Traceless Solid Phase Synthesis with Polystyrene-Bound Tellurium and in Comparison with Polystyrene-Bound Selenium
作者:Thomas Ruhland、Jakob Torang、Henrik Pedersen、Jens Christian Madsen、Kia Svane Bang
DOI:10.1055/s-2004-831202
日期:——
A novel traceless linking strategy by use of polystyrene-bound tellurium is described. The application of the tellurium linker is demonstrated by the solid phase synthesis of a small library of single alkyl aryl ethers containing two points of diversity. Polystyrene-bound tellurium and polystyrene-bound selenium are compared by their cleavage performance under radical conditions (homolysis) at different
Green Traceless Cleavage from Resin-Bound Selenium and Tellurium and Analysis by 2D<sup>29</sup>Si/<sup>1</sup>H HR-MAS NMR Spectroscopy
作者:Thomas Ruhland、Jakob Torang、Henrik Pedersen、Jens Christian Madsen、Kia Svane Bang
DOI:10.1055/s-2005-865311
日期:——
A novel protocol for traceless cleavage from resin-bound selenium and tellurium is described. The toxic tributyltin hydride that has been used previously as reagent for cleavage from these resins by homolysis has been replaced by the less-toxic tris(trimethylsilyl)silane and tris(trimethylsilyl)germane. In addition, the remaining resin-bound chalcogenyl silane and germane residues were characterised by the use of high-resolution magic-angle spinning (HR-MAS) 2D 29Si/1H NMR spectroscopy.
Selective, Nickel-Catalyzed Hydrogenolysis of Aryl Ethers
作者:Alexey G. Sergeev、John F. Hartwig
DOI:10.1126/science.1200437
日期:2011.4.22
A catalyst that cleaves aryl-oxygen bonds but not carbon-carbon bonds may help improve lignin processing. Selectivehydrogenolysis of the aromatic carbon-oxygen (C-O) bonds in arylethers is an unsolved synthetic problem important for the generation of fuels and chemical feedstocks from biomass and for the liquefaction of coal. Currently, the hydrogenolysis of aromatic C-O bonds requires heterogeneous
裂解芳基-氧键但不裂解碳-碳键的催化剂可能有助于改善木质素加工。芳基醚中芳族碳-氧 (CO) 键的选择性氢解是一个未解决的合成问题,对于从生物质生产燃料和化学原料以及煤的液化很重要。目前,芳族 CO 键的氢解需要在高温和高压下运行的多相催化剂,并导致来自脂肪族 CO 键的竞争性氢解和芳烃加氢的产物混合物。在这里,我们报告了仅形成芳烃和醇的烷基芳基和二芳基醚中芳族 CO 键的氢解。该过程由可溶性镍卡宾配合物在 80 至 120°C 的温度下在 1 巴氢气下催化;醚底物的相对反应性比例为 Ar-OAr>>Ar-OMe>ArCH2-OMe(Ar,Aryl;Me,Methyl)。木质素模型化合物的氢解突出了这种方法将难熔芳醚生物聚合物转化为碳氢化合物的潜力。
Polymerizable liquid crystal composition and optically anisotropic medium
申请人:Kawamura Jyoji
公开号:US20070170394A1
公开(公告)日:2007-07-26
A polymerizable liquid crystal composition includes a liquid crystal compound having a polymerizable group, wherein the composition includes from 0.1 to 6.0% by weight of a (meth)acrylic copolymer (H), which
1) has a side chain containing a fluorine group, and a side chain containing a group represented by a general formula (h):
2) has a fluorine group content of 3 to 30% by weight, 3) has a ratio of side chains containing the group represented by the general formula (h) relative to the combined total of all side chains that falls within a range from 9 to 95 mol %, and 4) has a weight average molecular weight within a range from 10,000 to 300,000.
Alpha-hydroxyketone derivatives, liquid crystal compositions containing said derivatives, and liquid crystal devices using said compositions
申请人:Chisso Corporation
公开号:EP0409234A2
公开(公告)日:1991-01-23
α-hydroxyketone derivatives represented by the general formula (I) which are novel optically active compounds; liquid crystal compositions, such as chiral smectic or chiral nematic compositions, containing the derivatives; and liquid crystal devices using the compositions. General Formula (I)
wherein A and B are independently a radical represented by the general formula (II):
wherein R2 is an aliphatic hydrocarbon having 1 to 16 carbon atoms, which may contain -0- and may be substituted by a cyano group and/or a halogen atom,
are independently a single bond,
etc., X and Y are independently a single bond, or -CH2CH2-, etc., or an aliphatic hydrocarbon having 1 to 16 carbon atoms; R1 is an alkyl group, a phenyl group, or a cyclohexyl group; n is 0 or 1; and the asterisk (*) indicates an asymmetric carbon atom.
由通式(I)代表的α-羟基酮衍生物,是新型光学活性化合物;含有该衍生物的液晶组合物,如手性硅胶组合物或手性向列型组合物;以及使用该组合物的液晶器件。通式 (I)
其中 A 和 B 独立地为通式 (II) 所代表的基团:
其中 R2 是具有 1 至 16 个碳原子的脂肪族烃,可含有 -0- 并可被氰基和/或卤素原子取代、
独立地为单键、
等,X 和 Y 独立地为单键或-CH2CH2-等,或为具有 1 至 16 个碳原子的脂肪烃;R1 为烷基、苯基或环己基;n 为 0 或 1;星号(*)表示不对称碳原子。