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1.
V. V. Potekhin 《Russian Chemical Bulletin》2007,56(5):875-882
The oxidation of lower aliphatic alcohols C1–C4 with dioxygen to form the corresponding carbonyl compounds in the presence of the PdII tetraaqua complexes and FeII-FeIII aqua ions in an aqueous medium was studied at 40–80 °C. The introduction of an aromatic compound (acetophenone, benzonitrile,
phenylacetonitrile, o-cyanotoluene, nitrobenzene) and FeII aqua ion instead of the FeIII aqua ion into the reaction system increases substantially the catalytic activity and the yield of the carbonyl compound.
The key role of the Pd species in the intermediate oxidation state stabilized by the aromatic additive in the catalytic cycle
of alcohol oxidation with dioxygen to the carbonyl compound was shown. An increase in the kinetic isotope effect with an increase
in the temperature of methanol oxidation indicates a change in the rate-determining step of alcohol oxidation with dioxygen
in the presence of PdII-FeII-FeIII and the aromatic compound. At temperatures below 60 °C, the catalytically active palladium species are mainly formed upon
the reduction of the PdII tetraaqua complex with the FeII aqua ion, whereas at higher temperatures the reaction between the alcohol and PdII predominates. The mechanism and kinetic equation of the process were proposed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 842–848, May, 2007. 相似文献
2.
V. N. Leibzon L. V. Michalchenko M. Yu. Leonova V. P. Gultyai 《Russian Chemical Bulletin》2005,54(5):1203-1207
Small additives of iron(II) or copper(II) salts change the regioselectivity of 2,4,6-trinitrotoluene monoreduction with titanium(III) chloride affording predominantly less accessible 2-amino-4,6-dinitrotoluene over 4-amino-2,6-dinitrotoluene (from 25% when
the reduction occurs in the absence of the iron and copper salts to 70% in the presence of these salts). A possible mechanism
of the process is discussed.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1172–1176, May, 2005. 相似文献
3.
Kinetics of hydrogen peroxide decomposition in the presence of the tetraaquapalladium(II) complex in an aqueous solution at
40–70 °C was studied. The reaction rate is the first order with respect to the concentration of both PdII and H2O2 and the negative first order with respect to perchloric acid. Using free radicals traps, the reaction mechanism was found
to differ from the traditional free-radical mechanism known for d-metal aqua ions and proceeds without generation of hydroxyl
radicals. The kinetic data obtained suggest a mechanism involving the formation of an intermediate palladium complex with
oxygen.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1077–1082, May, 2005. 相似文献
4.
Critical phenomena in ethylbenzene oxidation in an acetic acid solution at high cobalt(III) concentrations (from 0.01 to 0.2 mol L−1) were studied at 60–90 °C by the gasometric (O2 absorption), spectrophotometric (CoIII accumulation), and chemiluminescence (relative concentration of radical RO2
·) methods. These phenomena are as follows: (1) increase in the oxidation rate above the theoretical limiting rate of radical
autooxidation (k
3
2[RH]2/2k
6); (2) achievement of a maximum and a sharp decrease in the oxidation rate and concentration of radical RO2
· with the further increase in the CoII concentration (existence of critical concentrations). The oxidation rate increases due to the reaction RO2
· + CoII + H+ → → ROOH + CoIII, while the inhibition effect is caused by the decay of RO2
· radical involving two cobalt(II) atoms: RO2
· + 2 CoII → R′CO + CoIII + CoII (k(70 °C) ≈ 300 L2 mol−2 s−1). The detailed scheme (through the formation of the complex RO2
·CoII) describing the conjugation of these reactions was proposed.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1823–1827, August, 2005. 相似文献
5.
V. V. Potekhin 《Russian Journal of General Chemistry》2007,77(9):1593-1597
Oxidation of metallic Pd(0) particles applied onto an oxide support with Fe(III) ions in a concentration not exceeding 0.06 M at 70°C was studied. In contrast to palladium black, with the supported catalyst Pd/ZrO2 Pd(II) is formed in the solution in the concentration corresponding to the thermodynamic equilibrium. With an increase in the initial Fe(III) concentration, the equilibrium yield of Pd(II) increases. The initial reaction rate grows with an increase in the weight of the initial Pd-containing catalyst and in the initial Fe(III) concentration. The revealed kinetic relationships of the dissolution of Pd(0) in the reaction with Fe(III) aqua ions allow a conclusion that, in oxidation of lower olefins C2-C4 in the catalytic system Fe(III)_Pd/ZrO2 in aqueous solution, Pd(II) is regenerated in the catalytic cycle by oxidation of Pd(I) species, rather than of Pd(0), with Fe(III) aqua ions. 相似文献
6.
The behavior of the metals in the Pt−Pd/ZrO2 and Pt−Pd/SO4/ZrO2 systems was studied by DRIFT spectroscopy. After reduction of Pt−Pd/ZrO2 at 100 °C, the states of the metals are mainly Pt0 and Pd0 with a minor admixture of positively charged forms of Pt+ or Pd2+. An increase in the temperature of reduction leads to the formation of a bimetallic alloy. In the Pt−Pd/SO4/ZrO2 system, the effects of alloy formation and the interaction of the surface SO4 groups superimpose. At low reduction temperatures, the surface SO4 groups interact mainly with palladium. The influence of the surface sites on both supported metals increases with increasing
reduction temperature.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1265–1270, July, 1999. 相似文献
7.
The kinetics of oxidation of ethene, propene, and 1-butene with Fe(III) aqua ions to the corresponding carbonyl compounds in the presence of the 1% Pd/ZrO2/SO4 precatalyst in aqueous perchloric acid at 40–80°C was studied. The oxidation rate increases in the order C2H4 < C4H8 < C3H6 and with increasing catalyst weight and in the acid and Fe(III) concentrations; it is independent of the olefin pressure. The ethene oxidation rate is described by the Michaelis-Menten equation. In the case of 1-butene, the reaction is accompanied by migration of the double bond with the formation of 2-butene. 相似文献
8.
K. L. Tokarev M. A. Kiskin A. A. Sidorov G. G. Aleksandrov V. N. Ikorskii I. P. Suzdalev V. M. Novotortsev I. L. Eremenko 《Russian Chemical Bulletin》2008,57(6):1209-1214
The mononuclear complexes (η3-terpy)M(Piv)2·MeCN (M = Fe
ii
(3) and Co
ii
(4), and Piv is the pivalate anion) were synthesized by the reactions of polymeric iron(ii) and cobalt(ii) pivalates with 2,2′:6′,2″-terpyridine (terpy). The oxidation of compound 3 affords the pentanuclear heterospin iron(ii,iii) complex (η3-terpy)Fe5(μ4-O)(μ3-OH)(μ-OH)2(μ-Piv)7(η1-Piv)2 (5). All compounds were characterized by X-ray diffraction.
Dedicated to the 90th anniversary of the L. Ya. Karpov Institute of Physical Chemistry.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1186–1190, June, 2008. 相似文献
9.
A. V. Ivanov E. G. Khelkovskaya-Sergeeva T. V. Vasina O. V. Masloboishchikova L. M. Kustov P. Zeuthen 《Russian Chemical Bulletin》1999,48(7):1266-1269
The catalytic activity of superacidic systems based on SO4/ZrO2 and modified by IV Period metals in isomerization ofn-butane was studied. At low temperatures of the reaction, the introduction of Fe3+, Sc3+, Co2+, or Zn2+ ions (1%) increases the yield of isobutane by 1.5 times due to the activation ofn-butane on the sites created by the promoting ions. The addition of Cr3+, V4+, or Mn2+ (1%) decreases the catalytic activity because of a decrease in the catalyst acidity, most likely, due to the reduction of
surface sulfur species. The influence of the nature of the support and surface additives of SiO2, TiO2, and ZrO2 on the activity and selectivity of the catalytic system inn-butane isomerization was studied.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7 pp. 1276–1280, July, 1999 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.
The mutual influence of the atoms on the composition of solid fluorine-containing antimony(iii) complexes formed in aqueous solutions in the (MF)
x
−(M′F)
n−x
−SbF3 (M, M′=Na, K, Rb, Cs, and NH4;n=1, 2;x=0 to 2), (KNO2)
n
−(KY)
n
−SbF3 (Y=F, Cl, SO4;n=0.5, 1), and K2SbF5−K2SbCl5 systems was investigated by elemental, X-ray, and thermogravimetric analyses and by IR and121,123Sb NQR spectroscopy. The isomorphism conditions for fluorine-containing antimony(iii) compounds resulting in the formation of complexes NaM′SbF5·1.5H2O (M′=K and Rb), K2SbF5·1.5H2O, NaCs3Sb4F16·H2O, KsbF3Cl, K2SbF2Cl3 with constant compositions, continuous M
x
M′2−x
SbF5 (0<x<2) and limited M
x
M′1−x
SbF4 (0.25<x<0.75; M, M′=K, Rb, Cs, and NH4) solid solutions or LiF+MSbF4 (M=Na, K, Rb, and Cs), M2SbF5+Cs2SbF5 (M=Na and K) and MSbF4+NaSbF4 (M=Rb and NH4) mechanical mixtures were determined.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 103–108, January, 1999. 相似文献
12.
Binuclear nitrosopalladium complexes Pd2(μ-COOR)2(η2-CH2C6H4NO)2 (R = Me, CF3, or Ph) were studied by ESR spectroscopy. Analysis of parameters of ESR spectra of the polycrystalline samples and their
toluene solutions suggests partial izomerization of the nitroso ligands to the nitroxide form to result in the oxidation of
palladium(II) to palladium(III).
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Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1746–1751, August, 2005. 相似文献
13.
The influence of surfactants (anionic and cationic) on the reactivity of the redox couple cerium(IV) and D-glucose was examined spectrophotometerically. Various kinetic parameters have been determined in the absence and presence of surfactants. The kinetics were followed by monitoring the disappearance of the absorbance of cerium(IV) at 385 nm. The reaction obeyed first-order kinetics with respect to [D-glucose] in both media. No effect of anionic micelles of sodium dodecyl sulfate (SDS) was observed due to electrostatic repulsion between the negative head group of SDS and reactive species of cerium(IV) (Ce(SO4)
3
2−
). A twofold increase in the oxidation rate was observed in the presence of cationic micelles of cetyltrimethylammonium bromide (CTAB). The observed catalytic role has been analyzed in terms of the Menger–Portnoy model. The effects of various inorganic salts (Na2SO4, NaNO3 and NaCl) were also studied in micellar media. 相似文献
14.
Substitution inertcis-diaqua CrIII complexes: cis-[(Lx−)CrIII(H2O)2](3−x)+ derived from N-donor ligands (Lx−) viz., bipyridine and 1,10-phenanthroline (x = 0) and N,O-donor ligands viz., nitrilotriacetate and anthranilate N,N-diacetate
(x = 3) titrate as diprotic acids in aqueous solution and enhance the acidity of otherwise weakly acidic boric acid (H3BO3) producing mononuclear and binuclear mixed ligand CrIII-borate complexes: [(L)Cr(H2BO4)]x− and [(L)Cr(BO4)Cr(L)](1−2x)+ respectively through coordination of the H2O and/or OH− ligands, cis-coordinated in the CrIII-complexes on the electron deficient BIII-atom in H3BO3 with release of protons. Deprotonation of the parent CrIII-complexes and their reactions with H3BO3 have been investigated by potentiometric method in aqueous solution,I = 0.1 mol dm−3 (NaNO3) at 25 ±0.1°C. The equilibrium constants have been evaluated by computerized methods and the tentative stoichiometry of the
reactions have been worked out on the basis of the speciation curves 相似文献
15.
The enthalpies of dissolution of glycine (Gly) and L-α-alanine (Ala) in water at 288.15–318.15 K were measured. The results were compared with the earlier obtained data for L-α-phenylalanine (Phe) and L-α-histidine (His). The standard enthalpies of dissolution (Δsoln
H
0) and differences (ΔC
p
0
) between the limiting partial molar heat capacity of the amino acids in solution and the heat capacity of the amino acids
in the crystalline state
were calculated in the temperature interval 273–373 K. Changes in the entropy of dissolution (ΔΔsoln
S
0) and reduced Gibbs energy [Δ (Δsoln
G
0/T)] in the temperature interval from 273 to 373 K were determined from the known thermodynamic relationships. The ΔC
p
0
value is negative for hydrophilic glycine and positive for other amino acids. The ΔΔsoln
S
0 values increase with an increase in the hydrophobicity of the amino acids. The Δ(Δsoln
G
0/T) values become more negative in the order Ala, Phe, Gly, His.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 711–714, April, 2007. 相似文献
16.
M. Mazloum Ardakani A. Talebi H. Naeimi M. Nejati Barzoky N. Taghavinia 《Journal of Solid State Electrochemistry》2009,13(9):1433-1440
A carbon paste electrode, modified with 2, 2′-[1,7-hepthandiylbis(nitriloethylidyne)]-bis-hydroquinone and TiO2 nanoparticles, was used for the simultaneous determination of dopamine (DA), uric acid (UA), and l-cysteine. The study was carried out by using cyclic voltammetry, chronoamperometry, and square wave voltammetry (SWV) techniques.
Some kinetic parameters such as the electron transfer coefficient (α) and heterogeneous rate constant (ks) were also determined for the DA oxidation. A dynamic range of 8.0–1400 μM, with the detection limit of 8.4 × 10−7 M for DA, was obtained using SWV (pH = 7.0). The prepared electrode was successfully applied for the determination of DA,
UA, and l-cysteine in real samples. 相似文献
17.
I. P. Romanova S. G. Fattakhov A. A. Nafikova I. I. Vandyukova R. R. Shagidullin N. M. Azancheev V. S. Reznik O. G. Sinyáshin 《Russian Chemical Bulletin》1998,47(9):1812-1819
The reactions of phosphine derivatives of diallyl isocyanurates with palladium(ii) dichloride lead to the formation of complexes, whose structure, composition, and stability depend on the length of the methylene
chain between the isocyanurate and diphenylphosphine fragments in the ligand. 1,3-Diallyl-5-[5′-(diphenylphosphino)pentyl
and 10′-(diphenyl-phosphino)decyl] isocyanurates with PdCl2 form monomeric L2PdCl2
trans-complexes in which P atoms of the ligands participate in coordination with the metal. 1,3-Diallyl-5-[2′-(diphenylphosphino)ethyl]
isocyanurate with PdCl2 forms a dimeric (LPdCl2)2 complex, which decomposes in a solution to the monomer including solvent molecule into the coordination sphere of the metal.
The reactions of 1,3-diallyl-5-[4′-(diphenylphosphino)butyl] isocyanurate and 1,3-diallyl-5-[6′-(diphenylphosphino)hexyl]
isocyanurate with PdCl2 give monomeric chelate LPdCl2 complexes in which one of the allyl groups of the isocyanurate cycle participates in coordination with the central ion along
with the phosphorus atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1859–1865, September, 1998. 相似文献
18.
Shuliang Xu Lixia Wang Wenling Chu Weishen Yang 《Journal of molecular catalysis. A, Chemical》2009,310(1-2):138-143
The effects of palladium precursors (PdCl2, (NH4)2PdCl4, Pd(NH3)2Cl2, Pd(NO3)2 and Pd(CH3COO)2) on the catalytic properties in the selective oxidation of ethylene to acetic acid have been investigated for 1.0 wt% Pd–30 wt% H4SiW12O40/SiO2. The structures of the catalysts were characterized using X-ray diffraction, N2 adsorption, H2-pulse chemical adsorption, infrared spectrometry of the adsorbed pyridine, H2 temperature-programmed reduction and X-ray photoelectron spectroscopy. The present study demonstrates that the different palladium precursors can lead to the significant changes in the dispersion of palladium. It is found that Pd dispersion decreases as follows: PdCl2 > (NH4)2PdCl4 > Pd(NO3)2 > Pd(NH3)2Cl2 > Pd(C2H3O2)2, which is nearly identical to the catalytic activity. This indicates that the dispersion of palladium plays an important role in the catalytic activity. Furthermore, density of Lewis (L) and Brönsted (B) acid sites are also strongly dependent on the palladium precursors. It is also demonstrated that an effective catalyst should possess a well combination of Brönsted acid sites with dispersion of palladium. 相似文献
19.
T. N. Rostovshchikova M. S. Korobov D. A. Pankratov G. Yu. Yurkov S. P. Gubin 《Russian Chemical Bulletin》2005,54(6):1425-1432
Nanosized iron oxides stabilized on the surface of ultradispersed poly(tetrafluoroethylene) (UPTFE) granules were synthesized
by the thermal destruction of iron formate in boiling bed of UPTFE on the surface of heated mineral oil. The particle size
of nanoparticles (∼6 nm) containing 5, 10, and 16 wt.% Fe depends weakly on the temperature of synthesis and iron to polymer
ratio. The metal state is determined by the synthesis conditions. The nanoparticles synthesized at 280 °C consist mainly of
the Fe3O4 and Fe2O3 phases. The samples obtained at 320 °C also contain iron(II) oxide. The catalytic properties of the obtained samples were tested in dichlorobutene isomerization. Unlike isomerization
on the iron oxide nanoparticles supported on silica gel, reaction over the UPTFE supports proceeds without an induction period.
The sample with 10 wt.% Fe containing magnetically ordered γ-Fe2O3 nanoparticles possesses the highest catalytic activity. Fast electron exchange between the iron ions in different oxidation
states and high defectiveness of the nanoparticles contribute, most likely, to the catalytic activity.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1383–1390, June, 2005. 相似文献
20.
Wu Feng Deng Nansheng E. M. Glebov I. P. Pozdnyakov V. P. Grivin V. F. Plyusnin N. M. Bazhin 《Russian Chemical Bulletin》2007,56(5):900-903
The formation of MV•+ radical cations was observed upon the laser flash photolysis of the iron(III) tartrate complex [FeIIITart]+ (1) in the presence of methyl viologen (MV2+). The rate constants of the reactions involving MV•+ were measured. The intramolecular electron trans-fer to form FeII and escape of the organic radical to the solvent bulk upon the photolysis of 1 were proposed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 866–869, May, 2007. 相似文献