- Two novel organic-inorganic hybrid compounds with straight and zigzag chain alignments of Cu(II) centers: Synthesis, crystal structure, spectroscopy, thermal analysis and magnetism
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Abstract Two hybrid salts, viz. bis(guanidinium) bis(oxalato)cuprate(II) (1) and bis(2-aminopyridinium) bis(oxalato)cuprate(II) trihydrate (2) have been synthesized and characterized by elemental and thermal analyses, IR spectroscopy, single-crystal X-ray diffraction and SQUID magnetometry. Compounds 1 and 2 crystallize in the monoclinic P21/c and triclinic P1ˉ space groups, respectively. In both structures, the four-coordinated Cu(II) ion in [Cu(C2O4)2]2- unit weakly interacts with two axial O-atoms of neighboring units to build a prolate CuO6 octahedron, with regular axial Cu-O bonds of 2.825 ? in 1, whereas in 2 two different Cu-O bonds (2.814 ? and 2.701 ?) are found. In 1, stacking of [Cu(C2O4)2]2- units across internal symmetry-related O-atoms results in equidistantly spaced monomers, thus forming straight Cu(II) chains with regular spacing of Cu?Cu = 3.582 ?. By contrast, in 2, stacking of the [Cu(C2O4)2]2- entities occurs via external symmetry-related O-atoms, yielding zigzag Cu(II) chains with shorter intra-dimer spacing of [Cu?Cu]intra = 3.430 ? and longer inter-dimer spacing of [Cu?Cu]inter = 4.961 ?. The anhydrated compound 1 is stable up to 250 °C, whereas the hydrated compound 2 shows a significant weight loss of solvent water molecules at about 70°C, followed by the decomposition of the network. The magnetic measurements in the 2-300 K temperature range revealed weak antiferromagnetic coupling in the two hybrid salts.
- Nenwa, Justin,Djomo, Edith D.,Nfor, Emmanuel N.,Djonwouo, Patrick L.,Mbarki, Mohammed,Fokwa, Boniface P.T.
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- Analysis of the CO2 and NH3 reaction in an aqueous solution by 2D IR COS: Formation of bicarbonate and carbamate
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The two-dimensional (2D) infrared correlation spectra obtained from the reaction time- and concentrationdependent IR spectra elucidates the reaction of CO2 and NH3 in an aqueous solution for CO2 absorption. In the synchron
- Park, HoSeok,Jung, Young Mee,You, Jong Kyun,Hong, Won Hi,Kim, Jong-Nam
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p. 6558 - 6562
(2009/04/13)
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- PROCESS FOR PRODUCING METHIONINE
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A process for producing methionine by hydrolysis of 5-(β-methylmercaptoethyl)hydantoin in the presence of an alkali, in which the concentration of hydrogen sulfide is 5 ppm or less in a solution used for hydrolysis comprising 5-(β-methylmercaptoethyl)hydantoin and the alkali, whereby methionine can be stably produced for a long period of time.
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Page/Page column 2
(2008/12/07)
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- NH4CaCl3, the Reactive Intermediate Phase in a Synthesis of CaCl2
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The reaction of CaCO3 with NH4Cl leads to formation of CaCl2. In this reaction an intermediate phase is formed, that is be characterized as NH4CaCl3. This intermediate phase crystallizes in the GdFeO3 type and decomposes at elevated temperatures to yield CaCl2 and NH4Cl. The fomation andthe decomposition of this intermediate phase as well as the formation o f CaCl2 were studied with X-ray and thermoanalyical methods.
- Naegele, Andreas,Gibson, Katharina,Glaser, Jochen,Meyer, H.-Juergen
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- Oxidation of Thiourea by Iodate: a New Type of Oligo-oscillatory Reaction
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In the oxidation of thiourea by iodate in weakly acidic solution the concentration of iodide may exhibit several extrema.The number of extrema mainly depends on the initial ratio of the concentrations of thiourea and iodate, and is at most four. the first step of the reaction results in the formation of iodide which then reacts with iodate to give iodine.The latter oxidizes thiourea in several steps, the end products being sulphate ions, ammonium ions, and carbon dioxide.Taking into account the independently determined rate constants for the sub-systems, the change in the concentrations of iodide and iodine with time can be calculated.There is good agreement between the experimental and theoretical curves.
- Rabai, Gyula,Beck, Mihaly T.
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p. 1669 - 1672
(2007/10/02)
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- Process for preparing thiourea dioxide
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According to this invention there is provided a process for preparing thiourea dioxide characterized in that in the production of thiourea dioxide by the reaction of thiourea and hydrogen peroxide in an aqueous solvent, ammonium bicarbonate is added to the reaction solution at a proper time.
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- Imidazoles and 2-alkyl imidazoles and method for their manufacture
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The method is for manufacturing imidazoles corresponding to the general formula: STR1 in which R represents hydrogen or an alkyl radical of 1 to 17 carbon atoms. Glyoxal is condensed with an aliphatic aldehyde and ammonia, in a hydroalcoholic medium at a pH comprised between 6 and 8. The glyoxal is in the form of its bisulfite combination and the ammonia being supplied by an ammonium salt of a weak acid.
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- PROLINE DERIVATIVES AND RELATED COMPOUNDS
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New proline derivatives and related compounds which have the general formula STR1 are useful as angiotensin converting enzyme inhibitors.
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- KINETICS OF UREA DECOMPOSITION IN PRESENCE OF MONOAMMONIUM PHOSPHATE AT ELEVATED TEMPERATURS
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Manufacture of mixed nitrogen-phosphorus or nitrogen- phosphorus- potassium fertilizers, with the use of urea, its aqueous solutions or melts, or the urea-containing melt formed as an intermediate product in the synthesis of urea, is of great industrial interest. The authors investigated decomposition of urea in presence of monoammonium phosphate, in relation to manufacture of a nitrogen- phosphorus fertilizer by treatment of urea-containing melts with orthophosphoric acid at 100 to 150 C. Decomposition ofrea in this system is described by a kinetic equation of the second order. Equations are given for calculating the degree of decomposition of urea as a function of the time after mixing of the urea solution with monoammonium phosphate and for finding the time required for complete conversion of monoammonium phosphate into diammonium phosphate at different temperatures. It is suggested that the decomposition of urea in the system studied may proceed by direct formation of ammonium carbonates, without the intermediate stage of isomerization to ammonium cyanate.
- SARBAEV AN,TIMOSHENKO LS
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