03201nas a2200289   4500008004100000022001400041245009400055210006900149260006700218300001400285490000700299520215700306653000602463653001602469653005502485653002202540653002702562653004802589653001802637653003602655653002402691653003102715653001202746100001502758700001602773856012202789       2005                        eng d  a0887-624X00aNovel tridentate nitrogen donor as ligand in copper catalyzed ATRP of methyl methacrylate0 aNovel tridentate nitrogen donor as ligand in copper catalyzed AT  a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcNOV  a4996-50080 v433 a<p>A tridentate ligand, BPIEP: 2,6-bis[1-(2,6-diisopropyl phenylimino) ethyl] pyridine, having central pyridine unit and two peripheral imine coordination sites was effectively employed in controlled/''living'' radical polymerization of MXU at 90 degrees C in toluene as solvent, (CuBr)-Br-I as catalyst, and ethyl-2-bromoisobutyrate (EBiB) as initiator resulting in well-defined polymers with polydispersities M-W/M-n &lt;= 1.23. The rate of polymerization follows first-order kinetics, k(app) = 3.4 x 10(-5) s(-1), indicating the presence of low radical concentration ([P*] &lt;= 10(-8)) throughout the reaction. The polymerization rate attains a maximum at a ligand-to-metal ratio of 2:1 in toluene at 90 degrees C. The solvent concentration (v/v, with respect to monomer) has a significant effect on the polymerization kinetics. The polymerization is faster in polar solvents like, diphenylether, and anisole, as compared to toluene. Increasing the monomer concentration in toluene resulted in a better control of polymerization. The molecular weights (M-n,M-SEC) increased linearly with conversion and were found to be higher than predicted molecular (M-n,M-Cal). However, the polydispersity remained narrow, i.e., &lt;= 1.23. The initiator efficiency at lower monomer concentration approaches a value of 0.7 in 110 min as compared to 0.5 in 330 min at higher monomer concentration. The aging of the copper salt complexed. with BPIEP had a beneficial effect and resulted in polymers with narrow polydispersitities and higher conversion. PMMA obtained at room temperature in toluene (33%, v/v) gave PDI of 1.22 (Mn = 8500) in 48 h whereas, at 50 degrees C the PDI is 1.18 (Ma = 10,300), which is achieved in 23 h. The plot of In kapp versus 1/T gave an apparent activation energy of polymerization as (Delta E-app(not equal)) 58.29 KJ/mol and enthalpy of equilibrium (Delta H-eq(0)) to 28.8 KJ/mol. Reverse ATRP of MMA was successfully performed using AIBN in bulk as well as solution. The controlled nature of the polymerization reaction was established through kinetic studies and chain extension experiments. (c) 2005 Wiley Periodicals, Inc.</p>10a210a6-bis [1-(210a6-diisopropyl phenylimino) ethyl] pyridine (BPIEP)10aActivation energy10aapparent rate constant10aAtom transfer radical polymerization (ATRP)10adiphenylether10aethyl-2-bromoisobutyrate (EBiB)10amethyl methacrylate10apolydispersity index (PDI)10aToluene1 aMittal, A.1 aSivaram, S.  uhttps://library.ncl.res.in/content/novel-tridentate-nitrogen-donor-ligand-copper-catalyzed-atrp-methyl-methacrylate-102440nas a2200253   4500008004100000022001400041245010300055210006900158260007300227300000900300490000800309520155700317653001401874653001501888653001201903653001801915653002501933653002401958653001401982653001301996100002202009700002802031856012702059       2006                        eng d  a1381-116900aEffect of calcination temperature on the catalytic activity of zirconia-supported heteropoly acids0 aEffect of calcination temperature on the catalytic activity of z  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL  a8-150 v2533 a<p>Zirconia-supported silicotungstic acid (15% STA) catalyst with different calcination temperatures (600-850 degrees C) was prepared by suspending zirconium oxyhydroxide in methanol solution of STA followed by drying and calcination. These catalysts were characterized by XRD, FTIR pyridine adsorption and DRUV-vis spectroscopy. The catalysts showed both Bronsted as well as Lewis acidity and 15% STA on zirconia calcined at 750 degrees C (15 SZ-750) had the highest Bronsted acidity. Characterization of 15 SZ-750 catalyst by Raman spectroscopy showed the presence of zirconia-anchored mono-oxotungstate as the major tungsten species present in this catalyst. These catalysts were used in benzoylation of veratrole with benzoic anhydride and 15 SZ-750 catalyst showed the highest activity. For catalyst with support calcined at different temperatures before HPA impregnation, catalytic activity decreases as the support calcination temperature increases due to the decrease in Bronsted acidity. Comparison of the catalytic activity of 15 SZ-750 with that of zirconia-supported phosphotungstic acid (15%, calcined at 750 degrees C, 15 PZ-750) in benzoylation of veratrole with benzoic anhydride, acylation of anisole with acetic anhydride and in alkylation of diphenylether with 1-dodecene showed that 15 SZ-750 catalyst has higher activity and deactivation resistance due to its higher Bronsted acidity. The deactivated catalyst could be regenerated by calcination without appreciable loss in activity. (c) 2006 Elsevier B.V. All rights reserved.</p>10aAcylation10aAlkylation10aAnisole10adiphenylether10aPhosphotungstic acid10aSilicotungstic acid10averatrole10aZirconia1 aDevassy, Biju, M.1 aHalligudi, Shivaraj, B.  uhttps://library.ncl.res.in/content/effect-calcination-temperature-catalytic-activity-zirconia-supported-heteropoly-acids-0