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1.
Yu. I. Rubtsov A. I. Kazakov E. Yu. Rubtsova L. P. Andrienko G. B. Manelis 《Russian Chemical Bulletin》1998,47(1):32-38
The kinetics of the heat release during the reactions of aqueous HNO3 withn-heptane andn-octadecane was studied. The kinetic regularities of the reactions of hydrocarbons C7H16−C18H38 with HNO3 and the heats of the reactions were described. At all stages, except initial, the hydrocarbon reacts with NO2 and nitric acid reproduces NO2 in the reaction with NO. The accumulation of NO2 results in the acceleration of the process. When the pressure of the hydrocarbon vapor is equilibrium, its reaction with
NO2 can also proceed in the gas phase. The contribution of this reaction to the total heat release was estimated. The additives
of aromatic and unsaturated hydrocarbons to aliphatic hydrocarbons increase strongly the initial rate of the heat release
and changes slightly the subsequent stages of the process. Naphthenic hydrocarbons have almost no effect on the kinetic parameters
of the process.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 35–40, January, 1998. 相似文献
2.
S. D. Razumovsky V. N. Gorshenev A. L. Kovarskii A. N. Shchegolikhin 《Russian Chemical Bulletin》2008,57(9):1806-1810
The kinetics of ozone sorption by powders of finely milled graphite at 20 °C, the behavior of unpaired electrons of the conjugated
systems of the structure, and the IR spectra of the surface functional groups were studied. The surface hexagonal cells enter
into the reaction. After 1/6 of the accessible cells was consumed, the reaction rate decreased appreciably, most likely, due
to the induction effects of the functional groups formed. Considerable weight losses of the samples were observed during the
reaction. The changes in the character of the ESR spectra indicate a decrease in the sizes of the conjugation ensembles. The
reaction of ozone with the surface produces local sites of structure destruction, which decrease the reactivity of the adjacent
surface regions and thus protect them from further destruction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1772–1776, September, 2008. 相似文献
3.
E. V. Avzyanova N. N. Kabalnova V. V. Shereshovets 《Reaction Kinetics and Catalysis Letters》1995,56(1):213-218
The kinetics of conversion of ozone complexes with a series of substituted benzene ArX.O3 (ArX=C6H5CH3, C6H5C2H5, C6H5CH(CH3)2, C6H5C(CH3)3, C6H5F, C6H5Cl,m-BrC6H4CH3, C6H5CH2Cl have been studied by spectrophotometry. The rate of ArX.O3 consumption in CH2Cl2-ArX solutionis W=k0 [ArX. O3]+k1 [ArX. O3] [ArX]. 相似文献
4.
Solutions of 1-adamantanol in sulfuric acid at T < 100 °C interact with alkanes (RH, [H2SO4] > 85%) and arenes (ArH, [H2SO4] > 59%). The data on the kinetics, kinetic isotope effect (KIE), effects of the structure of RH and ArH and acidity of the
medium, and the observation of 1,4-cis-dimethylcyclohexane isomerization indicate that adamanyl cations (Ad+) serve as reactive species. In the reactions with alkanes, the Ad+ cation abstracts the hydride ion from RH in the rate-determining step. Compensation dependences appear between the activaion
parameters for the KIE and “effect 5/6” (ratio of the rate constants for the C–H bond cleavage in cyclopentane and cyclohexane)
in the reactions of cycloalkanes with Ad+ and other electrophilic reagents, such as “anthracene” (An2)H+ and hydroxymethyl (CH2OH)+ cations and HgII ions, including the points of the lower selectivity limit (k
H/k
D) = 1.4, (“5/6”) = 1. In the reactions with the Ad+ cation, the bond selectivity 30: 20 of alkanes is higher, while 20: 20 is lower compared to other reagents. In the first case, the selectivity is probably determined predominantly by the energies
of the cleaved C–H bonds, whereas in the second case it is determined by steric hindrances. Judging by the kinetic and selectivity
data in the series benzene—toluene—o-xylene—m-xylene and the absence of the reaction with p-xylene, mesitylene, and pseudocumene, it can be concluded that the main contribution to the Ad+ + ArH interaction is made by adamantylation to the para- and meta-positions of the benzene ring, whereas the ortho-positions are inaccessible to the attack because of steric hindrances.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1581–1596, August, 2008. 相似文献
5.
6.
Kinetic calculation for the reaction of H with Si_2H_6 using the variational transition state theory
The reaction of disilane with atomic hydrogen has been studied. This reaction involves both substitution and abstraction. Calculations show that the hydrogen abstraction is the strongest competing channel. The canonical variational transition state theory with a small curvature tunneling correction (SCT) has been used for the kinetic calculation. The theoretical results are in good agreement with the available experimental data. Comparing the reactions of atomic hydrogen with disilane and silane, it can be seen that the reactivity of the Si-H bond is higher in Si2H6than that in SiH4. 相似文献
7.
G. M. Abushakhmina N. N. Kabalnova S. S. Zlotsky V. V. Shereshovets D. L. Rakhmankulov 《Reaction Kinetics and Catalysis Letters》1999,67(2):289-294
Kinetic regularities of the reactions of dimethyldioxirane (1) with 1,3-dioxolane, 2-propyl-1,3-dioxolane, 2-i-propyl-1,3-dioxolane,
2-phenyl-1,3-dioxolane, and 2,2-pentame-thylene-1,3-dioxolane (RH) in acetone have been studied spectrophotometrically in
the temperature range from 15 to 48°C. The reaction rate d[1] /dt=k[1]·[RH] does not depend on the oxygen concentration in
the reaction mixture. The activation parameters in the reaction with 1,3-dioxolane have been determined: lgk=(5.13±0.6)−(10.07±0.82)/Q,
where Q=2,303 RT kcal/mol. 相似文献
8.
Molecular complexes of phenols with DDQ have been studied spectrophotometrically in the temperature range of 10–30‡C in a
solvent (CHC13) of low polarity under low donor concentrations. All the complexes exhibit one CT band each in the wavelength region where
acceptor and donor do not have any absorption. The complexes are inferred to be of the π2π type and have Ry configuration in which the donor molecular orbital encompasses the substituent. The ionization potentials of the donors,
the stability constants and thermodynamic parameters of the complexes have been evaluated. 相似文献
9.
Boga C Del Vecchio E Forlani L Goumont R Terrier F Tozzi S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(34):9600-9607
Reactions of DNBF with a series of 2-aminothiazoles (1 a-f) to afford thermodynamically stable C-bonded sigma-adducts have been investigated in acetonitrile. A most significant finding emerged on recording NMR spectra immediately after mixing of equimolar amounts of DNBF and the unsubstituted 2-aminothiazole (1 a) in Me2SO: namely, that the formation of 9 a is preceded by that of a short-lived intermediate species X. From the 1H NMR parameters characterizing this intermediate, as well as the dependence of its lifetime on the experimental conditions-the presence of excess DNBF over 1 a increases the lifetime of X while an excess of base (1 a) accelerates its conversion into 9 a--it is convincingly demonstrated that the structure of X combines the presence of a positively charged Wheland complex moiety (with regard to the thiazole ring) with that of a negatively charged Meisenheimer complex moiety (with regard to the benzofuroxan system). So far, only one intermediate of this type (noted WM) has been successfully characterized, in the reactions of DNBF with 1,3,5-tris(N,N-dialkylamino)benzenes. Among the key features supporting the intermediacy of X along the reaction coordinate leading to 9 a is the fact that the reactions of DNBF with 1 a in the presence of an alcohol (MeOH, EtOH, nPrOH) produce new adducts arising from the addition of an alcohol molecule to the thiazole moiety of WM-1 a. Reflecting the presence of three chiral centres, these species are formed as mixtures of several diastereomers that could all be characterized in their racemic forms in ethanol. These findings generalize the previous report on the formation of Wheland-Meisenheimer carbon-carbon complexes in homocyclic series. 相似文献
10.
Yunju Zhang Jingyu Sun Wanqiao Zhang Yizhen Tang Rongshun Wang 《Journal of computational chemistry》2014,35(22):1646-1656
The reaction of propargyl alcohol with hydroxyl radical has been studied extensively at CCSD(T)/aug‐cc‐pVTZ//MP2/cc‐pVTZ level. This is the first time to gain a conclusive insight into the reaction mechanism and kinetics for this important reaction in detail. Two reaction mechanisms were revealed, namely addition/elimination and hydrogen abstraction mechanism. The reaction mechanism confirms that OH addition to C?C triple bond forms the chemically activated adducts, IM1 (·CHCOHCH2OH) and IM2 (CHOH·CCH2OH), and the hydrogen abstraction pathways (? CH2OH bonded to the carbon atom and alcohol hydrogen) may occur via low barriers. Harmonic model of Rice–Ramsperger–Kassel–Marcus theory and variational transition state theory are used to calculate the overall and individual rate constants over a wide range of temperatures and pressures. The calculated rate constants are in good agreement with the experimental data. At atmospheric pressure with Ar as bath gas, IM1 (·CHCOHCH2OH) and IM2 (CHOH·CCH2OH) formed by collisional stabilization are dominant in the low temperature range. The production of CHCCHOH + H2O via hydrogen abstraction becomes dominate at higher temperature. The fraction of IM3 (CH2COHCH2·O) is very significant over the moderate temperature range. © 2014 Wiley Periodicals, Inc. 相似文献
11.
12.
S. A. Grabovskiy E. A. Markov A. B. Ryzhkov N. N. Kabal’nova 《Russian Chemical Bulletin》2006,55(10):1780-1787
The products and kinetic regularities of thermal decomposition of ethyl(methyl)dioxirane (EMD) were studied. The consumption
of EMD occurs via four parallel pathways: two isomerizations to ethyl acetate and methyl propionate, solvent oxidation via insertion of the oxygen atom into the C-H bond of a solvent molecule (butanone), and hydrogen atom abstraction from the solvent
by dioxirane with radical escape from the cage. The contribution of the latter route to the oxidation of butan-2-one at 35
°C is 43%. Alkyl radicals initiate EMD decomposition in an inert atmosphere. The activation parameters of EMD isomerization
to esters and the reaction of EMD with butanone were determined. The isomerization of EMD was studied by the DFT method. The
geometric parameters were optimized at the UB3LYP level using the 6-31G** and/or 6-311+G** basis sets. The calculated energies
were corrected taking into account zero-point vibrations. The theoretical results are in good agreement with experimental
data. The mechanism of EMD thermolysis is considered.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1716–1723, October, 2006. 相似文献
13.
Intramolecular stacking interaction in mixed-ligand complexes containing ATP4- and aromatic N-heterocyclic ligands 总被引:1,自引:0,他引:1
The stability constants of the binary ML2+ and ternary M(ATP)L2- complexes,where L=Iq (isoquinoline) or BIm (benzimidazole) and M=Zn2+ or Cd2+,have been determined by poten-tiometric pH titration in aqueous solution at I=0.1 mol/L (NaClO4),T=25℃.The stability of the ternary complexes characterized by corresponding to the equilibrium M(ATP)2-+ML2+=M(ATP)L2-+M2+ is higher than what would be expected on statistical grounds.The increase may be related to the stacking interaction between the aromatic ring of the ligands L and the purine moiety of ATP4- 1H NMR studies of Zn2+/ATP4-/L confirm the presence of stacking in the ternary complexes.It is concluded that the strength of the intramolecular stacking interaction is dependent on the structure of the aromatic ring of the ligand L and the formation of a metal ion bridge.Possible implications are discussed briefly. 相似文献
14.
T. L. Rakitskaya A. S. Truba L. A. Raskola A. Yu. Bandurko A. A. Golub 《Theoretical and Experimental Chemistry》2006,42(1):60-66
We describe the composition, structure, and catalytic activity in the reaction of ozone decomposition for copper(II) complexes
with acido ligands and immobilized Schiff’s bases (propyl benzaldimine derivatives) that are anchored on silica (silica gel,
aerosil). We demonstrate methods for controlling their catalytic activity.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 55–60, January–February, 2006. 相似文献
15.
Direct dynamics study on the reaction of acetaldehyde with ozone 总被引:1,自引:0,他引:1
The hydrogen abstraction reaction of ozone with acetaldehyde has been studied theoretically over the temperature range 250-2500 K. Two different reactive sites of acetaldehyde molecule, CH(3) and CHO groups have been investigated, and results confirm that the CHO group is a highly reactive site. In this study, the geometries and harmonic vibrational frequencies of all stationary points are calculated at the MPW1K, BHandHLYP, and MPWB1K levels of theory. The minimum energy paths (MEPs) were obtained at the MPW1K/6-31+G(d,p) level of theory. To refine the energies along the MEPs of each channel, single-point energy calculations were performed by a higher-level energy calculation method (denoted as HL). The rate constants were evaluated based on the MEPs from the HL method in the temperature range 250-2500 K by using the conventional transition state theory (TST), the canonical variational transition state theory (CVT), the microcanonical variational transition state theory (muVT), the CVT coupled with small-curvature tunneling (SCT) correction (CVT/SCT), and the muVT coupled with Eckart tunneling correction (muVT/Eckart). The fitted three-parameter Arrhenius expressions of the calculated CVT/SCT and muVT/Eckart rate constants of the H abstraction from CHO group are k CVT/SCT(T) = 4.92 x 10(-27).T 3.77.e(-7867.0/T) and k muVT/Eckart(T) = 2.10 x 10(-27).T(3.90).e(-7706.2/T), respectively. The fitted three-parameter Arrhenius expressions of the calculated CVT/SCT and muVT/Eckart rate constants of the H abstraction from CH3 group are k(CVT/SCT)(T) = 1.27 x 10(-27).T(3.94).e(-14554.1/T) and k muVT/Eckart(T) = 1.62 x 10(-26).T(3.66).e(-15459.8/T), respectively. 相似文献
16.
Zhengcheng Wen Zhihua Wang Jiangrong Xu Junhu Zhou Kefa Cen 《International journal of quantum chemistry》2011,111(5):1081-1091
Despite of its fundamental importance, the mechanism of the reaction between ozone and dioxins are still lack detailed investigation so far. It is well-known that quantum chemical calculation is a well-established method for investigating chemical reactions. In this article, quantum chemical calculation was employed to investigate the mechanism of the reaction between ozone and dioxins, as exemplified by 2,3,7,8-TCDD. The theoretical study showed that, 2,3,7,8-TCDD was gradually destructed by ozone via six cleavages of the CC bonds. All the six cleavages of the CC bonds were calculated and discussed in detail based on the theoretical calculations by the UB3LYP/6-31G(d) method. At the same time, the energies of stationary points along the reaction process were calculated by the UMP2/6-311g(d,p)//UB3LYP/6-31G(d) method and the activation energy was obtained. The obtained activation energy was 12.25 kcal/mol, which was lower than that of the reaction between benzene and O3(16.64 kcal/mol). This indicated that, by comparison with benzene, 2,3,7,8-TCDD could be more efficiently destructed by O3. The reason for this result was also discussed. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
17.
Mono-, di-, and tetraiodothiacalix[4]arenes 13-16 have been successfully synthesized for the first time by the Griess reaction of diazonium salts of the corresponding aminothiacalix[4]arenes 4-7. X-ray crystallography reveals that monoiodinated compound 13 adopts a distorted pinched cone conformation, in which the three hydroxy groups and the iodine atom form a pseudo-cyclic hydrogen bonding. On the other hand, tetraiodinated compound 16 adopts a 1,3-alternate conformation presumably due to the steric hindrance and dipole repulsion between the iodine atoms. 相似文献
18.
19.
The reaction of disilane with atomic hydrogen has been studied. This reaction involves both substitution and abstraction.
Calculations show that the hydrogen abstraction is the strongest competing channel. The canonical variational transition state
theory with a small curvature tunneling correction (SCT) has been used for the kinetic calculation. The theoretical results
are in good agreement with the available experimental data. Comparing the reactions of atomic hydrogen with disilane and silane,
it can be seen that the reactivity of the Si-H bond is higher in Si2H6 than that in SiH4. 相似文献
20.
Rajiv Kumar S. P. Tripathi G. K. Chaturvedi 《Monatshefte für Chemie / Chemical Monthly》1984,115(3):283-288
Mixed-ligand ternary complexes of La(III), Pr(III), Nd(III), Gd(III), and Dy(III) with iminodiacetic acid (IMDA) and citraconic (CCA) or maleic acid (MIA), have been studiedpH-metrically. Their formation takes place through the stepwise addition of the secondary ligand (IMDA) to the initially formed 1:1, Ln(III)—CCA/MIA binary species. The resulting ternary complexes undergo hydrolysis to form their hydroxo derivatives simultaneously. The stability constants of the hydroxo species are calculated for constant temperature (27 ± 1°C) and ionic strength (I=0.1M KNO3). The relative order of stability is: La(III)
Gleichgewichtsuntersuchungen an einigen Heteroliganden-Hydroxo-Komplexen von Lanthanid-Ionen mit Iminodiessigsäure und Citracon- oder Maleinsäure
Zusammenfassung Es wurden ternäre Komplexe von La(III), Pr(III), Nd(III), Gd(III) und Dy(III) mit gemischten Liganden [Iminodiessigsäure (IMDA) und Citraconsäure (CCA) oder Maleinsäure (MIA)] mittelspH-metrischer Methoden untersucht. Diese Komplexe werden über die stufenweise Addition des Sekundärliganden (IMDA) zu den primär gebildeten 1:1 Ln(III)—CCA/MIA Spezies gebildet. Zugleich erleiden die resultierenden ternären Komplexe Hydrolyse und gehen in die entsprechenden Hydroxo-Komplexe über. Die Stabilitätskonstanten der Hydroxo-Komplexe wurden für konstante Temperatur (27 ± 1°C) und Ionenstärke (I=0.1M KNO3) berechnet. Die relative Reihung bezüglich der Stabilitäten ergab sich folgendermaßen: La(III)相似文献