic intermediates were characterized by NMR studies (1H, 13C, 11B, 15N, 19F, 29Si), elemental analyses, and in selected cases by single-crystal X-ray diffraction. The multifunctional silicon-containing building blocks described in this work are potential starting materials for the synthesis of novel silicon-containing compounds, especially drugs, and in some cases can be applied as silicon-based chelate ligands for the complexiation of transition metals