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Various Reaction Conditions (various + reaction_condition)

Distribution by Scientific Domains
Polymers and Materials Science40%
Chemistry40%

Selected Abstracts

Rapid and Easy Access to (E)-1,3-Enynes, 1,3-Diynes and Allenes Starting from Propargylic Acetals, Exploiting the Different Reactivity of Lithium and Mixed Lithium,Potassium Organometallic Reagents

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 35 2007
Marco Blangetti
Abstract The treatment of propargylic acetals with various lithium and mixed lithium,potassium Schlosser reagents, has allowed a one-pot synthesis of (E)-1,3-enynes, 1,3-diynes and allenes, depending on the reaction conditions and the selected base. Various reaction conditions were investigated in order to control the selectivity of the reactions and to obtain pure products. The metallation,elimination sequence in the presence of a suitable electrophile has provided a linear route to functionalized (E)-conjugated enynes, diynes and allenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Synthesis of N -Acetyl-,-aminobutyric Acid via Amidocarbonylation: A Case Study

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2003
Dirk Gördes
Abstract The synthesis of N -acetyl-,-aminobutyric acid by amidocarbonylation of propionaldehyde with acetamide in the presence of palladium catalysts is studied in detail. The influence of various reaction conditions and compositions (e.g., the co-catalysts acid and bromide) on the yield of N -acetyl-,-aminobutyric acid is shown. For the first time it is demonstrated that the palladium-catalyzed amidocarbonylations of aldehydes can be run with significantly lower halide concentrations (<30 mol,%) without a major yield decrease. While phosphine-free catalyst systems give best yields at low CO pressure, phosphine-ligated palladium catalysts lead to better yields at higher CO pressure. At low palladium loadings (<0.1 mol,%), unwanted condensation reactions of propionaldehyde become increasingly competitive. [source]

Unusual cationic copolymerization behavior of a six-membered ring spiro-orthocarbonate bearing adamantane backbones with a monofunctional epoxide

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2005
Tetsuo Hino
Abstract Copolymerizations of a six-membered ring spiro-orthocarbonate bearing adamantane backbones (AD - SOC, 1) and a monofunctional epoxide, PGE, in the presence of cationic initiators such as Sc(OTf)3 were carried out under various reaction conditions. As a result, instead of the anticipated poly(ether-ether-carbonate) 11, two types of copolyethers (12 and 18) consisting of two or three types of ether components having different substituent groups were unusually formed along with the evolution of carbon dioxide gas, in which AD - SOC efficiently acted as the corresponding oxetane equivalent monomers 3 and 4. Furthermore, the copolymerization behavior, including the formation of copolyethers 12 and 18, unexpectedly and significantly depended on the reaction conditions, such as the concentration of the initiator. For example, the copolymerizations with 5 mol % of Sc(OTf)3 mainly afforded copolyether 18, while those with 1 mol % mainly gave copolyether 12. In addition, treatments with 5 mol % of Sc(OTf)3 also yielded CH2Cl2, THF, and DMF-insoluble networked products, indicating relatively higher thermal stability compared with a common polyether. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1729,1740, 2005 [source]

Ammonium oxotrifluorotitanate: morphology control and conversion to anatase TiO2

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008
Lei Zhou
Abstract Uniform ammonium oxotrifluorotitanate (NH4TiOF3) mesocrystals were synthesized from an aqueous solution containing (NH4)2TiF6 and H3BO3 in presence of nonionic surfactant. Effects of various reaction conditions on the morphology of the NH4TiOF3 mesocrystals were examined by electron microscopy techniques. Results indicate that static solution, high surfactant concentration and low reaction temperature enhance the formation of uniform NH4TiOF3 mesocrystals with regular shapes. By sintering in atmosphere, the NH4TiOF3 mesocrystals were converted to anatase TiO2, which retain the original shapes of the NH4TiOF3 precursor due to similarities on their atom structures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Factorial design of nanosized polyisoprene synthesis via differential microemulsion polymerization

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2010
Bunthita Suppaibulsuk
Abstract The synthesis of nanosized polyisoprene latex was carried out by differential microemulsion polymerization using 2, 2,-Azoisobutyronitrile (AIBN) initiator system under various reaction conditions. A fractional factorial experimental design was applied to study the effects of reaction variables: amount of initiator and surfactant, monomer-to-water ratio, reaction temperature, and stirring speed on rubber particle size and monomer conversion. The analysis of the results from the design showed the main effects on the observed response and the amount of initiator, reaction temperature and stirring speed in the range of the test had significant effects on polyisoprene particle size. The significant effects on monomer conversion were reaction temperature, stirring speed, and interaction between reaction temperature and stirring speed in the range of the test. The optimum conditions gave highest monomer conversion of 90% and average particle size of polyisoprene of 27,nm. The nanosized polyisoprene was also characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Copyright © 2009 John Wiley & Sons, Ltd. [source]