The molecular-sieve properties of a number of synthetic and natural chabazites have been investigated.
2.
Characteristic differences have been revealed in the molecular-sieve properties, thermal stability, and x-ray characteristics between the two groups of the zeolites studied.
3.
A reversal of the molecular-sieve effect on passing from the calcium to the sodium-calcium forms of certain synthetic and natural chabazites has been observed.
The auto- and cross-correlation times of reorientation of the CH vectors of molecules, determined by13C nuclear magnetic relaxation, and the calculations based on the modified Kirkwood-Steele-Huntress theory make it possible to determine the most probable conformations of molecules containing OH groups.
2.
The mobility parameters of molecules in water can be calculated within the framework of the modified Kirkwood-Steele-Huntress theory using the proposed model of effective reactions.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1281–1287, June, 1988. 相似文献
A new organophosphorus complexing agent, N,N-di-(2-hydroxyethyl)ethylenediaminodimethylphosphonic acid was synthesized, which contains additional functional hydroxyl groups in the alkyl radicals on the nitrogen atoms.
2.
The acid and complex-forming properties for this complexing agent were studied. The composition was studied for the complexes using the methods of spectrophotometry, and high-frequency titration.
On Raney Cu and Co catalysts modified with D-(+)-tartaric acid acetoacetic ester is hydrogenated asymmetrically.
2.
The optical yield of (-)-ethyl-3-hydroxybutyrate depends on the nature of the catalyst and the experimental conditions: on Cu catalyst the optical yield reaches 20–24% and is close to the optical yield obtained on modified Ni catalyst: on Co catalyst the optical yield is considerably less (2–8%). With increase in the quantity of catalyst the optical yield on these catalysts passes through a maximum.
Four analogues of LH-RH modified in position 5 have been synthesized using either classical procedures or the solid phase method. The gonadotropin-releasing activities were determined by radioimmunological measurements of LH and FSH in vivo and in vitro and the immunoreactivities by a specific LH-RH radioimmunoassay (RIA). The following relative potencies and immunoractivities were found:
in vivo
in vitro
Immuno-reactivity
LH-RH:
100 %
100 %
100 %
[Tyr(Me)5]
-LH-RH:
8.6%
6.0%
40.0%
[Phe5]
-LH-RH:
42.5%
27.5%
17.0%
[Cha5]
a Abbreviations were used according to [37]; Cha = cyclohexyl-L-alanine.
The catalytic properties of iron nitride (Fe2N) and carbonitride (Fe2C0.29N0.71) in the reactions of amination and dehydrogenation of alcohols were compared.
2.
In the course of the amination and dehydrogenation reactions on a nitride catalyst, there is an elution of part of the introduced nitrogen from the surface with the formation of the structure of the lower nitride.
3.
For related structures of the nitride and carbonitride, a correlation was detected between the catalytic activity and the average magnetic moment of the iron atom in the alloy.
A practicable method for the synthesis of vicinal bis(difluoramino)-containing carboxylic acids by reacting tetrafluorohydrazine with unsaturated acids has been developed.
2.
,-Bis(difluoramino)carboxylic acids are unstable and undergo decarboxylation followed by dehydrofluorination.
3.
,-Bis(difluoramino)carboxylic acids are fairly stable and in some cases display the properties of ordinary carboxylic acids.
The adducts of N-benzenesulfonylbis(trifluoromethyl)ketenimine with either KF or KHF2 are formed when perfluoroisobutylene is reacted with the K salt of benzenesulfonamide.
2.
N-Benzenesulfonylbis(trifluoromethyl)ketenimine was synthesized and some of its properties were studied.
An increase in the SiO2/Al2O3 ratio (x) in type Y zeolites through dealuminization with ethylenediaminetetraacetic acid leads to an increase in their catalytic activity during the alkylation of benzene with ethylene.
2.
The properties of CaNaY zeolites of the same composition prepared from NaY obtained by hydrothermal synthesis and by dealuminization of samples with a small value of x are identical.
3.
Carbon dioxide exerts an accelerating effect on the Ca forms of dealuminized type Y zeolites of various compositions and has no effect on the properties of NaY'.
Presently, a large variety of layered materials are synthesized that are able to intercalate neutral guest molecules or to exchange inorganic and organic ions for interlayer ions. Several of these materials are also found as minerals.The intracrystalline reactivity of a few selected compounds will be described and compared to clay minerals:
–
- intercalation into crystalline silicic acids;
–
- reactions of phosphates, arsenates, and sulfates;
–
- reactions of titanates, niobates, and molybdates with long chain alkylammonium ions, and
Bimetallic powdered nickel-cobalt catalysts differing in composition and modified by RR-(+)-tartaric acid were studied in the asymmetric hydrogenation of ethyl acetoacetate.
2.
The optical yield of this reaction is increased to 54% with an increase in the nickel content in the Ni-Co catalyst to 90% and is 60–65% for the nickel catalyst.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1172–1174, May, 1988. 相似文献
The adsorption properties with respect to benzene vapors and the pore structure of carbon adsorbents with almost maximum development of the microporosity were studied.
2.
The position of the micropore volume distribution curves whose maxima correspond to a size (halfwidth) of 1.2–1.4 nm and micropore volumes 1.5 cm3/g is a characteristic feature of the adsorbents studied. The difference between ordinary active carbons and the active carbons investigated is only quantitative in the values of the parameters of the Dubinin-Stockley adsorption equation.
3.
The adsorption isotherms are described by the adsorption equation from the theory of volume filling of micropores in a wide range of equilibrium relative pressures and temperatures of 293–353 K with totally satisfactory precision.
4.
The question of the upper limit of the micropores of carbon adsorbents is discussed.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 977–983, May, 1988. 相似文献
The Rasberry-Heinrich and Claisse-Quintin equations give a good interpretation of the theoretical intensity-concentration relationship in x-ray fluorescence spectrometry. The influence constants (Ax, Ax) of these equations can be calculated. Trace element and structural effects require an empirical correction, which is important in iron-copper-sulfur systems (reverberatory mattes and copper concentrates). The empirical correction in combination with either of the above equations can furnish very good quantitative results from fluorescence intensity measurements.
Most of the iron and copper was present as FeS and Cu2S, respectively; W is the “wet” method. Concentrates I and II contained 6.0% SiO2-2.2% Al2O3 and 4.6% SiO2-1.8% Al2O3, respectively (average values).
A direct amperometric titration of copper is described; o-(p-tolylsulfonamido) aniline serves as titrant. The optimum conditions are discussed and the method is applied to the analysis of copper in brass alloys.
t001. IV. Analysis of various samples in which copper was determined (Values given as percentages)
The Coulometrics Inc. CO2 coulometer has been shown to be an accurate and reliable CO2 measuring device. The coulometric efficiency is essentially 100%. This means that the method can be considered as a standard reference method for CO2. As with a CO2 absorption tube, certain potential interferences must be considered, however, the removal of these interferences is well documented in the literature.The CO2 coulometer has found a variety of applications in the author's
3. effect of flow rate on absorption of CO2 by coulometer
A new batch titration microcalorimeter has been used for estimation of thermodynamic properties in various investigated colloidal systems. As examples, we present enthalpic and kinetic data obtained from this calorimetric device for four different processes widely encountered in colloid science:
(i)
The dilution/micellization process of cationic gemini surfactants in aqueous solution.
(ii)
The hydration process of non ionic surfactants in organic solution, i.e. the mechanism of micellar solubilization of water in the aggregates.
(iii)
The complexation of calcium ions by polyacrylates sodium salts (PaNa).
(iv)
The adsorption phenomenon of PaNa molecules on the calcium carbonate surface.
This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
Multielement determinations by high-flux absolute n.a.a. require careful methodology to avoid systematic error. The ORNL high-flux facility with a thermal flux of 5 ·1014 cm-2 s-1 and a thermal-to-resonance flux ratio of
Results in p.p.m followed by (per cent counting statistical error).
b
Computer forced result.Also V,Se,Sr,Sb,Cs and au (forced) were not detected.
c
Element possibly present but missed by peak-finding routine.7 35–45, was used in developing an instrumental absolute multielement method. The detector was calibrated for absolute counting with two independent sets of radioactivity standards for four detector- -source distances; the absolute activities of the standards were reproducible within accuracies of 9%. Five sources of systematic error were investigated: (a) correction for counting of cylindrical sources for 26 γ-ray energies reached 14–17% for photon energies below 500 keV; (b) flux variation during bombardment and within the irradiation capsule volume was not significant; (c) samples were sufficiently stable during high-flux bombardment; (d) multi-element impurities in accessory materials (polyethylene and “Nucleopore” filters) were not significant; (e) correction for sample activation during rabbit transfer was necessary for short bombardments, e.g., 8.6 % for 6 s and 19.6 % for 4 s. This methodology resulted in accuracies of 10–15 % for most elements, as determined by analysis of N.B.S. orchard leaves and coal and of Bowen's kale standards. The method was applied to a preliminary chronological study of environmental baselines and contamination levels, based on tree ring samples, covering a period of 100 years.
The strong bathochromic shift of the absorption bands of aminoazo compounds in acid medium is due to the formation of a cation of quinoid structure.
2.
Aminoazo compounds are weak NH acids in aprotic polar solvents, and they form the corresponding mesomeric anions in the presence of alkalis.
3.
The synthesized aminoazo compounds are very weak NH acids, and electron-donor substituents weaken the acid properties of the amino group, while electron-acceptor substituents intensify them.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1513–1518, July, 1989. 相似文献
When silicas are modified with amines, not all surface silanol groups participate in the chemical reaction.
2.
When amine-modified silica gels are heated, water is produced; the maximum rate of the formation of gas occurs at 625 and 750 K. Destruction of the modifying layer begins with the liberation of ammonia at T > 640 K.
3.
Adsorption of SO2 and CO2 on aminated silicas is determined by the surface concentration of amino groups, by their nature, and by their mutual position.
Translated from Izvestiya Akademiya Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 983–990, May, 1989. 相似文献
Nitron and tetraphenylarsonium chloride react with a cobaltous salt in the presence of thiocyanate to form blue ion-association complexes, which can be extracted with organic solvents. This fact has been made the basis for the analysis of mixtures of nitrate and perchlorate by difference spectrophotometry. An aliquot of the sample solution is treated with a known excess of tetraphenylarsonium chloride to precipitate perchlorate only. After separating off the precipitate, the excess of reagent is determined in the supernatant liquid as tetraphenylarsonium cobaltothiocyanate and the perchlorate content can be found from a calibration curve. Another aliquot is treated with an excess of nitron to precipitate both anions; the excess of nitron is then determined as nitron
