7738-94-5Relevant articles and documents
UV-vis spectroscopic determination of the dissociation constant of bichromate from 160 to 400°C
Chlistunoff, Jerzy B.,Johnston, Keith P.
, p. 3993 - 4003 (1998)
On the basis of direct measurements by UV-vis spectroscopy, the dissociation constant of bichromate was found to decrease with temperature from 160 to 400°C. For fixed Cr(VI) and KOH concentrations, the molal concentration of HCrO4- initially increases with temperature but decreases again in the vicinity of water's critical point, where the density decreases substantially. The decrease in HCrO4- at high temperature and low density may be attributed to (K+)(CrO42-) ion pairs, to a high degree of electrostriction about CrO42-, which facilitates the reaction HCrO4- + OH- = CrO42- + H2O, and to ion activity coefficients.
Oxidative Dissolution of Chromium(III) Oxides by Metaperiodate Ions in Perchloric Acid
Mills, Andrew,Sawunyama, Phillip
, p. 3389 - 3394 (1993)
The kinetics of oxidative dissolution of a number of different samples of chromium(III) oxide by periodate ions in 1 mol dcm-3 HClO4 solution have been studied and the results interpreted using the inverse-cubic rate law.The metaperiodate acts as a two-electron oxidant and the overall reaction stoichiometry involves the reaction of 3 mol of periodate with 1 mol of Cr(III) oxide.From a detailed study of the kinetics of dissolution the rate-determining step appears to be the reaction between an adsorbed periodate ion and its associated Cr(III) oxide surface site, withinhibition by one of the reaction products, iodate, through competitive adsorption.Analysis of the kinetic data generates values for the Langmuir adsorption coefficients for periodate and iodate ions on highly hydrated Cr(III) oxide of 84 +/- 8 and 2600 +/- 370 dm3 mol-1, respectively.The Cr(III) oxide-periodate reaction has a high overall activation energy, 82 +/- 6 kJ mol-1.The kinetics of dissolution of highly hydrated Cr(III) oxide under conditions in which the simple inverse-cubic rate law function does not apply can be successfully predicted using a simple kinetic model.
Theoretical and experimental investigation of the thermochemistry of CrO2(OH)2(g)
Opila, Elizabeth J.,Myers, Dwight L.,Jacobson, Nathan S.,Nielsen, Ida M. B.,Johnson, Dereck F.,Olminsky, Jami K.,Allendor, Mark D.
, p. 1971 - 1980 (2007)
In this paper, we report the results of equilibrium pressure measurements designed to identify the volatile species in the Cr-O-H system and to resolve some of the discrepancies in existing experimental data. In addition, ab initio calculations were performed to lend confidence to a theoretical approach for predicting the thermochemistry of chromium-containing compounds. Equilibrium pressure data for CrO2(OH)2 were measured by the transpiration technique for the reaction 0.5Cr2O3(s) + 0.75O2(g) + H2O(g) = CrO2(OH)2(g) over a temperature range of 573 to 1173 K at 1 bar total pressure. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to analyze the condensate in order to quantify the concentration of Cr-containing volatile species. The resulting experimentally measured thermodynamic functions are compared to those computed using B3LYP density functional theory and the coupled-cluster singles and doubles method with a perturbative correction for connected triple substitutions [CCSD(T)].
Vaporisation of chromia in humid air
Gindorf,Singheiser,Hilpert
, p. 384 - 387 (2005)
Thermodynamic data for the computation of the vaporisation of Cr 2O3(s) in humid air show significant deviations between each other which lead to large differences in the computed partial pressures. The vaporisation of Cr2O3(s) in air with different humidities, p(H2O)=0.0007 bar to p(H2O)=0.3 bar, was, therefore, investigated at constant temperature of 1223 K by the vapour transpiration method. The results obtained were explained by the formation of CrO3(g) as major vapour species at low p(H2O) and the formation of CrO2(OH)2(g) as major vapour species at high p(H2O). The pressures evaluated are compared with those obtained by thermodynamic computations using different data bases.
Gemcitabine derivatives nanoparticles
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Page/Page column 4, (2009/05/28)
The invention concerns a 2′,2′-difluoro-2′-deoxycytidine derivative of general formula (I), wherein: R1, R2 and R3, identical or different, represent independently of one another, a hydrogen atom or an at least C18 hydrocarbon acyl radical and of such conformation that it is capable of providing the compound of general formula (I), a compacted form in a polar solvent medium, at least one of groups R1, R2 and R3 being other than a hydrogen atom.
PROCESS FOR PREPARING (S)-PRAMIPEXOLE AND ITS INTERMEDIATES
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Page/Page column 16, (2008/06/13)
The present invention relates to an improved process for the preparation of (S)- 2,6-diamino-4,5,6,7-tetrahydrobenzothiazole of formula (II) useful in the preparation of pramipexole or (S)-2,6-amino-6-(n-propylamino)-4,5,6,7-tetrahydrobenzothiazole of formula (I) and its pharmaceutically acceptable salts or solvates thereof. The present invention further provides a process for the preparation of Pramipexole and its pharmaceutically acceptable salts, hydrates, solvates thereof.
PYRROLIDINE DERIVATIVES AS OXYTOCIN ANTAGONISTS
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Page 30-31, (2008/06/13)
The present invention relates to novel pyrrolidine derivative of formula (I), its geometrical isomers, its optically active forms as enantiomers, diastereomers, mixtures of these and its racemate forms, as well as salts thereof, wherein R1 is selected from the group comprising or consisting of H and C1-C6-alkyl, for the prevention and/or treatment of preterm labor, premature birth or dysmenorrhea.
PROCESS FOR THE PREPARATION OF METAL ACETYLACETONATES
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Page 13, (2008/06/13)
The present invention provides an improved, economical and environmmentally benign process for metal complexes of acetylacetone having the general formula, M(acac)n wherein M is a metal cation selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Ca, Mg, Mo, Ru, Re, U, Th, Ce, Na, K, Rb, Cs, V, Cr, and Mn etc., n is an integer which corresponds to the electrovalence of M, are obtained by reacting the corresponding metal hydroxide, metal hydrated oxide or metal oxide with a stoichiometric amount of acetylacetone and separating the product.
Intermediate for the production of 1-[2-dimethylamino-1-(4-methoxyphenyl)-ethyl]-cyclohexanol
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Page 9, (2008/06/13)
Processes for the preparation of Venlafaxine (IX) via the novel epoxy-nitrile intermediate (I), which when subjected to hydrogenation forms compound (X), and may subsequently be reduced to yield the desired product (IX). The epoxy-nitrile intermediate (I) itself may be synthesised via various alternative reaction strategies, from a range of starting materials. E.g. 4-methoxy-benzaldehyde (VI), upon treatment with cyclohexyl magnesium bromide yields compound (V). This in turn may be oxidised to yield compound (III), which forms compound (II) on treatment with an α-keto-halogenation agent. Cyanation of compound (II), then yields the desired epoxy nitrile intermediate (I), from which Venlafaxine (IX) may be synthesised.
Oxidative displacement and addition reactions of F-tert -butyl hypochlorite with metal chlorides and oxidative additions to several elements
Canich, Joann M.,Gard, Gary L.,Shreeve, JeaN'Ne M.
, p. 441 - 444 (2008/10/08)
Transition-metal and post-transition-metal chlorides underwent oxidative displacement and oxidative addition reactions with F-tert-butyl hypochlorite to form new F-tert-butoxides. Thus, when (CF3)3COCl was reacted with VOCl3, TiCl4, and CrO2Cl2, the stable compounds VO[(CF3)3CO]3, Ti[(CF3)3CO]4, and CrO2[(CF3)3CO]2 were formed. With Vaska's compound, oxidative addition occurred at iridium but the phenyl groups of P(C6H5)3 were also involved. UCl4, Cu2Cl2, SnCl4, and SiCl4 did not react under the experimental conditions used. F-tert-Butyl hypochlorite has also been shown to add oxidatively to such elements as sulfur, lead, tellurium, bismuth, and iodine to form S[(CF3)3CO]4, Pb[(CF3)3CO]2, Te[(CF3)3CO]4, Bi[(CF3)3CO]3, and I[(CF3)3CO]3, respectively. With (C2H5)2NH, (CF3)3COH formed a 1:1 adduct.
