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Diethyl Zinc (diethyl + zinc)
Selected AbstractsFacile and Efficient Reduction of Ketones in the Presence of Zinc Catalysts Modified by Phenol LigandsCHEMISTRY - AN ASIAN JOURNAL, Issue 9 2010Stephan Enthaler Dr. Abstract In the present study, the zinc-catalyzed hydrosilylation of various ketones to give their corresponding alcohols has been examined in detail. Diethyl zinc that can be modified by easily accessible phenol ligands allows the efficient reduction of various aryl and alkyl ketones. By using a practical in situ catalyst, excellent turnover frequencies up to 1000,h,1 and a broad functional group tolerance were achieved. Im Rahmen dieser Arbeit wird die Zink-katalysierte Hydrosilylierung von Ketonen zu den entsprechenden Silylethern mit anschließender Hydrolyse zu deren Alkoholen vorgestellt. Wobei exzellente Ausbeuten und Umsätze durch die Modifikation des katalytisch eingesetzten Diethylzink mit Phenolen erreicht werden konnten. Nach genauer Untersuchung verschiedenster Reaktionsparameter konnten turnover frequencies (TOF) von ca. 1000,h,1 erzielt werden. Die hervorragenden Eigenschaften des Katalysatorsystems konnte weiterhin in der Hydrosilylierung verschiedenster Ketone erfolgreich gezeigt werden. Zum besseren Verständnis der Reaktion wurden verschiedene mechanistische Experimente durchgeführt. [source] Atomic Layer Deposition of ZnO in Quantum Dot Thin Films,ADVANCED MATERIALS, Issue 2 2009Alexandre Pourret CdSeS/CdS/ZnS quantum dot thin films subjected to ZnO atomic layer deposition at 100°C shows photoluminescence (PL) modulation. The PL is quenched during each exposure to diethyl zinc. However, the PL is restored upon subsequent exposure to water. [source] Synthesis and enantioselectivities of soluble polymers incorporating optically active binaphthyl and binaphtholJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Xiaowei Zou Abstract A polymer (P-1) was synthesized through the polymerization of (S)-6,6,-dibromo-3,3,-dibutyl-1,1,-binaphthol with (S)-2,2,-dioctoxy-1,1,-binaphthyl-6,6,-boronic acid in a Pd-catalyzed Suzuki reaction, and another polymer (P-2) was synthesized through the polymerization of (S)-6,6,-dibromo-3,3,-dibutyl-1,1,-binaphthol with (S)-6,6,-diethynyl-2,2,-dioctoxy-1,1,-binaphthyl in a Pd-catalyzed Sonogashira reaction. The two polymers showed good solubility in some common solvents and were characterized with NMR, Fourier transform infrared, gel permeation chromatography, and circular dichroism spectroscopy. The application of the chiral monomers and polymers in the asymmetric addition of diethyl zinc to benzaldehyde was studied. The results indicated that P-1, P-2, and the monomer (S)-3,3,-dibutyl-1,1,-binaphthol were efficient ligands in the asymmetric addition of diethyl zinc to benzaldehyde. The chiral polymer ligands P-1 and P-2 were more efficient than their monomeric version, (S)-3,3,-dibutyl-1,1,-binaphthol, and could be easily recovered and reused without a loss of catalytic activity or enantioselectivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Synthesis and characterization of amphiphilic block copolymers with allyl side-groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2007Xiuli Hu Abstract The synthesis of a new cyclic carbonate monomer containing an allyl group was reported and its biodegradable amphiphilic block copolymer, poly(ethylene glycol)- block -poly(L -lactide- co -5-methyl-5-allyloxycarbonyl-propylene carbonate) [PEG- b -P(LA- co -MAC)] was synthesized by ring-opening polymerization (ROP) of L -lactide (LA) and 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) in the presence of poly (ethylene glycol) as a macroinitiator, with diethyl zinc as a catalyst. 13C NMR and 1H NMR were used for microstructure identification of the copolymers. The copolymer could form micelles in aqueous solution. The core of the micelles is built of the hydrophobic P(LA- co -MAC) chains, whereas the shell is set up by the hydrophilic PEG blocks. The micelles exhibited a homogeneous spherical morphology and unimodal size distribution. By using the cyclic carbonate monomer containing allyl side-groups, crosslinking of the PEG- b -P(LA- co -MAC) inner core was possible. The adhesion and spreading of ECV-304 cells on the copolymer were better than that on PLA films. Therefore, this biodegradable amphiphilic block copolymer is expected to be used as a biomaterial for drug delivery and tissue engineering. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5518,5528, 2007 [source] Synthesis and reactivity of allyl nickel(II) N -heterocyclic carbene enolate complexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2007Stefan Benson Abstract Two new N -heterocyclic carbene enolate nickel(II) allyl complexes have been prepared and their activity towards ethylene polymerization was investigated. It was found that in the presence of diethyl zinc, the carbene enolate complex bearing a nitro substituent produces highly linear polyethylene of modest molecular weight and high polydispersity. The influence of the reaction parameters on catalytic activity and the characteristics of the resulting polymer were investigated through systematic variation of the time, temperature, and diethyl zinc concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45:3637,3647, 2007 [source] Atomic layer deposition of Zn1,xMgxO buffer layers for Cu(In,Ga)Se2 solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 3 2007T. Törndahl Abstract Fabrication of Zn1,xMgxO films by atomic layer deposition (ALD) has been studied for use as buffer layers in Cu(In,Ga)Se2 (CIGS)-based solar cell devices. The Zn1,xMgxO films were grown using diethyl zinc, bis-cyclopentadienyl magnesium and water as precursors in the temperature range from 105 to 180°C. Single-phase ZnO-like films were obtained for x,<,0·2, followed by a two phase region of ZnO- and MgO-like structures for higher Mg concentrations. Increasing optical band gaps of up to above 3·8,eV were obtained for Zn1,xMgxO with increasing x. It was found that the composition of the Zn1,xMgxO films varied as an effect of deposition temperature as well as by increasing the relative amount of magnesium precursor pulses during film growth. Completely Cd-free CIGS-based solar cells devices with ALD-Zn1,xMgxO buffer layers were fabricated and showed efficiencies of up to 14·1%, which was higher than that of the CdS references. Copyright © 2006 John Wiley & Sons, Ltd. [source] Asymmetric 1,4-conjugation addition of diethylzinc to cyclic enones catalyzed by a self-assembled copper complexAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2009Shaohua Gou Abstract A new self-assembled catalyst system based on copper complex was developed for the 1,4-conjugation addition of diethyl zinc to cyclic enones. The self-assembled catalyst was readily prepared from (R)-[1,1,]binaphthalenyl-2,2,-diamine (1a), (L)-tryptophan (3f) and copper(I) chloride (CuCl). Several enones were found to be suitable substrates in the presence of the self-assembled copper catalyst [10 mol% (R)-1a, 10 mol% (L)-3f and 10 mol% CuCl] under optimized conditions. The desired products were afforded with high isolated yields (up to 98%) and moderate to good enantioselectivities (up to 80% ee) in mild conditions (at 0 °C). Copyright © 2009 John Wiley & Sons, Ltd. [source] Copper-Catalyzed Asymmetric Conjugate Addition with Chiral SimplePhos Ligands,CHEMISTRY - A EUROPEAN JOURNAL, Issue 40 2009Laëtitia Palais Abstract SimplePhos ligands represent a novel class of monodentate chiral ligands based on a chiral amine moiety and flexible diaryl groups on the phosphorous atom. They can be easily prepared by two different pathways and they can be highly functionalised. Herein we report the copper-catalysed asymmetric conjugate addition of diethyl zinc and trialkylaluminium reagents with SimplePhos ligands, which gives high enantioselectivity with cyclic enones, acyclic enones and nitro-olefins, with up to 98.6,%,ee. Of particular interest is the reaction of trialkylaluminium reagents with a wide range of 3-substituted enones, thus allowing the formation of stereogenic quaternary carbon centres. [source] | |||||||||||||