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Diamine Incorporation in An Amorphous Nickel(II) Aluminosilicate
No full textTreatment of an amorphous nickel(II)-substituted aluminosilicate (NiAS) with 1,2-diaminoethane (en),
1,2-diaminopropane (pnd) and 1,3-diaminopropane (tmd) gives materials (NiAS-en, NiAS-pnd and NiAS-tmd) that are characterized by Ni/diamine ratio of 1:2, 1:1 and 1:1, respectively. The Ni2+ coordination environment is octahedral for NiAS-tmd (as it is for NiAS), tetragonally distored octahedral for NiAS-en, and probably trigonal bypiramidal for NiAS-pnd. The tmd ligand in NiAS-tmd is coordinated as a monodentate
Synthesis and Characterization of Some Nitro-Substituted Phthalocyanines of Nickel(II), Cobalt(II) and Copper(II)
No full textSynthesis of the peripherally substituted (phthalocyaninato)metal derivatives (NO2)4PcM (M α Ni, Co, Cu; NO2 groups are in 1,8,15,22- or 2,9,16,23-positions) is described, and their X-ray powder diffraction patterns, solubilities, electronic and infrared spectra, and thermal stability are reported. The complexes exhibit isomorphism and polymorphism, and they are more soluble than the corresponding MPcs. Their thermal stability increases in the series Co < Ni < Cu, being at the same time greater for the 2,9,16,23-tetranitro- than for the 1,8,15,22-tetranitro derivatives
Oxygen reduction on iron. Part III. An analysis of the rotating disk-ring electrode measurements in near neutral solutions
No full textThe kinetics of oxygen reduction were studied on iron in borate and bicarbonate buffered solutions, pH 9.8, using the rotating disk-ring method. Under these conditions O2 reduction occurs both on the oxidized surface and on the oxide-free one, depending on potential. On the oxidized surface the series mechanism was found to be operative. On the oxide-free surface the four-electron reduction was observed, but, due to the very small rate of H2O2 formation with respect to the total reduction current, a reliable distinction between the parallel and series mechanism could not be made. All the rate constants of the O2 and H2O2 reactions on the Fe surface were determined. No catalytic decomposition of H2O2 was found. The kinetics of the O2 reduction reaction is slower on more oxidized surfaces
Synthesis and Characterization of Some Nitro-Substituted Phthalocyanines of Nickel(II), Cobalt(II) and Copper(II)
No full textSynthesis of the peripherally substituted (phthalocyaninato)metal derivatives (NO2)4PcM (M α Ni, Co, Cu; NO2 groups are in 1,8,15,22- or 2,9,16,23-positions) is described, and their X-ray powder diffraction patterns, solubilities, electronic and infrared spectra, and thermal stability are reported. The complexes exhibit isomorphism and polymorphism, and they are more soluble than the corresponding MPcs. Their thermal stability increases in the series Co < Ni < Cu, being at the same time greater for the 2,9,16,23-tetranitro- than for the 1,8,15,22-tetranitro derivative
Preparation and properties of (2-nitrophtalocyanato)copper(II)
No full textThe synthesis of (2-nitrophthalocyanato)copper(II) is described, and its X-ray powder diffraction pattern, solubility, electronic and infrared spectra, and thermal stability are reported. The product contains as an impurity about a 5% mass of unsubstituted phthalocyaninatocopper(II)
Intramolekulska dehidratacija L-glutaminske kiseline
No full textA number of various thermal dehydrations of L-glutamic acid were performed in order to obtain crude L-pyroglutamic acid. Some old procedures and some new ones were investigated. Also, a great deal of work was done on the purification of crude L-pyroglutamic acid. We can say that among other very good procedures for synthesis and purification we can count our own, modified synthesis in aqueous solution of L-glutamic acid (acid: water = 1:3) and recrystallization from ethanol. The most efficient purification was carried out on ion-exchange resins (Dowex, Amberlite). Some new systems for TLC of L-glutamic acid and L-pyroglutamic acid were also examined .Pošto do sada još nije u potpunosti rešen postupak sinteze i ekonomičnog prečišćavanja L-piroglutaminske kiseline, izvršili smo ispitivanje različitih postupaka termičke intramolekulske dehidratacije L-glutaminske kiseline, kao i prečišćavanje dobijene sirove L-piroglutaminske kiseline u cilju dobijanja proizvoda većeg stepena čistoće. Uporedno si ispitivani i raniji poznati postupci i poređeni sa našim novim postupcima. Na osnovu naših rezultata može se zaključiti da je naročito pogodna sinteza iz vodenog rastvora L-glutaminske kiseline (1 deo kiseline i 3 dela vode) i prekristalisavanje sirovog produkta iz etanola. Najefikasnije prečišćavanje izvodi se pomoću jonoizmenjivačkih smola (Dowex, Amberlite)
The kinetic behavior of catalase immobilized on Amberlite IRA-410
Full text linkBeef liver catalase was immobilized on the strongly basic ion-exange resin
Amberlite IRA-410, and used to study the kinetics of the reaction of hydrogen
peroxide decomposition. The process of the immobilization was also followed.
Rate constants for the enzymatic reaction were determined for the initial period
and for the reaction as a whole. Reuse of the immobilized enzyme was also examined.
Rate constants at four temperatures in the range 20—40 °C were determined
and the energy and entropy of activation were calculated from rate data
A kinetic study of the thermal degradation of poly(dihexyl itaconate)
No full textThe kinetics of thermal degradation of poly(dihexyl itaconate) (PDHI), in the absence of oxygen, were determined on the basis of non-isothermal and isothermal TG data. Two PDHI samples of different weight average molar masses were used in the study. Two distinct DTG peaks were registered in the investigated range of 30°-600° C. Uniform values of the thermal degradation activation energy, Ea, (118 kJ mol) were obtained from non-isothermal data using the Flynn-Wall method for both samples up to mass losses of 60-70 %. The Ea's at higher mass losses averaged about 150 kJ mol. Corresponding Ea values were obtained from isothermal TG data analysed by classical kinetics. There seemed to be no influence of sample molar mass on the value of Ea
Synthesis and Characterization of Amorphous Nickel(II) Aluminosilicate
Full text linkAmorphous aluminosilicates containing about 12 wt.% nickel have been synthesized by cation exchange. Approximately 40 % of the nickel content is present in the form of octahedral [Ni(H20)6]2+ ions while the bulk of Ni2+ is coordinated both by H2O molecules and by oxygen atoms of the aluminosilicate framework. When the materials are heated in air at 350 oC, a change in the nickel coordination environment/geometry and possibly also a partial oxidation take place.Amorfni aluminosilikati sa oko 12 mas. % nikla dobijeni su jonskom izmenom. Oko 40% nikla nalazi se u obliku oktaedarski koordiniranih jona [Ni(H20)6]2+, a preostali nikal koordiniran je sa molekulima vode i kiseonikovim atomima iz aluminosilikatne rešetke. Zagrevanjem na vazduhu, na oko 350 0C dolazi do promena u koordinaciji, odnosno geometriji nikla, a moguće je da dolazi i do delimične oksidacije nikla