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Conventional Catalyst (conventional + catalyst)
Selected AbstractsEvolution of iron catalysts for effective living radical polymerization: P,N chelate ligand for enhancement of catalytic performancesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2008Chihiro Uchiike Abstract Iron catalysts were evolved for more active transition metal-catalyzed living radical polymerization through design of the ligands. In situ introduction of P,N chelate-ligands, consisting of hetero-coordinating atoms [phosphine (P) and nitrogene (N)], onto FeBr2 effectively catalyzed living radical polymerization of methyl methacrylate (MMA) in conjunction with a bromide initiator, where the monomer-conversion reached over 90% without dropping the rates and the molecular weights of obtained PMMAs were well controlled. The benign effects of the "hetero-chelation" were demonstrated by comparative experiments with homo-chelate ligands (P,P, N,N), model compounds of the composed coordination site, and the combinations. We successfully achieved an isolation of iron complex with a P,N ligand [FeBr2(DMDPE); DMDPE: (R)- N,N -dimethyl-1-(2-(diphenylphosphino)phenyl)-ethanamine], which was superior to the conventional catalyst [FeBr2(Pn -Bu)2] with respect to controllability and activity, especially at the latter stage. The catalyst was almost quantitatively removed by water washing after polymerization. It was also effective for living polymerization of styrene. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6819,6827, 2008 [source] Fast living cationic polymerization accelerated by SnCl4.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2005A conventional catalyst, SnCl4, for cationic polymerization, combined with EtAlCl2 and an ester as an added base, has been used to realize the fast living cationic polymerization of not only alkyl vinyl ethers but also those containing hetero atoms in the pendant. Two important features of this system are the clearly defined roles of two Lewis acids: EtAlCl2 generates initiating species quantitatively from 1-(isobutoxy)ethyl acetate [CH3CH(OiBu)OCOCH3], and SnCl4 accelerates the polymerization, which proceeds with livingness (weight-average molecular weight/number-average molecular weight = 1.02,1.08) at a rate 103,105 greater than that with only EtAlCl2 (or Et1.5AlCl1.5). SnCl4 alone induces rapid and living-like polymerization but produces byproducts under similar reaction conditions. [source] Efficient Acylation of Anisole over Hierarchical Porous ZSM-5 StructureCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2010A. Padmanabhan Abstract Friedel-Crafts acylation is one of the most important methods to prepare aromatic ketones which are used in manufacturing fine and speciality chemicals, as well as pharmaceuticals. Herein, we report an efficient and convenient procedure for the acylation of anisole with acetic anhydride, using a hierarchical porous ZSM-5 catalyst. The hierarchical porous ZSM-5 catalyst was synthesized using styrene butadiene rubber (SBR) as macroporous template. The catalysts were characterized for their structural features by using XRD, SEM, and FT-IR analyses. The effect of temperature, molar ratio, and catalyst weight on the acylation of anisole was studied in detail. The reaction parameters such as anisole-to-acetic anhydride mole ratio, catalyst weight, and reaction temperature were optimized as 5:1, 0.2 g, and 70 °C, respectively. The method described here is environmentally benign and replaces the conventional catalyst by a highly active and reusable catalyst. [source] Formation of Cross-Linked Chloroperoxidase Aggregates in the Pores of Mesocellular Foams: Characterization by SANS and Catalytic PropertiesCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 2 2009Dirk Jung Abstract No escape: The formation of cross-linked chloroperoxidase aggregates (CPO-CLEAs) in the pores of mesocellular foam materials results in active biocatalysts that are more resistant to leaching than the conventional catalyst prepared by physisorption of chloroperoxidase. Small-angle neutron scattering (SANS) experiments clearly confirm that the CPO-CLEAs are located in the pores of the mesocellular foams. [source] | ||||||||||