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371.
An Efficient and Convenient Synthesis of 2-Thio[1,2,4]triazolo[1,5-c]quinazoline and its Derivatives
Alexandr V. Karpenko Sergey I. Kovalenko Svetlana V. Shishkina Oleg V. Shishkin 《Monatshefte für Chemie / Chemical Monthly》2006,137(12):1543-1549
Summary. 4-Hydrazinoquinazoline with carbon disulfide underwent a recyclization reaction. The title compound 2-thio[1,2,4]triazolo[1,5-c]quinazoline was obtained after treatment of 4-hydrazinoquinazoline with potassium ethylxanthogenate via a facile in situ Dimroth-like rearrangement of the expected [4,3-c] system. Its structure was established by X-ray diffraction study and confirmed by an independent synthesis, starting from
o-aminobenzonitrile. 相似文献
372.
Vladimír Havlí
ek Alexandr Jegorov Petr Sedmera Miroslav Ryska 《Journal of mass spectrometry : JMS》1993,28(12):1440-1447
The mass spectrometric sequence determination of amino acid residues in cyclosporins using fast atom bombardment, collisionally activated dissociations in the first field-free region and linked B/E scan is described. The general fragmentation scheme was derived from the spectra of cyclosporins A, B, C, D, F, G, L and [DH-MeBmt1]CS. The main fragmentation pathways start by primary splitting between amino acids 2–3, 1–11 and 5–6. The corresponding N-terminal b-type ions are common fragment types in the mass spectra. The 1–11 splitting can be enhanced by the introduction of a lactone group into the peptide ring by conversion of cyclosporins into isocyclosporins. The fragmentation scheme was used for amino acid sequence determination in four new natural cyclosporins, [MeLeu1]CS, [Leu4]CS, [Ile4]CS and [Leu5]CS. 相似文献
373.
Zdzislaw Narankiewicz Alexandr L. Blumenfeld Veronica L. Bondareva Irina A. Mamedyarova Marina N. Nefedova Viatcheslav I. Sokolov 《Journal of inclusion phenomena and macrocyclic chemistry》1991,11(3):233-245
Spin-lattice relaxation time measurements in laboratory and rotating frames as well as proton second moment analysis have been used to investigate molecular motions in -cyclodextrin (CD) and its solid inclusion complexes with the title organometallic compounds. Different dynamical processes have been identified in the host lattice along with high mobility of the ferrocene and ruthenocene guest molecules. The Arrhenius parameters of all motions were obtained. The assumption based on the second moment measurements was made about the axial structure of the ferrocene complex and the equatorial one of the ruthenocene complex at low temperatures. The bridged ferrocenophane molecule was shown to be rigid on the NMR time scale. The ternary inclusion complex of -CD with ruthenocene and iodine was also studied and no evidence of redox reactions was observed. 相似文献
374.
Vladimir N. Afanasiev Alexandr N. Ustinov Irina Yu. Vashurina 《Journal of solution chemistry》2006,35(11):1477-1491
The isentropic compressibilities of aqueous solutions of potassium iodide, from dilute to almost saturated, were determined at 288 to 308 K based on precise measurements of the speed of ultrasound. Using proper correlations, the hydration numbers (h) were calculated as well as the molar volume and compressibility parameters of the hydrated complexes (V
h
, β
h
V
h
) of water in the hydration shell (V
1h
, β1h
V
1h), and of the cavity containing stochiometric mixtures of K+ and I−
ions (V
2h, β2h
V
2h). It is revealed that under the studied conditions, the obtained values of h and β
h
V
h are independent of temperature whereas the molar compressibility of the hydration shell β
h
V
h) is independent of concentration. The electrostatic field of the ions is shown to influence the temperature dependence of the molar volume of water in the hydration shell more substantially than a change of pressure alone influences the temperature dependence of the molar volume of pure water. 相似文献
375.
A new modification of the adiabatic compressibility method of investigating solvation in solutions is presented and applied
to the analysis of the following structurally-related characteristics of hydrated complexes of seawater electrolytes (NaCl,
KCl, MgCl2, CaCl2, Na2SO4, MgSO4) at different concentrations (0.1 to 5.0 mol⋅kg−1) and temperatures (278.15 to 308.15 K): solvation numbers (h) and their dependences on concentration, volumes of stoichiometric mixtures of ions without their hydration shells (V
2h
), compressibilities (β
1h
) and molar volumes of water in their solvation shells (V
1h
), their dependences on concentration and temperature, etc. 相似文献
376.
Alexandr L. Antipov Alexey Yu. Bykovsky Anton A. Egorov 《Journal of Russian Laser Research》2008,29(4):322-335
A multiple-valued-logic protected-data coding method is proposed for distant ordering/disordering of a fuzzy logic model accumulated
in a robotic agent. Fuzzy-rule-set disordering is a means to realize the distributed logic lock, preventing a hacker from
unapproved use of the robotic device itself or its internal data. The multiple-valued-logic protected-data coding is the method
used here to increase greatly the secret-key space. Optical-data line is to be used for distant transfer of secret codes between
the key and lock devices.
Talk presented at the oral issue of J. Russ. Laser Res. dedicated to the memory of Professor Vladimir A. Isakov, Professor
Alexander S. Shumovsky, and Professor Andrei V. Vinogradov held in Moscow February 21–22, 2008. 相似文献
377.
Tomáš Holas Pavel Berka Michaela Mádlová Jana Klimentová Alexandr Hrabálek 《Thermochimica Acta》2006,441(2):116-123
A series of alkylammonium-alkylcarbamates with different chain length including transdermal permeation enhancer Transkarbam 12 have been prepared and characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), temperature-dependent Fourier transform infrared spectroscopy (FTIR) and temperature-dependent X-ray powder diffraction. Four transitions have been observed including solid-solid transition (I), melting (II), decomposition of the carbamate salt (III) and boiling of the released amine (IV). The first transition was connected with rearrangement of the hydrocarbon chain packing and unusual shift of symmetric CH2 stretching vibration in the IR spectra to lower wavenumbers indicated increase of conformational order. The second transition represented melting of the molecule and the third one was attributed to the decomposition of the carbamate salt into two amine molecules and carbon dioxide as evidenced by combination of DSC and TGA curves. 相似文献
378.
Pavel A. Abramov Maxim N. Sokolov Alexandr V. Virovets Eugenia V. Peresypkina Cristian Vicent Vladimir P. Fedin 《Journal of Cluster Science》2009,20(1):83-92
Reaction of [Mo6(μ3-Cl)8Cl6]2− with H2Se, generated in situ from ZnSe and 4 M HCl under hydrothermal conditions lead to the substitution of one or two bridging
chlorides, depending on the reagents ratio. With the Mo6/ZnSe 1:3 molar ratio [Mo6(μ3-SeCl7)Cl6]3− forms selectively in high yield. Further substitution is more hindered, and even at 1:20 cluster-to-selenide molar ratio
a mixture of [Mo6(μ3-SeCl7)Cl6]3− and [Mo6(μ3-Se2Cl6)Cl6]4− is formed. The products were characterized by X-ray, Raman spectra and electrospray ionization mass spectrometry. 相似文献
379.
Alexandra E. Raevskaya Alexandr L. Stroyuk Stepan Ya. Kuchmiy Volodymyr M. Dzhagan Dietrich R.T. Zahn Steffen Schulze 《Solid State Communications》2008,145(5-6):288-292
Selenium nanoparticles were obtained by a new facile synthetic route from gelatin-stabilized aqueous colloidal solutions. The dependence of structural and optical properties of the nanoparticles upon duration of post-synthesis thermal treatment of Se sols was studied by optical absorption, photoluminescence and Raman scattering. We have shown that ageing of colloidal Se solutions at elevated temperatures results in an enlargement and crystallization of selenium nanoparticles, accompanied with noticeable changes in their optical spectra: an enhancement of the photoluminescence of the NPs, incorporated in gelatin films; a “red” shift of both the absorption threshold and emission band maximum; appearance of new peaks in Raman spectra, attributed to the formation of the crystalline phase in the course of the ageing. 相似文献
380.