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901.
Alberto Hernn‐Gmez Emma Herd Eva Hevia Alan R. Kennedy Paul Knochel Konrad Koszinowski Sophia M. Manolikakes Robert E. Mulvey Christoph Schnegelsberg 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(10):2744-2748
The pivalates RZnOPiv⋅Mg(OPiv)X⋅n LiCl (OPiv=pivalate; R=aryl; X=Cl, Br, I) stand out amongst salt‐supported organometallic reagents, because apart from their effectiveness in Negishi cross‐coupling reactions, they show more resistance to attack by moist air than conventional organometallic compounds. Herein a combination of synthesis, coupling applications, X‐ray crystallographic studies, NMR (including DOSY) studies, and ESI mass spectrometric studies provide details of these pivalate reagents in their own right. A p‐tolyl case system shows that in [D8]THF solution these reagents exist as separated Me(p‐C6H4)ZnCl and Mg(OPiv)2 species. Air exposure tests and X‐ray crystallographic studies indicate that Mg(OPiv)2 enhances the air stability of aryl zinc species by sequestering H2O contaminants. Coupling reactions of Me(p‐C6H4)ZnX (where X=different salts) with 4‐bromoanisole highlight the importance of the presence of Mg(OPiv)2. Insight into the role of LiCl in these multicomponent mixtures is provided by the molecular structure of [(THF)2Li2(Cl)2(OPiv)2Zn]. 相似文献
902.
A three step synthesis of novel ‘multi-site’ water soluble phase transfer catalyst viz., α,α′-bis(triethyl ammonium methylene chloride) β-phenyl ethene and its utility in various organic biphase reactions are described. 相似文献
903.
We consider various quotients of the C*-algebra of bounded operators on a nonseparable Hilbert space, and prove in some cases that, assuming some restriction of the Generalized Continuum Hypothesis, there are many outer automorphisms. 相似文献
904.
Kenneth J. Olejar Sudip Ray Arianna Ricci Paul A. Kilmartin 《Cellulose (London, England)》2014,21(6):4545-4556
Agro-wastes represent an abundant and economical source of antioxidant compounds. Extraction and incorporation of antioxidants from these compounds into ethyl cellulose films provides the basis for an active packaging material. Grape tannin extract (GT) incorporation into ethyl cellulose results in hydrogen bonding between polyphenols and ethyl cellulose strands, which allows for the polyphenols to remain active and to be securely incorporated. Incorporation of 0.5 % GT in ethyl cellulose produced a significant increase (p < 0.01) in antioxidant activity while not altering physical or mechanical properties. A higher loading of GT at 3.0 % into ethyl cellulose resulted in further improvement in antioxidant activity (12-fold), while a slight decrease in the tensile properties was noted due to the plasticizing effect of GT as a consequence of disruption of the intermolecular hydrogen bonding. 相似文献
905.
Satyasankar Jana Vivek Arjunan Vasantha Ludger Paul Stubbs Anbanandam Parthiban Julius G. Vancso 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3260-3273
Vinylimidazole‐based asymmetric ion pair comonomers ( IPC s) which are free from nonpolymerizable counter ions have been synthesized, characterized and polymerized by free radical polymerization (FRP), atom transfer radical polymerization (ATRP), and reversible addition‐fragmentation chain transfer (RAFT) mediated polymerizations in solution and by dispersion polymerization in water. The asymmetric nature of IPC s is due to the fact that cationic component of these IPCs is derived from vinylimidazole (VIm) and anionic component is derived from either styrenesulfonate (SS) or 2‐acrylamido‐2‐methyl‐1‐propanesulfonate. Although under ATRP, conversions are either very low or negligible, FRP and RAFT produces polymers with high to moderate monomer conversions but with different solubility characteristics. This investigation provides insight to the polymerization behavior of each component of the asymmetric IPCs and also its effects on composition and solubility characteristics of the resulting polymers. The IPCs studied here are high temperature ionic liquid and thus the polymers synthesized from these IPCs are highly ionic in nature and possess very strong intermolecular interactions which makes some of these IPC based polymers completely insoluble in organic and aqueous solvents. This highly ionic interaction is exploited to synthesize ionically crosslinked PMMA. MMA on copolymerization with 5–6 mol % of IPC yielded copolymer which is insoluble in common organic solvents like THF, DMF, etc., unlike homo PMMA. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3260–3273 相似文献
906.
907.
908.
Paul Lescot 《Journal of Pure and Applied Algebra》2012,216(5):1004-1015
We investigate the algebraic and topological preliminaries to a geometry in characteristic one. 相似文献
909.
Dennis Courtney Paul S. Muhly Samuel W. Schmidt 《Complex Analysis and Operator Theory》2012,6(1):163-188
If b is an inner function, then composition with b induces an endomorphism, β, of
L¥(\mathbbT){L^\infty({\mathbb{T}})} that leaves
H¥(\mathbbT){H^\infty({\mathbb{T}})} invariant. We investigate the structure of the endomorphisms of
B(L2(\mathbbT)){B(L^2({\mathbb{T}}))} and
B(H2(\mathbbT)){B(H^2({\mathbb{T}}))} that implement β through the representations of
L¥(\mathbbT){L^\infty({\mathbb{T}})} and
H¥(\mathbbT){H^\infty({\mathbb{T}})} in terms of multiplication operators on
L2(\mathbbT){L^2({\mathbb{T}})} and
H2(\mathbbT){H^2({\mathbb{T}})} . Our analysis, which is based on work of Rochberg and McDonald, will wind its way through the theory of composition operators
on spaces of analytic functions to recent work on Cuntz families of isometries and Hilbert C*-modules. 相似文献
910.
Subhasis Paul Dr. Joyram Guin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4412-4419
Herein, an operationally simple, environmentally benign and effective method for intermolecular radical hydroacylation of unactivated substrates by employing photo-induced hydrogen atom transfer (HAT) initiation is described. The use of commercially available and inexpensive photoinitiators (Ph2CO and NHPI) makes the process attractive. The olefin hydroacylation protocol applies to a wide array of substrates bearing numerous functional groups and many complex structural units. The reaction proves to be scalable (up to 5 g). Different functionalized fatty acids, petrochemicals and naturally occurring alkanes can be synthesized with this protocol. A radical chain mechanism is implicated in the process. 相似文献