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1.
T. M. Prokop’eva V. A. Mikhailov M. K. Turovskaya E. A. Karpichev N. I. Burakov V. A. Savelova I. V. Kapitanov A. F. Popov 《Russian Journal of Organic Chemistry》2008,44(5):637-646
Bis(dialkylamide)hydrogen dibromobromates were synthesized and their reactivity was investigated in decomposition of diethylphosphonic, diethylphosphoric, and 4-toluenesulfonic acids 4-nitrophenyl esters. The nucleophilic reactivity of a typical α-nucleophile, hypobromite ion, is independent of the source of the active bromine. The cetyltrimethylammonium dibromobromate is a unique reagent for destruction of ecotoxicants. In weakly alkaline media the half-life of 4-nitrophenyl diethylphosphonate did not exceed 6 s at [BrO?] 0.02 mol l?1, and the apparent reaction rate compared to water increased ~40-fold. The main factor governing the micellar effects of surfactants is concentrating the substrate in the micellar pseudophase. 相似文献
2.
T. N. Solomoichenko Yu. S. Sadovskii T. M. Prokop’eva E. A. Karpichev I. V. Kapitanov Zh. P. Piskunova V. A. Savelova A. F. Popov 《Theoretical and Experimental Chemistry》2006,42(6):364-370
We have studied the nucleophilicity of the hydroperoxide anion relative to 4-nitrophenyl diethyl phosphonate (NPDEPS) in the
presence of cetyltrimethylammonium bromide (water, 25 °C) while varying the acidity of the medium and the hydroperoxide anion
concentration over a broad range. The increase in the reaction rate when the reaction is transferred to a micellar pseudophase
is as high as ∼10-fold, which is explained by concentration effects. In CTAB micelles, as in water, the hydroperoxide ion
is one of the most effective α-nucleophiles, and the size of the α-effect, characterized by the ratio of the second-order rate constants for reactions of HOO− and OH− anions with NPDEPS, remains practically constant and reaches a value of ∼50-fold.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 6, pp. 357–363, November–December, 2006. 相似文献
3.
Yu. S. Simanenko E. A. Karpichev T. M. Prokop’eva V. A. Savelov A. F. Popov 《Theoretical and Experimental Chemistry》1998,34(2):76-80
A detailed extrathermodynamic analysis of the behavior of oximate ions (pKa≈7–13) in reactions with various types of substrate was undertaken. For oximate ions with pKa≥9.0, irrespective of the nature of the acyl group, the reactivity of the oximes tends toward that of the alcoholate ions,
and their α-effect disappears. The reason for this is the unfavorable solvation effects of the solvent.
Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul.,
Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 86–90, March–April,
1998. 相似文献
4.
Simanenko Yu. S. Popov A. F. Karpichev E. A. Prokop'eva T. M. Savelova V. A. Bunton C. A. 《Russian Journal of Organic Chemistry》2002,38(9):1314-1325
1-Cetyl-3-(2-hydroxyiminopropyl)imidazolium chloride and bromide were synthesized for the first time. These compounds are functionalized zwitterionic surfactants which give rise to micelle formation in aqueous solution. Kinetic and thermodynamic analysis of nucleophilic cleavage of p-nitrophenyl p-toluenesulfonate, diethyl p-nitrophenyl phosphate, and ethyl p-nitrophenyl ethylphosphonate in the presence of 1-cetyl-3-(2-hydroxyiminopropyl)imidazolium halide micelles showed that the latter are powerful nucleophilic reagents whose kinetic behavior can be described in terms of a simple pseudophase distribution model. The efficiency of substrate solubilization with zwitterionic surfactant micelles and the reactivity of the oximate fragment in the micelle phase were estimated on a quantitative level. The observed acceleration of SN2 reactions with the examined p-nitrophenyl esters relative to analogous reactions of zwitterionic 1-methyl-3-(2-hydroxyiminopropyl)imidazolium halides is, respectively, 12800, 550, and 900 times; it is explained mainly by increased concentration of the reactants in micelles. 相似文献
5.
Yevgen Posokhov Alexander Gorski Jens Spanget-Larsen Fritz Duus Poul Erik Hansen Jacek Waluk 《Chemphyschem》2004,5(4):495-502
Thioacetylacetone and its variously deuterated isotopomers have been investigated using electronic and vibrational spectroscopy combined with quantum chemical calculations. Thioacetylacetone is known for its photochromic properties, but the structures of the initial and final forms have been the subject of a long debate. Analysis of the IR spectra recorded in low-temperature argon and xenon matrices, room-temperature solutions, and in the gas phase has allowed us to establish the nature of the photochromic species and of its precursor. Similar to the case of another beta-thioxoketone, monothiodibenzoylmethane, the photo-product has been assigned to the nonchelated SH exo-rotamer of the (Z)-enethiol tautomeric form, whereas the dominant ground-state species corresponds to the chelated (Z)-enol tautomeric form. Detailed vibrational assignments have been proposed for both forms based on quantum chemical calculations and polarization experiments. In the case of the chelated (Z)-enol species prevailing in the ground state, a second-order perturbative anharmonic analysis at the B3LYP/cc-pVTZ level indicated strong anharmonic effects associated with the intramolecular hydrogen bond, leading to a shift of more than 600 cm-1 of the wavenumber of the OH-stretching vibration. A small fraction of the SH endo-rotameric chelated (Z)-enethiol form was also detected under unperturbed conditions. The (Z)-enethiol form can be converted into the (Z)-enol form by irradiation at 290 nm. 相似文献
6.
Experimental and Theoretical Investigation of the First‐Order Hyperpolarizability of Octupolar Merocyanine Dyes 下载免费PDF全文
Dr. Frédéric Castet Dr. Mireille Blanchard‐Desce Frédéric Adamietz Yevgen M. Poronik Prof. Dr. Daniel T. Gryko Prof. Dr. Vincent Rodriguez 《Chemphyschem》2014,15(12):2575-2581
Hyper‐Rayleigh scattering experiments and quantum chemical calculations are combined to investigate the second‐order nonlinear optical responses of a series of three‐arm merocyanine derivatives. They exhibit an octupolar hyperpolarizability response with lower amplitude than crystal violet due to a lower extent of the photoinduced charge transfer and reduced bond length alternation. Strong effects on the second‐order optical response measured close to the two‐photon absorption level are clearly evidenced; for example, the effective measured polarization ratio deviates below the ideal octupolar value of 3/2 even at very low excitation power. These effects are attributed to two‐photon absorption resonance, which we believe modifies dynamically the population of the ground state versus that of the excited state. 相似文献
7.
The theory of amplification and lasing without population inversion in a three-level medium with inhomogeneous broadening via the formation of an open V configuration is elaborated. The conditions for energy transfer from the infrared into the visible spectral range, i.e., the conditions of up-conversion n b >n c >n a , and the external field required for saturation of the b?a transition are established. Two-photon resonant Raman transitions in ensemble of mobile atoms of a gas-discharge plasma are analyzed. The frequency shift of the probe field spectrum as a whole is shown to be governed by the frequency shift of the pump field multiplied by the ratio of the wave numbers of the probe amplification field and the pump field. The interaction of atoms through Ne transitions with the pump field (λ=1.15 εm, 2p 4-2s 2 transition) and the lasing field (λ=0.6328 εm, 3s 2-2p 2 transition) with an increase in the lasing frequency by a factor of 1.82 with respect to the absorbed radiation is calculated. 相似文献
8.
Popov A. F. Simanenko Yu. S. Karpichev E. A. Matveev A. A. Matvienko V. N. Prokop'eva T. M. 《Theoretical and Experimental Chemistry》2001,37(6):343-349
An anomalously large increase was found in the rate of cleavage of 4-nitrophenyl 4-toluenesulfonate (13000 times) and diethylphosphate (550 times) by the zwitterionic micelles of 1-cetyl-3-(2-hydroxyiminopropyl)imidazolium chloride and bromide. Detailed kinetic and thermodynamic analysis of these processes made it possible to establish that the main factor responsible for the high rates of reaction in the micellar phase is the concentration of the reagents. 相似文献
9.
Bhanushree Gupta Rahul Sharma Namrata Singh Yevgen Karpichev Manmohan L. Satnami Kallol K. Ghosh 《Journal of Physical Organic Chemistry》2013,26(8):632-642
Kinetic studies of the reactions of tertiary oximes (monoisonitroso acetone; MINA and butane 2,3 dione monooxime; BDMO) with some carboxylate (p‐nitrophenyl acetate and p‐nitrophenyl benzoate), phosphate (p‐nitrophenyl diphenyl phosphate and bis (2,4‐dinitrophenyl) phosphate) and sulfonate (p‐nitrophenyl p‐toluene sulphonate) esters in gemini surfactants have been conducted. The observed first‐order rate constant versus surfactant profiles show micelle‐assisted bimolecular reactions involving interfacial ion exchange between bulk aqueous media and micellar pseudophase. Experimental results showed that MINA exhibited better nucleophilic activity towards ester cleavage than BDMO. Pseudophase model has been applied in order to determine micellar second‐order rate constants and binding constants. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
10.
Substituting CF2 for O4′ in Components of Nucleic Acids: Towards Systems with Reduced Propensity to Form Abasic Lesions 下载免费PDF全文
Dr. Yevgen P. Yurenko Dr. Jan Novotný Prof. Dr. Vladimir Sklenář Prof. Dr. Radek Marek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(49):17933-17943
Intrinsic structural features and energetics of nucleotides containing variously fluorinated sugars as potential building blocks of DNA duplexes and quadruplexes are explored systematically using the modern methods of density functional theory (DFT) and quantum chemical topology (QCT). Our results suggest that fluorination at the 2′‐β or 2′‐α,β positions somewhat stabilizes in vacuo the AI relative to the BI conformations. In contrast, substitution of the CF2 group for the O4′ atom (O4′‐CF2 modification) leads to a preference of the BI relative to AI DNA‐like conformers. All the studied modifications result in a noticeable increase in the stability of the glycosidic bond [estimated by the relaxed force constants (RFC) approach], with particularly encouraging results for the O4′‐CF2 derivative. Consequently, the O4′‐CF2 modified systems are suggested and explored as promising scaffolds for the development of duplex and quadruplex structures with reduced propensity to form abasic lesions and to undergo DNA damage. 相似文献