Platinum-Catalyzed Reduction of DMF by 1,1,3,3-Tetramethyldisiloxane, HMeSi2OSiMe2H: New Intermediates HSiMe2OSiMe2OCH2NMe2 and HSiMe2(OSiMe2)3OCH2NMe2 and Their Further Chemical Reactivity
摘要:
The use of Karstedt's catalyst to study the reduction of Me2NCHO (DMF) by the popular "dual SiH"-containing tetramethyldisiloxane, HMe2SiOSiMe2H (1), has revealed that the first step in the process involves an initial single hydrosilylation to form HSiMe2OSiMe2OCH2NMe2 (3). This intermediate is readily isolated and purified via distillation. In the continued presence of the catalyst, 3 transforms to the transient tetrasiloxane HMe2SiOSiMe2OSiMe2OSiMe2OCH2NMe2 (4), along with the formation of Me3N. The tetrasiloxane 4 itself transforms to Me3N and (Me2SiO) (n = 4-6). Despite the demonstrated reactivity of 3, it can also be used to perform the expected metal-catalyzed hydrosilylation chemistry of the SiH group as well as reactions of the SiOCH2NMe2 functionality involving siloxane chain extension and is thus an important new reagent for siloxane chemistry.
A series of siloxane-based monomeric and dimeric liquid crystals (LCs) bearing cholesteryl mesogenic groups were newly synthesized and their phase transition behavior was investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). All the siloxane-based LCs obtained in this study showed a smectic A phase in a wide temperature range. Among
Carbonyl and olefin hydrosilylation mediated by an air-stable phosphorus(<scp>iii</scp>) dication under mild conditions
作者:Ryan J. Andrews、Saurabh S. Chitnis、Douglas W. Stephan
DOI:10.1039/c9cc02460c
日期:——
The readily-accessible, air-stable Lewis acid [(terpy)PPh][B(C6F5)4]21 is shown to mediate the hydrosilylation of aldehydes, ketones, and olefins. The utility and mechanism of these hydrosilylations are considered.
已显示出易于获得的,空气稳定的路易斯酸[(terpy)PPh] [B(C 6 F 5)4 ] 2 1可介导醛,酮和烯烃的氢化硅烷化。考虑了这些氢甲硅烷基化的效用和机理。
Sugar complexation to silicone boronic acids
作者:Michael A. Brook、Laura Dodge、Yang Chen、Ferdinand Gonzaga、Hazem Amarne
DOI:10.1039/c2cc37438b
日期:——
A new class of surface-active compounds based on the combination of silicones and boronic acids is described. The properties of the compounds can be tuned by manipulation of both the hydrophobic (silicone size and 3D structure) and hydrophilic components (by binding different saccharides to the boronic acid). Stabilization of the four-coordinate boron structure is provided by Tris buffer that also maintains neutral pH to suppress silicone hydrolysis.
A liquid-crystalline perylene tetracarboxylic bisimide derivative bearing trisiloxan-2-yl moieties: influence on mesomorphic properties and electron transport
Mesomorphic and electron transport properties are compared for liquid-crystalline perylene tetracarboxylic bisimide derivatives bearing linear disiloxane and trisiloxane chains, as well as trisiloxan-2-yl groups.
novel class of bent-core molecules with oligo(siloxane) or carbosilane units at both ends was synthesized and the self-organization of these molecules was investigated by polarizing microscopy, DSC, X-ray scattering, dielectric and electrooptical methods. Depending on the size of the silicon-containing segments, smectic and columnar liquidcrystallinephases are formed. Most smectic phases are low birefringent