共查询到20条相似文献,搜索用时 15 毫秒
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《Nachrichten aus der Chemie》2016,64(11):1127-1127
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Crystallographic report: 1,3,5,7‐Tetraisopropyl‐2,4,6,8,9,10‐hexathia‐1,3,5,7‐tetrastanna‐adamantane
The crystal structure of iPr4Sn4S6 consists of isolated molecules that contain an adamantane‐like Sn4S6 core. The tin atoms are coordinated nearly tetrahedrally, with Sn–S distances ranging from 2.397(1) to 2.411(1) Å. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Oliver Reiser 《Chemie in Unserer Zeit》2001,35(2):94-100
Palladium‐catalyzed coupling reactions belong to the most versatile processes for the construction of carbon‐carbon bonds. This article features the Heck, Stille, and Suzuki reaction, which are especially effective for the coupling of alkenes and arenes. 相似文献
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Graeme J. Gainsford Cornelis Lensink Andrew Falshaw 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):o650-o652
The novel title compound, C25H31O6P, contains rigid fused rings which are shown to be similar to the precursor structures. Weak C—H⋯O intermolecular interactions produce two‐dimensional sheets composed of R44(28) rings. 相似文献
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Annemarie A. M. L. Huijbrechts Junrong Huang Henk A. Schols Barend van Lagen Gerben M. Visser Carmen G. Boeriu Ernst J. R. Sudhölter 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2734-2744
New reactive unsaturated starch derivatives, 1‐allyloxy‐2‐hydroxy‐propyl‐starches (AHP‐starches), were synthesized by the reaction of waxy maize starch (WMS) and amylose‐enriched maize starch (AEMS) with allyl glycidyl ether in a heterogeneous alkaline suspension containing NaOH and Na2SO4. The degree of substitution (DS) was determined by 1H NMR spectroscopy, and a DS of 0.20 ± 0.01 was found for both AHP‐WMS and AHP‐AEMS, respectively. The AHP derivatives of WMS and AEMS were further characterized with 1H and 13C NMR. It was shown that the AHP substitution was located on the C‐6 hydroxyl group of the glucose residues in the starch. The substitution pattern of the AHP groups along the polymer chain was randomly clustered, as determined by enzymatic digestion using pullulanase, α‐amylase, and amyloglucosidase, followed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis of the digestion products. With X‐ray diffraction and scanning electron microscopy, no changes in the granular morphology and crystallinity between the unmodified starches and AHP‐starches were detected. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2734–2744, 2007 相似文献
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Franois Brisse Mohamed Atfani Jean‐Yves Bergeron Francine Blanger‐Garipy Michel Armand 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):190-192
The title compounds of sulfur, C10H6N2O4S2, (I), and selenium, C10H6N2O4Se2, (II), are isomorphous. The crystallographically centrosymmetric molecules are planar. The bond distances and angles, except for those involving the S and Se atoms, are comparable. The molecules are disposed in layers parallel to the bc plane. The molecular axes differ by 75° for (I) and by 80° for (II) from one layer to the next. 相似文献
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Toshifumi Satoh Tomoko Imai Norihiko Sugie Ryuji Nonokawa Kazuaki Yokota Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2002,40(8):965-970
The bulk cyclopolymerization of diepisulfide, 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐1,2:5,6‐tetradeoxy‐D ‐mannitol ( 1 ), was studied using R4N+Br? (R = ? CH3, C2H5, C3H7, C4H9, and C7H15) and (C4H9)4N+X? (X = Cl, I, NO3, and ClO4) as the initiators. All the bulk polymerizations of 1 using quaternary tetraalkylammonium salts at 90 °C proceeded without gelation even at high conversion to produce gel‐free polymers consisting of 2,5‐anhydro‐1,5‐dithio‐D ‐glucitol (I) as the major cyclic repeating unit along with 1,5‐anhydro‐2,5‐dithio‐D ‐mannitol (II) and the desulfurized acyclic unit (III) as the minor units. The polymerization rate and molar fraction of the I unit increased with the increasing alkyl chain length of the tetraalkylammonium cation and the increasing nucleophilicity of the counteranion. Tetrabutylammonium chloride exhibited the highest catalytic activity and the highest stereoselectivity, that is, the thiosugar polymer with I:II:III = 81:15:4 and a number‐average molecular weight of 31.9 × 103 was obtained in 85% yield for a polymerization time of 0.5 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 965–970, 2002 相似文献
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Tuncer Hkelek Elif Ece Kaya Zeynel Kl 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(4):o278-o280
The title compound, C22H30N2O2·H2O, is an 18‐membered diaza‐crown ether ligand containing two ether O and two aza N atoms. In the macrocyclic ring, the mean N⋯O distance is 4.526 (4) Å. The macrocyclic inner‐hole size, estimated as twice the mean distance of the donor atoms from their centroid, is ∼2.29 Å. 相似文献