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1.
A. D. Chervonnyi N. A. Chervonnaya 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(12):1914-1925
The enthalpies of sublimation Δsub H 0(298) of 4f metal trichlorides were calculated by the second and third laws of thermodynamics from saturated vapor pressures using the thermodynamic functions of the condensed and gaseous states suggested by us. The set of the Δsub H o(298) enthalpies was analyzed to determine the most reliable values. The enthalpies of atomization found from these values were compared with those calculated from the measured equilibrium constants of gas phase reactions with the participation of the compounds under consideration and the enthalpies of atomization found from the experimental appearance potentials AP(Ln+/LnCl3). Recommended Δat H o(298) values were obtained for all the 4f metal trichlorides. 相似文献
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3.
I. E. Paukov Yulia A. Kovalevskaya Elena V. Boldyreva 《Journal of Thermal Analysis and Calorimetry》2008,93(2):423-428
Heat capacity C
p(T) of the orthorhombic polymorph of L-cysteine was measured in the temperature range 6–300 K by adiabatic calorimetry; thermodynamic functions were calculated
based on these measurements. At 298.15 K the values of heat capacity, C
p; entropy, S
m0(T)-S
m0(0); difference in the enthalpy, H
m0(T)-H
m0(0), are equal, respectively, to 144.6±0.3 J K−1 mol−1, 169.0±0.4 J K−1 mol−1 and 24960±50 J mol−1. An anomaly of heat capacity near 70 K was registered as a small, 3–5% height, diffuse ‘jump’ accompanied by the substantial
increase in the thermal relaxation time. The shape of the anomaly is sensitive to thermal pre-history of the sample. 相似文献
4.
T. F. Ibragimov M. G. Levkovich V. A. Saprykina Kh. M. Shakhidoyatov 《Chemistry of Natural Compounds》2010,46(5):767-770
N-Chloroacetylcytisine was synthesized by acylation of (–)-cytisine. Stable Z- and E-conformers with respect to rotational isomerism around the N-12–CO bond were found in PMR spectra at room temperature. The
point at which PMR resonances of the Z- and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated. 相似文献
5.
A. M. Makarevich B. G. Kimel’ N. P. Kuz’mina 《Russian Journal of Inorganic Chemistry》2007,52(11):1775-1780
The composition of aqueous solutions of the heterometallic chelates MLnDTPA and Ln2M3(EDTA)3 (H5DTPA = diethylenetriaminepentaacetic acid; H4EDTA = ethylenediaminetetraacetic acid; Ln = Eu, La; M = Ni, Mn) and the monometallic chelates H3Ni(DTPA), HNi2(DTPA), H2La(DTPA), and H2Eu(DTPA) was studied by electrospray mass spectrometry (ESIMS). The mass spectra indicate that there is equilibrium between chelated rare-earth and 3d-metal ions in the aqueous solution of the heterometallic chelates. Both monometallic and bimetallic diethylenetriaminepentaacetates are observed for the 3d elements. The intensity ratio of the chelated rare-earth and 3d-metal ions in the aqueous solutions of the heterometallic complexes is in agreement with the ratio of the stability constants of the respective monometallic chelates. 相似文献
6.
A. V. Lezov G. E. Polushina A. A. Lezov P. S. Vlasov N. S. Domnina 《Polymer Science Series A》2011,53(2):93-101
The hydrodynamic and conformational properties of molecules of poly(N,N-diallyl-N,N-dimethylammonium chloride) and N,N-diallyl-N,N-dimethylammonium chloride-maleic acid copolymers of different compositions in solutions with various ionic-strength and pH
values, as well as of the polyelectrolyte complex based on the copolymer with dodecyl sulfate anions in chloroform, are studied.
For poly(N,N-diallyl-N,N-dimethylammonium chloride) molecules in a 1 M NaCl solution, the Kuhn segment length and the hydrodynamic diameter of the
chain are estimated as A = 3.9 nm and d = 0.48 nm, respectively. In acidic solutions with pH 3.5, the copolymers demonstrate behavior typical for polyelectrolytes.
In an alkaline solution with pH 13, when 1 M NaCl is added to the solution of the copolymer containing 29 mol % maleic acid
units, there is an antipolyelectrolyte effect that manifests itself as an increase in the intrinsic viscosity of the copolymer
and in the hydrodynamic radius of its molecules. It is found that an increase in the fraction of maleic acid units in the
copolymer from 12 to 42 mol % brings about a reduction in the equilibrium rigidity of its macromolecules from 4.1 to 2.2 nm.
The equilibrium rigidity of polyelectrolyte-complex molecules is higher than that of initial copolymer molecules owing to
steric interactions arising between the aliphatic chains of dodecyl sulfate anions. In an electric field, the molecules of
the complex are oriented owing to the induced dipole moment resulting from the displacement of dodecyl sulfate anions along
the chain contour. 相似文献
7.
In neutral zinc the 4p
2 configuration lies above the 3d
104s ionization limit and its levels become perturbers in the continuum. Lines have been identified in the Zn I spectrum for the
multiplet, whereas no lines have been found for transitions to 4p
2 1
D or 1
S. In this paper, cross sections for photoionization from 4s4p levels are reported that reveal the positions and widths of the 4p
2 resonances. Calculations were performed using the multiconfiguration Hartree-Fock (MCHF) and B-spline R-matrix (BSR) method. Results from Breit–Pauli calculations that ignore the background continua are also presented. Included
in the latter are energies for the levels and transition data (transition energies, line strengths, f-values, and A-rates) for all E1 transitions between these
levels. Transition energies and the agreement in the length and velocity values, particularly for allowed transitions, indicate
the accuracy of the computational model. Line widths are compared with other estimates.
Contribution to the Serafin Fraga Memorial Issue. 相似文献
8.
N. N. Makhmudiyarova G. M. Kiyamutdinova A. G. Ibragimov U. M. Dzhemilev 《Russian Journal of Organic Chemistry》2017,53(4):604-609
An efficient method has been developed for the synthesis of 7,16,25-triaryl-7,8,16,17,25,26-hexahydro-6H,15H,24H-tribenzo[f,m,t][1,5,8,12,15,19,3,10,17]hexaoxatriazacyclohenicosines, 3,8-diaryl-2,3,4,7,8,9-hexahydrobenzo[1,2-e:4,3-e′]bis[1,3]oxazines, 3,9-bis(chlorophenyl)-3,4,9,10-tetrahydro-2H,8H-benzo[1,2-e:3,4-e′]bis[1,3]oxazines, and 2,9-bis(chlorophenyl)-1,2,3,8,9,10-hexahydrobenzo[1,2-e:6,5-e′]bis-[1,3]oxazines via cycloaminomethylation of pyrocatechol, resorcinol, and hydroquinone with N,N-bis(methoxymethyl) anilines in the presence of samarium catalysts. 相似文献
9.
Marco Bortoluzzi Dario Battistel Gabriele Albertin Salvatore Daniele Francesco Enrichi Riccardo Rumonato 《Chemical Papers》2016,70(1):43-52
1,10-Phenanthroline-5,6-dione (Phd) complexes of group 3 and lanthanide elements having formulae Ln(hfac)3(Phd) (Ln = Y, Eu, Yb; hfac = hexafluoroacetylacetonate) were synthesised and characterised. Complexes of d-block elements of the type [MCl(Phd)(p-cymene)]+ (M = Ru, Os) were also prepared. In all these species, coordination of the polydentate ligand occurs by the N-donor moieties, as indicated by DFT calculations. The novel compounds were tested, together with fac-ReBr(Phd)(CO)3, as precursors for the preparation of heterobimetallic d/f derivatives. The reaction of the rhenium complex with yttrium or lanthanide anhydrous triflate salts led to the formation of the complexes ReBr(CO)3(N,N′-Phd-O,O′)Ln(OTf)3(THF) (Ln = Y, Eu, Yb), where the trivalent ions interacted with the quinonoid moiety. The redox properties of the rhenium centre were strongly affected by the coordination of Ln(OTf)3, as observed by comparing the cyclic voltammetry measurements carried out on fac-ReBr(Phd)(CO)3 and on ReBr(CO)3(N,N′-Phd-O,O′)Y(OTf)3. 相似文献
10.
I. G. Davydenko Yu. L. Slominskii O. I. Kalchenko A. V. Gutov A. N. Chernega A. I. Tolmachev 《Russian Chemical Bulletin》2008,57(1):159-164
A procedure was developed for the synthesis of derivatives of the new heterocyclic system, benzo[cd]furo[2,3-f]indole, based on the cyclodehydration of 6-acylmethyloxy-1-alkyl-benzo[cd]indol-2(1H)-ones. Either 7- or 8-aryl derivatives of benzo[cd]furo[2,3-f]indol-4(5H)-ones can be prepared depending on the reaction conditions. The molecular and crystal structures of 7- and 8-phenylbenzo[cd]furo[2,3-f]indol-4(5H)-ones were established by X-ray diffraction. 相似文献
11.
O. G. Strukov V. B. Kondrat’ev Z. V. Vlasova V. A. Petrunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(1):100-105
Conformers of the biologically active compounds CH3P(O)(OR)(SCH2CH2NR 2 ′ ), where (I) R = i-C4H9, R′ = C2H5 and (II) R = C2H5, R′ = i-C3H7, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object. 相似文献
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13.
Ju-Lan Zeng Sai-Bo Yu Bo Tong Li-Xian Sun Zhi-Cheng Tan Zhong Cao Dao-Wu Yang Jing-Nan Zhang 《Journal of Thermal Analysis and Calorimetry》2011,103(3):1087-1093
An N-tert-butyloxycarbonylated organic synthesis intermediate, (S)-tert-butyl 1-phenylethylcarbamate, was prepared and investigated by means of differential scanning calorimetry (DSC) and thermogravimetry
(TG). The molar heat capacities of (S)-tert-butyl 1-phenylethylcarbamate were precisely determined by means of adiabatic calorimetry over the temperature range of 80-380 K.
There was a solid–liquid phase transition exhibited during the heating process with the melting point of 359.53 K. The molar
enthalpy and entropy of this transition were determined to be 29.73 kJ mol−1 and 82.68 J K−1 mol−1 based on the experimental C
p–T curve, respectively. The thermodynamic functions, [HT0 - H298.150 H_{T}^{0} - H_{298.15}^{0} ] and [ST0 - S298.150 S_{T}^{0} - S_{298.15}^{0} ], were calculated from the heat capacity data in the temperature range of 80–380 K with an interval of 5 K. TG experiment
showed that the pyrolysis of the compound was started at the temperature of 385 K and terminated at 510 K within one step. 相似文献
14.
A. I. Vorob’eva M. S. Babaev L. V. Spirikhin N. M. Shishlov S. V. Kolesov 《Russian Journal of Applied Chemistry》2016,89(1):160-164
A copolymer of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid of constant composition was prepared under the conditions of radical initiation. The possibility of the functionalization of the copolymer with drugs containing amino groups by polymer-analogous transformations was examined. Conditions were found for preparing conjugates of the copolymer with isoniazid. The structures and the quantitative compositions of the conjugates were determined by 13С NMR spectroscopy, and the possibility of preparing conjugates with controlled drug content was demonstrated. 相似文献
15.
R. N. Shakhmaev A. Sh. Sunagatullina D. A. Akimova V. V. Zorin 《Russian Journal of Organic Chemistry》2017,53(4):615-617
An efficient synthetic approach to 2E,4E and 2E,4Z isomers of ethyl 5-chloropenta-2,4-dienoate has been developed on the basis of one-pot oxidation–olefination of readily accessible (E)- and (Z)-3-chloroprop-2-en-1-ols by the action of barium manganate and ethyl (triphenyl-λ5-phosphanylidene)acetate. 相似文献
16.
Eberhard Reimann Rainer Hertel Jürgen Krauss 《Monatshefte für Chemie / Chemical Monthly》2008,139(6):673-684
Alkylation of Reissert compounds derived from 3-methylisoquinolines with several 2-cyanobenzylbromides followed by hydrolytic cleavage provided the corresponding 1-benzyl-3-methylisoquinolines. Treatment of the latter with methylmagnesiumiodide caused cyclization to the title compounds rather than formation of 2-acetylbenzylisoquinolines. 相似文献
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18.
Background
Adenylation of nicotinate mononucleotide to nicotinate adenine dinucleotide is the penultimate step in NAD+ synthesis. In Escherichia coli, the enzyme nicotinate mononucleotide adenylyltransferase is encoded by the nadD gene. We have earlier made an initial characterization in vivo of two mutant enzymes, NadD72 and NadD74. Strains with either mutation have decreased intracellular levels of NAD+, especially for one of the alleles, nadD72. 相似文献19.
N. A. Ivanova Z. R. Valiullina O. V. Shitikova L. V. Spirikhin M. S. Miftakhov 《Russian Journal of Organic Chemistry》2008,44(3):335-339
(2S,3S,4S)-2,3-O-Isopropylidene-4-(methoxycarbonylmethyl)cyclopentan-1-one was synthesized starting from D-ribose through methyl (Z)-3-(5-acetyl-2,2-acetoxyacetyl-2,2-dimethyl-1,3-dioxolan-4-yl)prop-2-enoate which was subjected to cyclization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, followed by decarboxylation. 相似文献
20.
Previously unknown E isomers of azomethines (Schiff bases) were synthesized from vanillal and vanillin esters by their reaction with cyclohexylamine. 相似文献