共查询到20条相似文献,搜索用时 15 毫秒
1.
Khatymov R. V. Muftakhov M. V. Mazunov V. A. Nedopekin D. V. Galyautdinov I. V. Odinokov V. N. 《Russian Chemical Bulletin》2002,51(2):306-310
Specificity of the dissociative attachment of low-energy electrons to ecdysteroid molecules (viz., 20-hydroxyecdysone 2,3:20,22-diacetonide, 20-hydroxyecdysone 20,22-acetonide, and poststerone 2-acetate) was found, which is manifested as the formation of long-lived pseudo-molecular negative ions that appeared due to the elimination of the H2 and H2O molecules. These rearrangements are resulted from the formation of the system of conjugated double bonds in the ecdysteroid skeleton, stabilizing the lowest vacant molecular orbital. 相似文献
2.
S. V. Pikhtovnikov V. K. Mavrodiev I. I. Furley R. R. Gataullin I. B. Abdrakhmanov 《High Energy Chemistry》2006,40(4):224-229
Processes of the formation of negative ions from aniline and its derivatives were studied by the resonance electron capture technique. The results were compared with those obtained earlier for molecules of benzene, phenol, and chlorophenols. It was concluded that the processes of formation of negative ions in aniline differ substantially from those in benzene and phenol. The triplet series of resonances beginning from the resonance at 2.6 eV is observed. 相似文献
3.
4.
Russian Chemical Bulletin - The modified dipeptide, Captopril, was studied to determine the effect of lateral functional groups on the decay of biomolecules in resonant reactions of electrons with... 相似文献
5.
R. V. Khatymov M. V. Muftakhov P. V. Schukin V. A. Mazunov 《Russian Chemical Bulletin》2004,53(4):738-741
The processes of resonant dissociative electron attachment to the molecules of dibenzo-p-dioxin and its chlorinated derivatives containing one to four chlorine atoms (totally eight compounds) were investigated. It was established that 2,3,7-trichlorodibenzo-p-dioxin; 1,2,3,4-tetrachlorodibenzo-p-dioxin; 1,3,7,8-tetrachlorodibenzo-p-dioxin, and 2,3,7,8-tetrachlorodibenzo-p-dioxin molecules are chatacterized by positive electron affinities. At electron energies below 2 eV, the electron attachment is caused by the shape resonances. Based on the energy correlation between the negative ion resonance peaks at 3—4 eV and the UV band maxima, it was suggested that electron attachment in this energy region occurs by the mechanism of inter-shell resonance with the molecular singlet-excited states as parents. The possibility for the rearrangement processes resulting in oxy-anionic structures to occur is substantiated. 相似文献
6.
S. V. Pikhtovnikov V. K. Mavrodiev S. P. Ivanov V. P. Krivonogov Yu. P. Murinov I. I. Furlei 《Russian Chemical Bulletin》2005,54(6):1402-1404
The enol forms of uracil and its derivatives were detected in the gas phase by mass spectrometry. The [M - H]− ion is produced by resonance electron capture to the lowest unoccupied molecular orbitals, the process being accompanied
by the detachment of the hydrogen atom from the nitrogen atom of the diketo form (low-energy peak at 0.8 eV) and from the
oxygen atom of the enol form (in the energy region of 1.4 eV). The gas phase contains ∼10−3% of the enol form.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1360–1362, June, 2005. 相似文献
7.
I. I. Furlei E. A. Burmistrov F. Z. Galin V. N. Iskandarova G. A. Tolstikov 《Russian Chemical Bulletin》1987,36(11):2296-2300
Conclusions The fragmentation of substituted cyclopropanes under the conditions of dissociative electron capture is accompanied by the opening of the cyclopropane ring and is determined by the nature of the functional group. The increase in the number of electron-acceptor substituents noticeably stabilizes the molecular negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2473–2478, November, 1987. 相似文献
8.
M. V. Muftakhov P. V. Shchukin R. V. Khatymov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(9):1730-1736
Resonant electron attachment by orotic acid molecules (6-COOH-uracil) are studied in the energy range of 0–14 eV via negative ion mass spectrometry. Molecular ions, whose lifetimes relative to electron autodetachment are found to be ~300 μs are recorded in the region of thermal electron energies; they form in the valence state through a vibration-excited resonance mechanism. Unlike unsubstituted uracil, most dissociative processes occur in the low-energy region of <4 eV and are due to carboxylic anions. An absolute cross section of 2.4 × 10?17 cm2 is found for the most intense fragment ions [M–H]– at an output energy of 1.33 eV. The kinetics of decarboxylation is considered for these ions. This could be a model reaction for the last stage of uridine monophosphate biosynthesis. 相似文献
9.
10.
I. I. Furlei V. M. Yanybin E. G. Galkin V. K. Mavrodiev D. V. Petrov S. S. Lozhkin 《High Energy Chemistry》2009,43(2):129-132
The formation of negative ions from pyrazoline and its derivatives was studied by the negative-ion and resonance-electron-capture mass spectrometry techniques. The results were compared with those of the dissociation processes of the excited-state pyrazoline molecule, and resemblance to the fragmentation processes of the molecular negative ion was revealed. 相似文献
11.
M. V. Muftakhov R. V. Khatymov V. A. Mazunov V. N. Odinokov I. V. Galyautdinov 《Russian Chemical Bulletin》2000,49(4):713-716
The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative
ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by
the elimination of H2O and H2 molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH2O].− (n=1–3) and [M−H2−nH2O].− (n=0−3) ions that are generated exclusively by the rearrangement.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000. 相似文献
12.
Yu. S. Nekrasov V. K. Mavrodiev V. A. Mazunov V. I. Khvostenko N. P. Avakyan I. I. Kritskaya 《Russian Chemical Bulletin》1985,34(6):1308-1310
Conclusions The major pathways were established for the fragmentation of -allyliron tricarbonyl halides upon dissociative electron capture. The mechanisms for the formation of C3H5Fe(CO)
3
–
anions in the gas phase and under electrochemical reduction conditions on a dropping mercury electrode were shown to differ. A predominant effect was proposed for solvation factors on the electrochemical reduction in the condensed phase.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1428–1430. 相似文献
13.
V. I. Khvostenko I. I. Furlei V. K. Mavrodiev G. V. Leplyanin A. R. Derzhinskii 《Russian Chemical Bulletin》1984,33(7):1517-1519
Conclusions The low energy resonance in the negative ion mass spectra of alkyl vinyl, 2,3-epoxypropyl alkyl, and 2, 3-epithiopropyl alkyl sulfies and their sulfoxide and sulfone analogs is related to electron capture in the * orbital of the S-C bond. The oxidation state of the sulfur atom has no qualitative effect on the major processes involved in the formation of the negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, 1653–1657, July, 1984. 相似文献
14.
New resonance states were discovered for the negative molecular ions of thiophene and selenophene and a series of resonances was found for various heterocyclic compounds in the region 3.0–3.6 eV. The low-energy resonances at 1.65–2.3 eV are formed by a resonance mechanism of a form of the molecular ground state, while an electronically excited Feschbach resonance is responsible for the series of resonance states at 3.0–3.6 eV. The mother state for the latter resonance states is the first triplet state of these molecules. The first triplet state of selenophene is at 3.6±0.15 eV.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 925–927, April, 1990. 相似文献
15.
16.
17.
Factors considered in the development of a method for the determination of toxic, water-soluble benzidines. involved providing a good technique for their adequate recovery, converting quantitatively the isolated amines to relatively stable derivatives suitable for measurement and storage, coupled with relative ease of preparation of the derivatives, and resolving the prepared compounds during their measurement. Benzidine and dichlorobenzidine are quantitatively extracted from wastewater and measured quantitatively through the preparation of their respective pentafluoropropionamides (PFP) by using PFP-imidazole. Overall recovery efficiency for benzidines from wastewater ranges from 91 to 103%. These derivatives are relatively stable compounds and have detection limits of 0.2 pg or less, when electron capture detection is used with gas chromatography. Derivatives of o-tolidine and dianisidine are also described. 相似文献
18.
Muftakhov MV Khatymov RV Mazunov VA Ponomarev DA Takhistov VV Vatlina LP 《Rapid communications in mass spectrometry : RCM》2000,14(16):1482-1484
Appearance energies for [M - H](-) ions from phenol (I), 4-chlorophenol (II), pentachlorophenol (III) and pentachlorothiophenol (IV) were measured. The following thermochemical data were deduced from experiment: DeltaH(acid) values of 343.3, 335.7, 317.1 and 317.1 kcal mol(-1) for RH molecules (I, II, III, and IV, respectively) and electron affinities (EAs) of R(.) free radicals 2.55, 2.90, 3.79, and 3.65 eV, respectively. Our data for phenol (I) and 4-chlorophenol (II) demonstrate a higher stabilization of ArO(-) anions than was previously accepted. Using the enthalpic shift procedure for molecules and a series of isodesmic reactions for free radicals, earlier elaborated by the authors, a new Delta$bf H_bf fbf 0$ values for the following gas-phase species were obtained (kcal mol(-1)): C(6)Cl(5)Br (5.0), C(6)Cl(5)SH (8.5), p-ClC(6)H(4)C(.) (2. 0), C(6)Cl(5)C(.) (-15), C(6)Cl(5)S(.) (44). Copyright 2000 John Wiley & Sons, Ltd. 相似文献
19.
Reactions of quinazoline 1 with indole, pyrogallol and 1-phenyl-3-methylpyrazol-5-one in the presence of acid led to C-4 adducts 2, 3 and 5. Adduct 4 is formed by heating 1 with 1,3-dimethylbarbituric acid without acid catalysis. 1-Phenyl-3-methylpyrazol-5-one reacts with 1 without acid catalysis to form dipyrazolylmethane 6. 4-Chloroquinazoline 8 reacts with 1-phenyl-3-methylpyrazol-5-one to form 4-(1-phenyl-3-methyl-5-oxopyrazol-4-yl) quinazoline 9 and dipyrazolylmethane 6. Heating 8 with 2-methylindole leads to the formation of 4-(2-methylindol-3-yl) quinazoline 10 and tris(2-methylindol-3-yl)methane 11. 相似文献
20.
A. S. Vorob'ev I. I. Furlei A. Sh. Sultanov V. I. Khvostenko G. V. Leplyanin A. R. Derzhinskii G. A. Tolstikov 《Russian Chemical Bulletin》1989,38(7):1388-1394
1. | The formation of resonance states of negative molecular ions by interaction of an electron with the molecules of ethylene oxide, ethylene sulfide, and their derivatives in the high-energy region takes place through a mechanism of electronically excited Feschbach resonance with excitation of an electron from several occupied molecular orbitals to one and the same unoccupied molecular orbital, which coincides with the unoccupied molecular orbital of the first singlet transition of the molecule. An additional electron is captured in a fully symmetric Rydberg orbital that is formed in the field of the excited molecule. |
2. | The dissociation of the negative molecular ions proceeds in accordance with the principle of orbital correlation, and the symmetry of their electronic state is determined by the symmetry of the occupied molecular orbital (from which the electron is excited) and the symmetry of the unoccupied molecular orbital (into which the electron passes). |
3. | In the molecules of 2,3-epoxypropyl ethyl sulfide, glycidol, and epichlorohydrin, the unshared electron pairs of the oxygen atom of the three-membered heterocycle and the sulfur atom of the substituent (or the oxygen or chlorine atom of the substituent) do not interact with each other to any appreciable degree. |