共查询到20条相似文献,搜索用时 26 毫秒
1.
F. Bousmina L. Zayani D. Ben Hassen-Chehimi N. Kbir-Ariguib M. Trabelsi-Ayedi 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):763-768
Summary. The diagram of the ternary system Mg2+/Cl−, SO4
2−–H2O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram,
which are MgSO4·6H2O, MgSO4·7H2O, and MgCl2·6H2O. The solubility field of MgSO4·7H2O is important whereas those of MgSO4·6H2O and MgCl2·6H2O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO4:MgCl2=2.73:33.80 and MgSO4: MgCl2=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg2+/Cl−, SO4
2−–H2O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.
Corresponding author. E-mail: ariguib@planet.tn
Received October 16, 2002; accepted (revised) December 3, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70th birthday 相似文献
2.
Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates.
These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC2O4 as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite
Na2Cu2+(C2O4)2·2H2O.
High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two
higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and
857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison
the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost
at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II)
oxalate as compared to the synthetic compound which is the dihydrate. 相似文献
3.
A. S. Kubasov E. Yu. Matveev E. S. Turyshev I. N. Polyakova K. Yu. Zhizhin N. T. Kuznetsov 《Doklady Chemistry》2017,477(1):257-260
The interaction of the [B10H10]2– and [B12H12]2– anions with aliphatic and aromatic nitro compounds (RNO2, where R = Et, n-Pr, i-Pr, tert-Bu, Ph) has been studied under irradiation with visible and UV light. It has been shown that, depending on the reaction conditions, both mono- and disubstituted nitro-closo-decaborates can be selectively obtained in yields up to 50%. 相似文献
4.
V. V. Sharutin V. S. Senchurin O. K. Sharutina 《Russian Journal of Inorganic Chemistry》2012,57(3):398-401
The complex [(HOCH2)3CNH3] 2 + [HgI4]2? (I) was synthesized by reacting (trioxymethyl)methylammonium iodide with mercury dioide (2: 1 mol/mol) in acetone. X-ray crystallography shows that the complex consists of two types of crystallographically independent [(HOCH2)3CNH3]+ cations and tetrahedral anions [HgI4]2? (IHgI, 106.49(2)°–113.99(4)°; Hg-I, 2.7849(8)-2.8105(8) Å. [(HOCH2)3CNH3]+ cations are linked via hydrogen bonds O…H-N and O-H…N (O…N, 2.84–2.92 Å) to form polymer chains, which are cross-linked with one another via anions (I…H, 2.81, 2.82 Å). 相似文献
5.
S. Hosein Mousavipour Fatemeh Keshavarz Sara Soleimanzadegan 《Journal of the Iranian Chemical Society》2016,13(6):1115-1124
Quasi-classical trajectory calculations and stochastic one-dimensional chemical master equation simulation methods are used to study the dynamics of the reaction of amidogen radical [NH2(2B1)] with hydroperoxyl radical [HO2(2A″)] on the lowest singlet electronic state. The title complex reaction takes place on a multi-well multichannel potential energy surface consisting of three deep potential wells and one van der Waals complex. In quasi-classical trajectory calculations a new analytical potential energy surface based on CCSD(T)/aug-cc-pVTZ//MPW1K/6-31+G(d,p) ab initio method was driven and used to study the dynamics of the title reaction. In quasi-classical trajectory calculations, the reactive cross sections and reaction probabilities are determined for 200–2000 K relative translational energies to calculate the rate constants. The same ab initio method was used to have the necessary data for solving the one-dimensional chemical master equation to calculate the rate constants of different channels. In solving the master equation, the Lennard-Jones potential model was used to form the collision between the collider gases. The fractional populations of different intermediates and products in the early stages of the reaction were examined to determine the role of the energized intermediates and the van der Waals complex on the dynamics of the title reaction. Although the calculated total rate constants from both methods are in good agreement with the reported experimental values in the literature, the quasi-classical trajectory simulation predicts the formation of NH2O + OH as the major channel in the title reaction in accordance with the previous studies (Sumathi and Peyerimhoff, Chem. Phys. Lett., 263:742–748, 1996), while the stochastic master equation simulation predicts the formation of HNO + H2O as the major products. 相似文献
6.
A. I. Gubanov A. M. Danilenko A. I. Smolentsev N. V. Kuratieva A. B. Venediktov S. V. Korenev 《Journal of Structural Chemistry》2016,57(8):1606-1612
Double complex salts (DCS) α-[Pd(NH3)4][IrF6]·H2O (P21/m, a = 6.3181(3) Å, b = 10.8718(5) Å, с = 7.4526(4) Å, β = 103.568(2)°), β-[Pd(NH3)4][IrF6]·H2O (P21/с, a = 8.5773(3) Å, b = 10.8791(4) Å, с = = 12.6741(3) Å, β = 122.497(2)°), [Pd(NH3)4]3[IrF6]2Cl2·H2O (P-1, a = 7.6080(2) Å, b = 7.6274(2) Å, с = 11.8070(3) Å, β = 122.497(2)°), and [Pd(NH3)4]2[IrF6]NO3 (Fm-3m, a = 11.21210(10) Å) have been synthesized and structurally characterized for the first time. The existence of polymorphs for the DCS has been revealed. The influence of the chemical composition of the initial reagents on the reaction course and, respectively, the products, has been demonstrated. A hypothesis on the influence of the second coordination sphere on the formation of one or the other polymorph of the DCS has been suggested. It has been shown that the series α-[Pd(NH3)4][МF6]·H2O (M = Pt, Pd) exhibits isostructurality. 相似文献
7.
Zongxiao Li Chunlan Yuan 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(8):1332-1335
With the help of the kinetic parameters (the rate constant (k
in
k
p) and the apparent activation energy (E
in
E
p) of the oscillatory induction period and oscillation period) of the oscillating reaction using thirteen amino acids, leucine
(Leu), threonine (Thr), arginine (Arg), lysine (Lys), histidine (His), alanine (Ala), glutamine (Glu), glycine (Gly), methionine
(Met), cystine (Cys), tryptophan (Trp), serine (Ser) and tyrosine (Tyr), as organic substrates in amino acid-BrO3−-Mn2+-H2SO4-acetone system, then based on the Oregonator model and the thermodynamics theory on irreversible process, the thermodynamic
function (ΔH
in, ΔG
in, ΔS
in and ΔH
p, ΔG
p, ΔS
p) of these oscillating system are studied. The results indicate the entropy ΔS of these oscillating reaction are negative, thereby it is proved that the oscillating reaction is a noequilibrium system
with dissipation structure in agreement with the character of the oscillating reaction from disorder to order in irreversible
thermodynamics. These are satisfactorily to explain the experimental phenomena. 相似文献
8.
P. Storoniak M. Kabir J. Błażejowski 《Journal of Thermal Analysis and Calorimetry》2008,93(3):727-732
The enthalpies of formation of PbCl4, PbCl5− and PbCl62−, originating from quantum mechanics, have enabled the thermodynamic behaviour of these ions with respect to Cl-detachment
to be assessed. The stability of salts containing PbCl5− and PbCl62− as a function of the dimensions of these anions and complementary cations was studied using an approach combining the Kapustinskii-Yatsimirskii
equation with basic thermochemical relationships.
It was found that hexachloroplumbates of monovalent metal cations will not dissociate into metal chlorides and PbCl4, provided the complementary cations are suitably large in size. Hexachloroplumbates of divalent metal cations have not yet
been synthesised since no known metal cations attain the requisite large size. Such salts will not dissociate if the divalent
metal cations are able to complex suitably large electron-donating ligands. The pentachloroplumbates of both monovalent and
divalent metal cations are unstable, since no known metal cations have appropriately large ionic radii. The approach adopted
appears to be useful for the examination of the thermal behaviour, stability and reactivity of chloroplumbates. 相似文献
9.
Anjing Wang Junmei He Lingna Kong Naidong Zhang Tong Zheng 《Research on Chemical Intermediates》2017,43(4):2175-2186
This paper investigated the photodegradation characteristics of benzoquinones and benzoquinoneimines. The photosensitivity of benzoquinones and benzoquinoneimines were analyzed by measuring the yield of SO 4 ?· in a light/Fe2+/S2O8 2? system and the degradation mechanism of benzoquinones, then discussed benzoquinoneimines in light/Fe2+/S2O8 2? and light/S2O8 2? system. The results revealed that a more aggressive oxidation of benzoquinones and benzoquinoneimines by the sunlight/Fe2+/S2O8 2? method showed a more rapid and more complete removal of chromaticity than that of the UV/Fe2+/S2O8 2? method. It was showed that they were photosensitizers, and they could generate 1O2 and O 2 ?· which could promote the formation of SO 4 ?· and ·OH in the sunlight system. Nevertheless, for benzoquinones, the sunlight/S2O8 2? method was superior to the UV/S2O8 2? method. For benzoquinoneimines, the sunlight/S2O8 2? method was inferior to the UV/S2O8 2? method. In addition, the yield of SO 4 ?· in the sunlight/Fe2+/S2O8 2? system was more than that of the UV/Fe2+/S2O8 2? system. Therefore, the photosensitivity of benzoquinones is superior to benzoquinoneimines in water treatment. 相似文献
10.
E. M. Glebov V. F. Plyusnin V. P. Grivin A. B. Venediktov S. V. Korenev 《Russian Chemical Bulletin》2007,56(12):2357-2363
Photochemistry of the PtBr6
2− complex in aqueous solution was studied by steady-state and laser flash photolysis (308 nm). The multistep photoaquation
of the complex occurs in the nano-and microsecond time intervals without the formation of intermediate platinum(III) complexes.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2277–2283, December, 2007. 相似文献
11.
S. Menecier S. Valette P. Denoirjean P. Lefort 《Journal of Thermal Analysis and Calorimetry》2012,107(2):607-616
In this article, corrosion of Invar® in a static carbon dioxide atmosphere \( 2\times 1 0^{4} \le P_{{{\text{CO}}_{ 2} }} \le 10^{5} \,{\text{Pa}} \) has been studied between 1163 and 1263 K. At the beginning, after a short initial deceleration for weight gains Δm/S <0.5 mg cm?2, oxidation kinetics were linear up to weight gains of about 4.0 mg cm?2, and only wüstite Fe1?x O was formed with a constant rate r (mg cm?2 s?1) \( r = \frac{{{\text{d}}\left( {\frac{\Updelta m}{S}} \right)}}{{{\text{d}}t}} = 0.41 \times P_{{{\text{CO}}_{ 2} }} \exp \left( {\frac{ - 198000}{RT}} \right) \) where R is the gas constant and t the time (s). Reaction mechanism is similar to that of the pure iron in analogous conditions, with the same rate limiting step i.e. external reaction of CO2 with wüstite and outward diffusion of ions Fe2+ (not limiting). For weight gains Δm/S higher than 4 mg cm?2, the limiting step changes, with an increase of the reaction rate and an internal oxidation. The origin of this mechanism change lies in the microcracks appearing in the oxide during its growth. Then, wüstite is no longer bound to the substrate; outward diffusion of ions Fe2+ stops and a topotactic transformation converts wüstite into magnetite. 相似文献
12.
A. B. Azlarov Kh. M. Polvonov M. K. Askarova S. Tukhtaev 《Russian Journal of Inorganic Chemistry》2011,56(1):124-127
The solubility in the 2Na+,Mg2+‖2Cl−, 2ClO3−-H2O system was studied at 20 and 100°C and the solubility diagrams were plotted. New compounds were not found to form in the
title quaternary reciprocal system. The sodium chloride field was observed to expand with rising temperature. 相似文献
13.
Yu. V. Rakitin V. T. Kalinnikov S. G. Khodasevich V. M. Novotortsev 《Russian Journal of Coordination Chemistry》2007,33(12):891-895
The electronic structures of the complex ions [CuCl4]2? and [CuCl5]3? were analyzed in terms of the extended angular overlap model (AOM) with consideration to sd and pd mixing. The total antibonding orbital energies of these ions show no anomalies in the transition from a tetrahedron to a planar square [CuCl4]2? and from a trigonal bipyramid to a tetragonal pyramid [CuCl5]3?. Presumably, the existence of numerous intermediate forms of these complexes is mainly due to the packing effects rather than the electronic factors. 相似文献
14.
15.
H. Zhao S. Bennici J. Shen A. Auroux 《Journal of Thermal Analysis and Calorimetry》2010,99(3):843-847
The surface acidic properties of sulfated vanadia–titania catalysts prepared by various methods were investigated by adsorption
microcalorimetry, using ammonia as probe molecule. The acidic characteristics of the samples were shown to be strongly affected
by the preparation method, calcination temperature, and sulfur content. The samples prepared by sol–gel and mechanical grinding
exhibited higher acidity than co-precipitated samples. Moreover, increasing the calcination temperature of co-precipitated
samples resulted in a decrease in surface area from 402 to 57 m2 g−1 and sulfur content from around 4 to 0.2 mass%, but up to a certain point generated a stronger acidity. The optimal calcination
temperature appeared to be around 673 K. 相似文献
16.
Inspired by carbo-benzene and its inorganic analogues, in the current work, the viability of extended systems (called carbomers) formed from aromatic small rings was studied. The aluminum aromatic cluster, Al42?, and its isoelectronic carbon analogue, C42+, were employed as starting point. The insertion of alkynyl units into the Al–Al and C–C bonds results in the extended molecules named carbomers. These molecules were compared with the global minima structures, which were searched employing the genetic algorithm program, GEGA. The electronic delocalization (aromaticity) of the isomers was studied with the induced magnetic field (Bind). The results showed that global minimum of C122+ (formed from C42+) was an unexpected diatropic structure which presented a similar magnetic response to the C42+ cluster. Also, optical properties of C122+ were computed. 相似文献
17.
Baoling Wang Liuzheng Sun Haidong Ju Shilong Zhao Degang Deng Huanping Wang Shiqing Xu 《Journal of Sol-Gel Science and Technology》2009,50(3):368-371
CaAl2Si2O8: Eu2+, Mn2+ phosphors have been prepared by a sol–gel method. X-ray diffractometer, spectrofluorometer and UV–Vis spectrometer were used
to characterize structural and optical properties of the samples. The results indicate that anorthite (CaAl2Si2O8) directly crystallizes at 1000 °C in the sol–gel process. CaAl2Si2O8: Eu2+, Mn2+ phosphors show two emission bands excited by ultraviolet light. Blue (around 415 nm) and yellow (around 575 nm) emissions
originate from Eu2+ and Mn2+, respectively. With appropriate tuning of Mn2+ content, CaAl2Si2O8: Eu2+, Mn2+ phosphors exhibit different hues and relative color temperatures. 相似文献
18.
Abstract
First principle density-functional theory calculations have been carried out on the interaction of I− and I3 − with TiO2 anatase surfaces, modeled by finite clusters that range in size from 48 to 180 atoms. The total energy per TiO2 unit and the HOMO-LUMO gaps decrease with increasing the size of the clusters. Both redox species (I− and I3 −) are strongly adsorbed on the TiO2 surface with the adsorbtion of I− being stronger. Adsorption of triiodide leads to its dissociation. The positions of the HOMO and LUMO of the adsorbed systems shift negatively from their respective cluster values. Solvation effects have been modeled using the CPCM model. Introducing solvent reduces the shifting of HOMO and LUMO. Implications for dye-sensitized solar cells (DSSC) are discussed. Both the HOMO-LUMO shifting and the strong adsorption might affect the performance of the cell. 相似文献19.
The kinetics of electroreduction of peroxodisulfate anions on a mechanically renewed silver electrode is studied by voltammetric and impedance methods. Impedance diagrams obtained in the region of negatively charged metal surface are successfully modeled by the equivalent circuit formed by the solution resistance and also the reaction resistance connected in parallel with the constant-phase element substituted for the double layer capacitance. The analysis of experimental data carried out in terms of this circuit and their comparison with the literature data makes it possible to assume that the reduction kinetics of S2O 8 2? anions on this electrode can be adequately described in the framework of the phenomenological theory of slow discharge. The reasons for deviation of the literature data on the kinetics of this reaction on polycrystalline Ag electrode from the relationships following from the slow discharge theory are put forward and substantiated. 相似文献
20.
D. S. Bolotin M. Ya. Demakova E. A. Daines M. S. Avdontseva A. P. Zhdanov K. Yu. Zhizhin N. T. Kuznetsov 《Russian Journal of General Chemistry》2017,87(1):37-43
A series of closo-decaborate anions containing an O-iminoacylamide oxime fragment were synthesized by nucleophilic addition of aromatic amide oximes to 2-propionitrilium closo-decaborate anion. The isolated compounds were characterized by IR, 1H, 13C–{1H}, and 11B–{1H} NMR, and mass spectra. The structure of (Ph4P)[2-B10H9NH=C(Et)ON=C(NH2)C6H4Me-2] was determined by single-crystal X-ray analysis. 相似文献