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1.
Summary The correlation between the RM-values measured in both adsorption and partition chromatography have been investigated for a number of substances such as
heterocyclic bases, naphthols, naphthylamines, and isomeric nitroanilines. Aluminium oxide G, silica gel G, and magnesium
silicate were used as the adsorbent and formamide, ethylene glycol, and a pH=2.4 buffer as the liquid stationary phase. Eleven
solvents served as the mobile phase. It was found that for all compounds investigated the function
is represented by a linear relationship corresponding to the equation
. The constants a and b are characteristic for a compound in a given system of stationary phases (adsorbent and partitioning
liquid).
The values of constant a in a given system for a group of compounds are close to each other and the differences are due to
differences in the structure of the molecules. Changes in the values of b when changing the adsorbent or the partitioning
liquid can be used under certain conditions to characterize the molecular interaction between the sample and the stationary
phases.
It follows from these investigations that the linear correlation between the RM-values measured in liquid adsorption and partition chromatography provides new possibilities in analysis as well as in physicochemical
investigations. 相似文献
2.
Zusammenfassung Es wird die Frage untersucht, ob bei der thermischen Umlagerung von entsprechend allyl-substituierten o-Benzochinol-acetaten der Allyl- oder der Acetoxylrest rascher wandert. Das 2-Allyl-2-acetoxy-cyclohexadienon liefert bei der genannten Reaktion (es sind schon Temperaturen um 100° ausreichend) überwiegend ein Monoacetat des 4-Allylbrenzcatechins. Damit ist bewiesen, daß der Rest
rascher als der Rest
in die p-Stellung zur Carbonylgruppe des Chinolacetates wandert. Eine Wanderung des Acetoxylrestes in die o- oder in die p-Stellung zur Carbonylgruppe, welche zur Bildung von 3-Allyl-brenzcatechin bzw. 2-Allylhydrochinon führen müßte, konnte nicht beobachtet werden. Entsprechend liefert das 2,6-Diallyl-2-acetoxy-cyclohexadienon bei der thermischen Umlagerung überwiegend ein Monoacetat des 3,5-Diallyl-brenzcatechins. Nach einem anderen Mechanismus verläuft die Umlagerung des 2-Methyl-6-allyl-2-acetoxy-cyclohexadienons. Es entsteht neben wenig 2-Methyl-6-allyl-hydrochinon in der Hauptmenge ein Monoacetat des 3-Methyl-5-allyl-brenzcatechins. Es wird also die Allylgruppe durch den in die o-Stellung wandernden Acetoxylrest verdrängt. Auf diese Reaktion wird näher eingegangen, weil sie in engem Zusammenhang mit der Frage steht, ob ganz allgemein eine Umlagerung von o-Chinolacetaten vom Typ
in die Isomeren
möglich ist.Mit 2 AbbildungenHerrn Prof. Dr.F. Feigl zum 70. Geburtstag in alter Freundschaft!F. W.
E. Zbiral, F. Wessely undE. Lahrmann, (gilt als 1. Mitt. dieser Reihe), Mh. Chem.91, 331 (1960). 相似文献
3.
Summary A calculation was made of the group refraction of fluorosulfonyl attached to the carbon atom of an alkyl group;
. 相似文献
4.
P. K. Mishra V. Chakravortty K. C. Dash N. R. Das S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(2):259-264
Synergism has been observed in the extraction of zirconium(IV) by mixtures of Aliquat 336 or Alamine 336 with a neutral donor TBP from aq. HCl solutions. Although the extractant dependency for Zr(IV) is found to be nearly second power with respect to TBP alone, monosolvate is found to be formed for extraction by its mixture with Aliquat 336 or Almine 336. Quantitative extraction is observed with mixtures at a lower acidity than that with individual extractants. The species formed is tentatively assigned to be Q2ZrCl6. TBP, where
for Aliquat 336 and
for Alamine 336. 相似文献
5.
6.
M. P. Terpugova V. G. Kostrovskii V. G. Mazur I. L. Kotlyarevskii 《Russian Chemical Bulletin》1970,19(11):2470-2472
Conclusions The band in the 1270–1280 cm–3 region, corresponding to the vibrations of the -C -N=bond in the grouping
, can be used to determine the presence of azoxy groups in polyazopolyarenes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2623–2625, November, 1970. 相似文献
7.
K. H. Lieser M. Förster und P. Burba 《Fresenius' Journal of Analytical Chemistry》1977,284(3):199-203
Zusammenfassung Die Darstellung eines Celluloseaustauschers mit Salicylsäure als funktioneller Gruppe wurde variiert, um die optimalen Bedingungen sowohl hinsichtlich eines raschen Austausches als auch im Hinblick auf eine hohe Kapazität zu finden. Zwei Arten von Cellulose (vernetzt und mikrokristallin) und verschiedene Reaktionszeiten wurden verwendet. Die Eigenschaften der Reaktionsprodukte wurden mit Hilfe von Titrationskurven zur Bestimmung der Kapazität und durch Messung des nicht-isotopen Austauschs
und des Isotopenaustausches
als Funktion der Zeit untersucht. Optimale Bedingungen wurden mit mikrokristalliner Cellulose und einer Reaktionszeit von 15 min erhalten.
Effect of the conditions of preparation on the properties of a cellulose exchanger containing salicylic acid as a functional group
The preparation of a cellulose derivative containing salicylic acid as functional group was varied in order to find optimal conditions with respect to fast exchange as well as high capacity. Two kinds of cellulose (cross-linked and microcrystalline) and different reaction times were used. The properties of the products were investigated by titration curves to determine the capacity and by measuring the non-isotopic exchange and the isotopic exchange as a function of time. Microcrystalline cellulose and a reaction time of 15 min gave optimal results.相似文献
8.
The Cotton—Mouton effect was used for the study of benzoate, phthalate. isophthalate, and terephthalate anions. The additive tensor characteristics of optical polarizability and magnetic susceptibility ellipsoids have been calculated for C(Ar)-COO– and
. The spatial structures of mono- and deprotonated phthalate anions have been discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 874–876, May, 1993. 相似文献
9.
The difference between the partial molal entropies of ferrocene and ferricinium
has been determined in nine solvents from the temperature dependence of the formal potential of the ferricinium-ferrocene redox couple using a nonisothermal electrochemical cell arrangement in order to probe possible structural reasons for the limitations of the ferrocene assumption for estimating the transfer thermodynamics of single ions between different solvents. In contrast to the uniformly small positive values of
predicted by the Born model, the experimental quantities varied widely from small or even negative values in hydrogen-bonded solvents (–5 to 3 e.u.) to substantially larger values (11–14 e.u.) in dipolar aprotic media. These variations appear to arise chiefly from additional solvent ordering in the vicinity of the ferricinium cation compared to the ferrocene molecule which is enhanced in the aprotic solvents. The variations in
between water and a number of nonaqueous solvents provide a predominate contribution to the differences between the free energies of single ion transfer calculated using the ferrocene and alternative extrathermodynamic assumptions. 相似文献
10.
Yu. Yu. Samitov N. K. Tazeeva N. A. Chadaeva G. Kh. Kamai 《Chemistry of Heterocyclic Compounds》1973,9(4):422-427
The configuration and conformations often 2-, 4-, and 5-substituted 1,3,2-dioxaarsenanes were studied from their PMR spectra. Inversion of the shielding constants of protons in the 4, 6, and 5 positions and of methyl groups in the 5 position was established, and the axial orientation of the As-Cl and As-OR bonds, the equatorial orientation of the 4-CH3 group, and the chair conformation of the six-membered heteroring were proved. The anisotropies of the diamagnetic susceptibility were estimated for the first time:
and
(dipole approximation);
and
(nondipole approximation). The cyclic torsion angle (= 58°) as found for 2-chloro-1,3,2-dioxaarsenane by the R-factor method. Conclusions regardiwng the conformation of the ring and substituents were confirmed by a study of the specific effect of an aromatic solvent on the position of the resonance lines.Communication I from the series Investigation of the Stereochemistry of Organic Arsenic Compounds by NMR Spectroscopy.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 457–463, April, 1973. 相似文献
11.
Because of their exceptional reactivity, fluorine and fluorinated gases are of primary importance for the modification of the surface properties of materials. This study is devoted to surface treatment of thin nitrile gloves, made of carboxylated nitrile butadiene rubber latex, using either direct fluorination (10% F2gas diluted in N2) or plasma-enhanced fluorination in radio-frequency cold plasmas using fluorinated gases (CF4, CHF3). Mechanisms of fluorination of these co-elastomers have been proposed on the basis of the assignment of the different components of the XPS spectra. Several mechanisms have been observed depending on the fluorination conditions. Although the modification of nitrile gloves is already effective for fluorination reactions at room temperature, an important activation is observed for experiments carried out at 90°C. When the treatments are carried out at room temperature, a gradual fluorination occurs: in the case of 10% diluted F2 gas, monofluorinated C—F groups are the species most found at the surface and perfluoro groups CF
n
are present in lower amount. An addition reaction takes place at the
CH=CH
double bonds of the polybutadiene entities, leading to
CHF=CHF
units. Whatever the fluorination method, thermal activation yields a more massive fluorination of the surface that finally leads to perfluorinated
CF2
groups and terminal —CF3 groups. 相似文献
12.
V. M. Bzhezovskii N. N. Il’chenko M. B. Chura L. G. Gorb L. M. Yagupol’skii 《Russian Journal of General Chemistry》2005,75(1):86-93
The potential functions of internal rotation around the C
-S bond in the C6H5S(O)CH3 and C6H5S(O)CF3 molecules were obtained by ab initio MP2(full)/6-31+G* calculations. The stationary points were identified by solving the vibrational problems. The structures in which the plane of the C
-S-C
bonds is approximately perpendicular to the benzene ring plane correspond to the energy minimum. The barriers to rotation around the C
-S bond, corrected for the zero-point vibration energy, are 21.29 [C6H5S(O)CH3] and 28.98 [C6H5S(O)CF3] kJ mol−1. The bond angles (deg) are as follows: 95.7 (CSC), 107.1 (C
SO), 106.3 (C
SO) in C6H5S(O)CH3; 93.5 (CSC), 108.2 (C
SO), 105.2 (C
SO) in C6H5S(O)CF3. The bond lengths are as follows (Å): 1.520 (S=O), 1.804 (C
-S), 1.810 (C
-S) in C6H5S(O)CH3; 1.507 (S=O), 1.799 (C
-S), 1.870 (C
-S) in C6H5S(O)CF3. According to the results of NBO calculations, the formally double S=O bond consists of a strongly polarized covalent σ bond (S→O) and an almost ionic bond. An increase in the S=O bond multiplicity relative to a single bond is mainly due to hyperconjugation by the mechanism n(O)→σ*(C
-S) and n(O)→σ*(C
-S) and, to a lesser extent, by interaction of the oxygen lone electron pairs with the Rydberg orbitals of the S atoms, characterized by a large contribution of the d component.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 96–104.Original Russian Text Copyright © 2005 by Bzhezovskii, Il’chenko, Chura, Gorb, Yagupol’skii. 相似文献
13.
I. S. Akhrem S. V. Reznichenko V. V. Grushin O. Yu. Simonova N. M. Chistovalova M. E. Vol'pin 《Russian Chemical Bulletin》1989,38(11):2229-2233
Reduction of OsO4 by molecular hydrogen in alkane (cycloalkane) or benzene (toluene) solution produces small-ligand clusters of osmium of composition Os1.5–2.5. CH0–2 with a particle size 10–40 Å and a specific surface area of 34–46 m2/g. Hydrogenation of dry catalyst produces methane. The small-ligand osmium clusters obtained effectively catalyze hydrogenolysis of alkanes and cycloalkanes at 100–150°C and
=5 MPa and hydrogenation of benzene at 20°C and
=0.1 MPa.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2428–2433, November, 1989. 相似文献
14.
Summary A new method is described for synthesizing aromatic -amino ketones with the general formula
, which is based on the condensation of azlactones with benzene in the presence of aluminum chloride. 相似文献
15.
V. V. Negrebetskii V. S. Bogdanov A. V. Kessenikh 《Journal of Structural Chemistry》1971,12(4):649-651
Conclusions The determination of the absolute values and signs of the SSIC
has great value both for investigating the electronic structure of organonitrogen compounds and for verifying and developing the theory of spin-spin interaction. It has been recently disclosed [8–10] that the magnitudes of the direct, geminal, and vicinal SSIC
depend on the dielectric constant of the solvent on its protonation. In addition, the sign of the geminal SSIC
in oximes depends on the configuration of the latter [8, 9].The signs of the SSIC that we determined agree with those found earlier for some organonitrogen compounds [6, 8, 11–15] and add to those mentioned above the instance when one of the protons, which is directly bonded to the nitrogen, froms an intramolecular hydrogen bond. It is interesting that the geminal SSIC
in compound II is zero. This agrees with the fact that the geminal SSIC changes sign upon passing through zero. At the same time, the vicinal SSIC JH-H differs from zero and is larger than the geminal SSIC JH-H in compound I.N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 12, No. 4, pp. 716–718, July–August, 1971. 相似文献
16.
Group contributions to
in seven solvents and to
in three solvents have been tabulated. The variation of
group parameters is discussed in terms of the solvent compressibility coefficient, T. The scaled particle theory (SPT) is used to calculate cavity contributions to
and C
p2
o
. Interaction contributions are obtained from the cavity terms and
and
values estimated through the additivity schemes.
values are more sensitive to solute-solvent interactions than
in water and less sensitive in methanol. The SPT results for heat capacities support the concept of structural promotion by hydrophobic solutes in water. 相似文献
17.
The conduction and transport numbers of charge carriers for composites in the systems MeWO4-WO3 (Me = Ca, Sr, Ba) are studied as a function of the temperature and the activity of oxygen in a gas phase. The transport numbers are determined by an emf method and are estimated from dependences of conductance on the activity of oxygen in a gas phase. The deficiencies of the given procedure as applied to investigation of properties of composite phases are analyzed. The materials under study are classified with a class of metacomposites. The concentration intervals of the ionic, mixed, and electronic conductions are determined. The conduction of composites of compositions (100 − x)MeWO4 ⋅ xWO3 is predominantly ionic at x ≤ 10 (Me = Ca), x ≤ 60 (Me = Sr), and x ≤ 45 (Me = Ba). The obtained data are explained in the framework of a model that represents a composite as a distributed matrix system where a film of surface phase MeW-s with a high mobility of oxygen ions plays the role of a connected matrix. It is presumed that the surface phase MeW-s possesses double-sided surface activity (α MeW-s ≤
) and a higher mobility with respect to MeWO4 and WO3. The discovered anomalies of dependences
(T) and partial dependences
, σel(T) are explained by a change in the stoichiometry, morphology, and the degree of connectedness of surface phase MeW-s caused by with a change in the temperature and composition of composites.__________Translated from Elektrokhimiya, Vol. 41, No. 6, 2005, pp. 680–693.Original Russian Text Copyright © 2005 by Neiman, Pestereva, Sharafutdinov, Kostikov.Published on the basis of a report delivered at the VII Meeting on Fundamental Problems in Solid-State Ionics (Chernogolovka-2004). 相似文献
18.
Summary The oxidation of H2O2 by [W(CN)8]3– has been studied in aqueous media between pH 7.87 and 12.10 using both conventional and stopped-flow spectrophotometry. The reaction proceeds without generation of free radicals. The experimental overall rate law,
, strongly suggests two types of mechanisms. The first pathway, characterized by the pH-dependent rate constant k
s, given by
, involves the formation of [W(CN)8· H2O2]3–, [W(CN)8· H2O2·W(CN)8]6– and [W(CN)8· HO]3– intermediates in rapid pre-equilibria steps, and is followed by a one-electron transfer step involving [W(CN)8·HO]3– (k
a) and its conjugate base [W(CN)8·O]4– (k
b). At 25 °C, I = 0.20 m (NaCl), the rate constant
with H
a
=40±6kJmol–1 and S
a
=–151±22JK–1mol–1; the rate constant
with H
b
=36±1kJmol–1 and S
b
=–136±2JK–1mol–1 at 25 °C, I = 0.20 m (NaCl); the acid dissociation constant of [W(CN)8·HO]3–, K
5
=(5.9±1.7)×10–10
m, with
and
is the first acid dissociation constant of H2O2. The second pathway, with rate constant, k
f, involves the formation of [W(CN)8· HO2]4– and is followed by a formal two-electron redox process with [W(CN)8]3–. The pH-dependent rate constant, k
f, is given by
. The rate constant k
7
=23±6m
–1
s
–1 with
and
at 25°C, I = 0.20 m (NaCl). 相似文献
19.
Solid-solute phase equilibria in aqueous solutions,VIII: The standard gibbs energy of La2(CO3)3·8H2O
Anh Mai Nguyen Erich Königsberger Harald Marhold Heinz Gamsjäger 《Monatshefte für Chemie / Chemical Monthly》1993,124(10):1011-1018
The solubilities of lanthanum carbonate La2(CO3)3·8H2O in solutionsS
0([H+]=H mol kg–1, [Na+]=(I–H) mol kg–1, [ClO
4
–
]=I mol kg–1) at various fixed partial pressures of CO2 have been investigated at 25.0 °C. The hydrogen ion molality and the total molality of La(III) ion in equilibrium with the solid phase were determined by e.m.f. and analytical methods, respectively. The stoichiometric solubility constants
相似文献
20.
Virender K. Sharma Fabien Casteran Frank J. Millero Concetta De Stefano 《Journal of solution chemistry》2002,31(10):783-792
The sulfur-containing biomolecule, cysteine has a role in physiological and natural environment because of its strong interactions with metals. To understand these interactions of metals with cysteine, one needs reliable dissociation constants for the protonated cysteine species [
CH(CH2SH)COOH; H3B+]. The values of dissociated constants, p
, for protonated cysteine species (H3B+ H+ + H2B, K
1; H2B H+ + HB–,K
2; HB– H+ + B2–,K
3) were determined from potentiometric measurements in NaCl solutions as a function of ionic strength, 0.5–6.0 mol-(kgH2O)–1 and between 5, and 45°C. The equations
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