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1.
Non-isothermal Studies on Mechanism And Kinetics of Thermal Decomposition of Cobalt(II) Oxalate Dihydrate 总被引:1,自引:0,他引:1
B. Małecka E. Drożdż-Cieśla A. Małecki 《Journal of Thermal Analysis and Calorimetry》2002,68(3):819-831
Thermal decomposition of CoC2O4⋅2H2O was studied using DTA, TG, QMS and XRD techniques. It was shown that decomposition generally occurs in two steps: dehydration
to anhydrous oxalate and next decomposition to Co and to CoO in two parallel reactions. Two parallel reactions were distinguished
using mass spectra data of gaseous products of decomposition. Both reactions run according toAvrami–Erofeev equation. For
reaction going to metallic cobalt parameter n=2 and activation energy is 97±14 kJ mol–1. It was found that decomposition to CoO proceeds in two stages. First stage (0.12<αII<0.41) proceeds according to n=2, with activation energy 251±15 kJ mol–1 and second stage (0.45<αII<0.85) proceeds according to parameter n=1 and activation energy 203±21 kJ mol–1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
V. Logvinenko T. Mitkina V. Drebushchak V. Fedin 《Journal of Thermal Analysis and Calorimetry》2011,105(1):103-106
The thermal decomposition of hydrated cucurbit[8]uril C48H48N32O16·20H2O (CB[8]) and the inclusion compound of cucurbit[8]uril with cobalt(III) complex {trans-[Co(en)2Cl2]@CB[8]}Cl·17 H2O was studied in the inert atmosphere by TG, TM, and DSC methods. The dehydration of (C48H48N32O16)·20H2O (at 320–390 K), and the decomposition of cucurbituril itself (at 620–720 K) are accompanied by a decrease in the sample
volume. The inclusion compound loses water molecules at 320–380 K; dehydration is accompanied by an increase in the sample
volume. The decomposition (pyrolisis) of the anhydrous compound takes place at 620–720 K; the decomposition is forestalled
by a continued increase in the sample volume with an endothermic peak (490–600 K), and only the mass loss (620–720 K) is accompanied
by a decrease in the sample volume. The included guest complex does not lose amines until the decomposition process is complete;
the previously observed increase in the sample volume is explained by the expansion of cavitand molecules due to a distortion
of the included [Co(en)2Cl2]+ complex on heating. 相似文献
3.
Zhang J.-J. Wang R.-F. Li J.-B. Liu H.-M. Yang H.-F. 《Journal of Thermal Analysis and Calorimetry》2000,62(3):747-755
The thermal decomposition of Eu2(BA)6(bipy)2 (BA=C2H5N–
2, benzoate; bipy=C10H8N2, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic
parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method,
the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters.
The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)2/3.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn2+,
Co2+, Ni2+, Cu2+
and Zn2+ were obtained as polycrystalline solids
with general formula M(C8H6ClO3)2·nH2O and colours typical for M(II) ions (Mn – slightly pink, Co –
pink, Ni – slightly green, Cu – turquoise and Zn – white).
The results of elemental, thermal and spectral analyses suggest that compounds
of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and
Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate.
The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II)
and Zn(II) heated in air to 1273 K are dehydrated in one step in the range
of 323–411 K and form anhydrous salts which next in the range of 433–1212
K are decomposed to the following oxides: Mn3O4,
CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are
CuO and Cu. The solubility value in water at 293 K for all complexes is in
the order of 10–3 mol dm–3.
The plots of χM
vs.
temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II)
follow the Curie–Weiss law. The magnetic moment values of Mn2+,
Co2+, Ni2+ and Cu2+
ions in these complexes were determined in the range of 76−303 K and
they change from: 5.88–6.04 μB for Mn(C8H6ClO3)2·4H2O, 3.96–4.75
μB for Co(C8H6ClO3)2·5H2O, 2.32–3.02 μB for Ni(C8H6ClO3)2·5H2O and 1.77–1.94
μB for Cu(C8H6ClO3)2·4H2O. 相似文献
5.
Synthesis And Characterization Of Complexes Of Rare Earth Elements With 1,1-Cyclobutanedicarboxylic Acid 总被引:1,自引:0,他引:1
The complexes of yttrium and lanthanide with 1,1-cyclobutanedicarboxylic acid of the formula: Ln2(C6H6O4)3⋅nH2O, where n=4 for Y, Pr–Tm, n=5 for Yb,Lu, n=7 for La, Ce have been studied. The solid complexes have colours typical of Ln3+ ions. During heating in air they lose water molecules and then decompose to the oxides, directly (Y, Ce, Tm, Yb) or with
intermediate formation. The thermal decomposition is connected with released water (313–353 K), carbon dioxide, hydrocarbons(538–598
K) and carbon oxide for Ho and Lu. When heated in nitrogen they dehydrate to form anhydrous salt and next decompose to the
mixture of carbon and oxides of respective metals. IR spectra of the prepared complexes suggest that the carboxylate groups
are bidentate chelating.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
The solubilization of styrene in micelles of the catanionic surfactant dodecyltrimethylammonium hydroxide (DTAOH)–n-dodecane-phosphonic acid (DPA) was studied by UV–Vis. spectrometry, as a function of the DTAOH:DPA proportion in the surfactant
mixture. The styrene molecules are adsorbed at the surface of the micelles, with the vinyl group closer to the hydrocarbon
core than the aromatic ring, which is oriented to the water. In micelles with an excess of DTAOH, the dielectric constant
of the water surrounding the micelles was strongly affected by the non-neutralized –N(CH3)+
3 groups at the Stem layer. In micelles with an excess of DPA, the –PO3H2 groups which are not neutralized by –N(CH3)+
3, remain almost unionized and hydrogen-bonded. The effect of the micellar surface on the surrounding water dielectric constant
dropped sharply. The dielectric constant in the hydrogen-bonded polar layer is ∼65, rising to the value of pure water very
close to the micellar surface.
Received: 2 September 1997 Accepted: 20 October 1997 相似文献
7.
New complexes:Zn(Hsalox)(ox), Zn(Hsalox)(NHPh), Zn(Hsalox)(Hsal) and Zn(Hsalox)2(1,2-diMeim) have been synthesised as a result of a reaction of Zn(salox) and Zn(Hsalox)2 (where: salox
2–=OC6H4CHNO2–, Hsalox
–=OC6H4CHNOH–) with 8-hydroxyquinoline (Hox), o-aminophenol (NH2Ph), o-hydroxybenzoic acid (H2Sal) and 1,2-dimethylimidazole (1,2-diMeim). Chemical, X-ray and thermal analyses of the complexes and their sinters have
been carried out. Thermal decomposition pathways have been postulated for the complexes. The mixtures about not definite composition
have been obtained as a result of a reaction of zinc(o-hydroxybenzaldoximates) with imidazole(Him) and 4-methylimidazole (4-MeHim).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
Bharti U. N. Verma Kingsuk Mukhopadhyay 《Journal of Thermal Analysis and Calorimetry》2011,104(3):1071-1075
The ligand [2-(1,2,3,4-thiatriazole-5-yliminomethyl)-phenol] (L) is a schiff base derived from condensation reaction of 1,2,3,4-thiatriazole-5-ylamine
and Salicylaldehyde. Synthesis of the ligand (L) and the complex [Cu(II)(L)2]·2H2O have been studied in our previous work (Bharti et al., Asian J Chem 23(2):773–776, 2011). Thermal decomposition behavior
of synthesized Cu(II) complex has been investigated by thermo gravimetric (TG) analysis at heating rate of 10 °C min−1 under nitrogen atmosphere. The mechanism of decomposition of Cu(II) complex has been established from TG data. Kinetic parameters
such as order of reaction (n), activation energy (E
a), frequency factor (Z) and entropy of activation (∆S
≠) were calculated by using Freeman and Carroll (J Phys Chem 62:394–397, 1958) as well as Doyle’s methods as modified by Zsako
(J Phys Chem 72(7):2406–2411, 1968). 相似文献
9.
New divalent transition metal 3,5-pyrazoledicarboxylate
hydrates of empirical formula Mpz(COO)2(H2O)2,
where M=Mn, Co, Ni, Cu, Zn and Cd (pz(COO)2=3,5-pyrazoledicarboxylate),
metal hydrazine complexes of the type Mpz(COO)2N2H4
where M=Co, Zn or Cd and Mpz(COO)2nN2H4·H2O,
where n=1 for M=Ni
and n=0.5 for M=Cu
have been prepared and characterized by physico-chemical methods. Electronic
spectroscopic data suggest that Co and Ni complexes adopt an octahedral geometry.
The IR spectra confirm the presence of unidentate carboxylate anion (Δν=νasy(COO–)–νsym(COO–)>215
cm–1) in all the complexes and bidentate
bridging hydrazine (νN–N=985–950 cm–1)
in the metal hydrazine complexes. Both metal carboxylate and metal hydrazine
carboxylate complexes undergo endothermic dehydration and/or dehydrazination
followed by exothermic decomposition of organic moiety to give the respective
metal oxides as the end products except manganese pyrazoledicarboxylate hydrate,
which leaves manganese carbonate. X-ray powder diffraction patterns reveal
that the metal carboxylate hydrates are isomorphous as are those of metal
hydrazine complexes of cobalt, zinc and cadmium. 相似文献
10.
A. I. Kazakov Yu. I. Rubtsov G. B. Manelis L. P. Andrienko 《Russian Chemical Bulletin》1997,46(12):2015-2020
Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide
temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition
of different forms of dinitramide as the acidity of the medium increases: first, N(NO2)− anions, then HN(NO2)2 molecules, and finally, protonated H2N(NO2)2
+ cations. The temperature dependences of the rate constants of the decomposition of N(NO2)− (k
an) and HN(NO2)2 (k′ac) and the equilibrium constant of dissociation of HN(NO2)2 (K
a) were determined:k
an=1.7·1017 exp(−20.5·103/T), s−1,k′ac=7.9·1016 exp(−16.1·103/T), s−1, andK
a=1.4·10 exp(−2.6·103/T). The temperature dependences of the decomposition rate constant of H2N(NO2)2
+ (k
d) and the equilibrium constant of the dissociation of H2N(NO2)2
+ (K
d) were estimated:k
d=1012 exp(−7.9·103/T), s−1 andK
d=1.1 exp(6.4·103/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions
in a wide range of temperatures and acidities of the medium.
In this series of articles, we report the results of studies of the thermal decomposition of dinitramide performed in 1974–1978
and not published previously.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2129–2133, December, 1997. 相似文献
11.
B. Venkateswara Rao 《Journal of Thermal Analysis and Calorimetry》2010,100(2):577-587
Co(II), Ni(II), Cu(II) and Cd(II) chelates with 1-aminoethylidenediphosphonic acid (AEDP, H4L1), α-amino benzylidene diphosphonic acid (ABDP, H4L2), 1-amino-2-carboxyethane-1,1-diphosphonic acid (ACEDP, H5L3), 1,3-diaminopropane-1,1,3,3-tetraphosphonicacid (DAPTP, H8L4), ethylenediamine-N,N′-bis(dimethylmethylene phosphonic)acid (EDBDMPO, H4L5), O-phenylenediamine-N,N′-bis(dimethyl methylene phosphonic)acid (PDBDMPO, H4L6), diethylene triamine-N,N,N′,N′,N″N″-penta(methylene phosphonic)acid (DETAPMPO, H10L7) and diethylene triamine-N,N″-bis(dimethyl methylene phosphonic)acid (DETBDMPO, H4L8) have been synthesised and were characterised by elemental and thermal analyses as well as by IR, UV–VIS, EPR and magnetic
measurements. The first stage in the thermal decomposition process of these complexes shows the presence of water of hydration,
the second denotes the removal of the coordinated water molecules. After the loss of water molecules, the organic part starts
decomposing. The final decomposition product has been found to be the respective MO·P2O5. The data of the investigated complexes suggest octahedral geometry with respect to Co(II) and Ni(II) and tetragonally distorted
octahedral geometry with respect to Cu(II). Antiferromagnetism has been inferred from magnetic moment data. Infrared spectral
studies have been carried out to determine coordination sites. 相似文献
12.
Xuehang Wu Wenwei Wu Shushu Li Xuemin Cui Sen Liao 《Journal of Thermal Analysis and Calorimetry》2011,103(3):805-812
The single phase NH4NiPO4·6H2O was synthesized by solid-state reaction at room temperature using NiSO4·6H2O and (NH4)3PO4·3H2O as raw materials. XRD analysis showed that NH4NiPO4·6H2O was a compound with orthorhombic structure. The thermal process of NH4NiPO4·6H2O experienced three steps, which involves the dehydration of the five crystal water molecules at first, and then deamination,
dehydration of the one crystal water, intramolecular dehydration of the protonated phosphate groups together, at last crystallization
of Ni2P2O7. In the DTA curve, the two endothermic peaks and an exothermic peak, respectively, corresponding to the first two steps’
mass loss of NH4NiPO4·6H2O and crystallization of Ni2P2O7. Based on Flynn–Wall–Ozawa equation, and Kissinger equation, the average values of the activation energies associated with
the thermal decomposition of NH4NiPO4·6H2O, and crystallization of Ni2P2O7 were determined to be 47.81, 90.18, and 640.09 kJ mol−1, respectively. Dehydration of the five crystal water molecules of NH4NiPO4·6H2O, and deamination, dehydration of the crystal water of NH4NiPO4·H2O, intramolecular dehydration of the protonated phosphate group from NiHPO4 together could be multi-step reaction mechanisms. Besides, the thermodynamic parameters (ΔH
≠, ΔG
≠, and ΔS
≠) of the decomposition reaction of NH4NiPO4·6H2O were determined. 相似文献
13.
Thermal behavior of various synthesized transition metal surfactant complexes of the type [M(CH3COO)4]2−[C12H25NH3
+]2 where M: Cu(II), Ni(II), Co(II) has been investigated using Thermogravimetric Analysis (TGA). It was found that pyrolytic
decomposition occurs with melting in metal complexes, and that metal oxides remain as final products. The activation energy
order obtained, E
Cu > E
Ni > E
Co, could be explained on the basis of size of transition metal ion and metal ligand bond strength. In the course of our investigation
on the decomposition of complexes, we carried out a comparative study of different measurement and calculation procedures
for the thermal decomposition. A critical examination was made of the kinetic parameters of non-isothermal thermoanalytic
rate measurement by means of several methods such as Coats–Redfern (CR), Horowitz–Metzger (HM), van Krevelen (vK), Madhusudanan–Krishnan–Ninan
(MKN), and Wanjun–Yuwen–Hen–Cunxin (WYHC). The most appropriate method among these was determined for each decomposition step
according to the least-squares linear regression. It was found that the results obtained using CR method differ considerably
from HM method, as the former method involves a lot of approximations and is not much reliable. The application of thermoanalytic
techniques to the investigation of rate processes has also been discussed. 相似文献
14.
S. I. Nikitenko 《Russian Chemical Bulletin》2000,49(4):649-653
The kinetics of the formation of hydrogen peroxide by the sonolysis of light and heavy water in argon and oxygen atmospheres
was investigated. The sonochemical reaction has a zero order with respect to hydrogen peroxide (H2O2, D2O2, or DHO2). The measurement of the kinetic isotope effect (α), defined as the ratio of the reaction rates in H2O and D2O, carried out under argon gave a value of 2.2±0.3. The observed isotope effect decreases with an increase in the concentration
of light water in H2O−D2O mixtures. No isotope effect is displayed in the oxygen atmosphere (α=1.05±0.10). The isotope effect is determined presumably
by the mechanism of sonochemical decomposition of water molecules, which includes the H2O−Ar* and D2O−Ar* energy exchange (where Ar* are argon atoms in the3P2.0 excited state) in the nonequilibrium plasma generated by a shock wave, arising upon a cavitation collapse.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 645–649, April, 2000. 相似文献
15.
S. V. Goryainov 《Journal of Structural Chemistry》1996,37(1):58-64
This paper reports on the results of temperature studies (20–880°C) of the IR absorption spectra of dioptase crystals in the
range 50–4000 cm−1. During the dehydration of dioptase the state of water changes as follows: (1) initial state, (2) intermediate state with
damped external vibrations of H2O, (3) isolated water molecules with new hydrogen bonds, (4) formation of hydroxyls. The bands of the external virations of
H2O (1) vanish in state (2) because of the formation of vacancies in the six-membered water rings. The frequencies of the translation
vibrations of 6H2O in initial dioptase are close to those in liquid water: 169–170 and 277–290 cm−1. A factor-group analysis of the dioptase vibrations in the space group C
3i
2
is performed. All IR active vibrations 23Au+23Eu are described. The thirty five bands observed in the IR spectra are assigned. The dehydration-induced deformations of the
silicate rings are determined from the shifts of the vibrational bands of Si6O18.
Institute of Mineralogy and Petrography, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 1, pp. 68–74, January–February, 1996.
Translated by I. Izvekova 相似文献
16.
I. S. Ahmed 《Journal of Thermal Analysis and Calorimetry》2006,84(2):405-408
The new bridged diacetato–diamido–diamine–uranyl
complex {2[(UO2)(H2N)(H3N)(OOCCH3)]}
was prepared and characterized by elemental analysis, IR measurement as well
as TG and DTA analysis. The kinetic parameters; activation energy (Ea), pre-exponential factor
(A) and the order of decomposition (n) were calculated from TG curves using Coats–Redfern
and Flynn–Wall–Ozawa methods. The mechanism of decomposition has
been established from TG and DTA data. The data obtained agree quite well
with the expected structure and show that the complex finally decomposes to
form UO3. A general mechanism describing the formation
of bridged complex {2[(UO2)(H2N)(H3N)(OOCCH3)]}
is proposed. 相似文献
17.
Conditions for the formation of rare earth element (Y, La–Lu) 3-methylglutarates were studied and their quantitative composition
and solubilities in water at 293 K were determined (10–2 mol dm–3). The IR spectra of the prepared complexes with general formula Ln2(C6H8O4)3
nH2O (n=3–8) were recorded and their thermal decomposition in the air were investigated. During heating the hydrated 3-methylglutarates
are dehydrated in one step and next anhydrous complexes decompose to oxides Ln2O3 with intermediate formation Ln2O2CO3 (Y, La, Nd–Gd) or directly to the oxides, Ln2O3, CeO2, Pr6O11 and Tb4O7 (Ce, Pr, Tb–Lu).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
Spectral,
magnetic and thermal investigations of some d-electron
element 3-methoxy-4-methylbenzoates
Conditions
for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methoxy-4-methylbenzoates
were investigated and their quantitative composition and magnetic moments
were determined. The IR spectra and powder diffraction patterns of the complexes
prepared of general formula M(C9H9O3)2·nH2O (n=2
for Mn, Co n=1 for Ni, Cu, n=0
for Zn, Cd) were prepared and their thermal decomposition in air was studied.
Their solubility in water at 293 K is of the order 10–2
(Mn)–10–4 (Cu) mol dm–3.
IR spectra of the prepared 3-methoxy-4-methylbenzoates suggest that carboxylate
groups are bidentate bridging. The magnetic moments for the paramagnetic complexes
of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.50, 4.45, 3.16 and 1.79
B. M., respectively. During heating the hydrated complexes lose crystallization
water molecules in one step and then the anhydrous complexes decompose directly
to oxides MO and Mn3O4. Only Co(II) complex decomposes to Co3O4
with intermediate formation CoO. 相似文献
19.
Takayuki Watanabe Narengerile Hiroshi Nishioka 《Plasma Chemistry and Plasma Processing》2012,32(1):123-140
Decomposition of acetone, methanol, ethanol, and glycerine by water plasmas at atmospheric pressure has been investigated
using a direct current discharge. At torch powers of 910–1,050 W and organic compound concentrations of 1–10 mol%, the decomposition
rate of methanol and glycerine was over 99%, while those of acetone and ethanol was 95.4–99%. The concentrations of H2 obtained were 60–80% in the effluent gas for any compounds by pyrolysis. Based on the experimental results, the decomposition
mechanism of organic compounds in water plasmas was proposed and the roles of intermediate species such as CH, CH3, and OH have been investigated; CH radical generated from organic compounds decomposition was easily oxidized to form CO;
incomplete oxidation of CH3 leads to C2H2 generation as well as soot formation; and negligible amount of soot observed from glycerine decomposition even at high concentration
indicated that oxidation of CH×(×:1–3) was enhanced by OH radical. 相似文献
20.
Gh. H. Rounaghi A. Soleamani K. R. Sanavi 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(1-2):43-48
The complexation reactions between Ag+, Hg2+ and Pb2+ metal cations with aza-18-crown-6 (A18C6) were studied in dimethylsulfoxide (DMSO)–water (H2O) binary mixtures at different temperatures using the conductometric method. The conductance data show that the stoichiometry
of the complexes in most cases is 1:1(ML), but in some cases 1:2 (ML2) complexes are formed in solutions. A non-linear behaviour was observed for the variation of log K
f of the complexes vs. the composition of the binary mixed solvents. Selectivity of A18C6 for Ag+, Hg2+ and Pb2+ cations is sensitive to the solvent composition and in some cases and in certain compositions of the mixed solvent systems,
the selectivity order is changed. The values of thermodynamic parameters (ΔH
co, ΔS
co) for formation of A18C6–Ag+, A18C6–Hg2+ and A18C6–Pb2+ complexes in DMSO–H2O binary systems were obtained from temperature dependence of stability constants and the results show that the thermodynamics
of complexation reactions is affected by the nature and composition of the mixed solvents. 相似文献