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1.
V. M. Leovac E. Z. Ivegeš K. Mészáros Szécsényi K. Tomor G. Pokol S. Gal 《Journal of Thermal Analysis and Calorimetry》1997,50(3):431-440
Solvate complexes of UO 2 2+ andN(1), N(4)-bis(salicylidene)-S-methylisothiosemicarbazone, (H2Me-L1), of general formula [UO2(Me-L1)S] (S= H2O, MeOH, EtOH, Py, DMF and DMSO) were synthesized. The methanolic UO 2 2+ ” adducts of N(1)-benzoylisopropylidene-N(4)-salicylidene-S-alkylisothiosemicarbazone, (H2R-L2,R=Me, Prn) of general formula [UO2(R-L2)· MeOH], were also prepared. Thermal decomposition of the complexes was investigated in air and argon. The complexes decompose to α-U3O8 in air, while in argon the decomposition is not completed up to 1000 K. The temperature and the mechanism of decomposition of the complexes are a function of the solvent belonging to the inner coordination sphere. 相似文献
2.
K. Mészáros Szécsényi K. Tomor G. Pokol 《Journal of Thermal Analysis and Calorimetry》1994,41(1):125-134
The phase diagram for the AgNO3?KNO3 system has been determined using differential scanning calorimetry (DSC). Eutectic point has been found at 391 K andX Ag=0.580 mole fraction AgNO3. The DSC curves indicate the existence of an intermermediate compound (AgNO3·KNO3) in the KNO3-rich region of the phase diagram. This compound was identified in the solid phase by X-ray diffraction. The melting and the crystallization processes were followed with the aid of a hot stage microscope, too. 相似文献
3.
J. Kőmives S. Gál K. Tomor Gy. Kovács 《Journal of Thermal Analysis and Calorimetry》1983,27(2):315-324
Thermogravimetry was applied in studies of aluminium foils for electrolytic capacitors. Scanning electron microscopy, X-ray diffraction and surface area determination were also used in the interpretation of the results. Both the specific surface area and the capacity of the foils showed a linear relationship to the height of the oxidation step measured by TG, which was found suitable for following the processes of anodic oxidation and thermal treatment of the foils as well. 相似文献
4.
J. KŐmives K. Tomor J. Sztatisz L. Lassu S. Gál 《Journal of Thermal Analysis and Calorimetry》1984,29(5):1083-1093
Changes in the water content of aluminium sulphate hydrate were investigated gravimetrically at room temperature in air with different relative humidities. The samples conditioned in this way were characterized by thermoanalytical (TG, DTG, DSC) and X-ray diffraction measurements. Industrial aluminium sulphate hydrate obtained by freezing the melt has a partly crystalline structure. After grinding, this material crystallizes during storage. This process requires a humid atmosphere; increasing relative humidity brings about more intensive crystallization.It was found that the crystallization of aluminium sulphate from the melt is facilitated by a higher water content of the melt.
Zusammenfassung VerÄnderungen des Wassergehalts von Aluminiumsulfat-Hydrat bei Zimmertemperatur in Luft unterschiedlicher relativer Feuchtigkeit wurden gravimetrisch untersucht. Die auf diese Weise konditionierten Proben wurden durch thermoanalytische (TG, DTG, DSC) und röntgendiffraktometrische Messungen charakterisiert. Durch Erstarren der Schmelze erhaltenes industrielles Aluminiumsulfat-Hydrat ist teilweise kristallin. Nach dem Mahlen kristallisiert dieses Material wÄhrend der Lagerung. Dieser Proze\ erfordert eine feuchte AtmosphÄre, wobei sich der Kristallisationsgrad mit steigender relativer Feuchtigkeit erhöht. Es wurde festgestellt, da\ die Kristallisation des Aluminiumsulfats durch einen höheren Wassergehalt der Schmelze gefördert wird.
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5.
Kozma D. Novák Cs. Tomor K. Pokol Gy. Fogassy E. 《Journal of Thermal Analysis and Calorimetry》2000,61(1):45-50
The optical resolution of α-phenylethylamine (1) by 2R,3R-tartaric acid (2) was studied in different solvents, the precipitated
salts were subjected to thermoanalytical measurements and X-ray powder diffraction. The most efficient resolution can be accomplished
by using methanol, the precipitate, an unsolvated salt containing the S-(-)-1⋅2R,3R-(+)-2 salt in abundance, is not a simple
mixture of the diastereoisomeric salt pair, but a new modification. In water, ethanol and acetonitrile a reversed, but less
effective resolution can be accomplished by precipitation of a hydrate which contains the R-(+)-1 in abundance. The precipitates
from water and ethanol also proved to be new modifications. Only the precipitate from acetonitrile is the mixture of the diastereoisomeric
salt pair, which can be expected in fractional crystallization of an eutectic forming diastereoisomeric salt pair. The number
of different modifications found by changing the solvent in case of this particular salt pair seems surprisingly high, but
may occur for other diastereoisomeric salt pairs, too. The existing but not investigated polymorphism can be the explanation
for the sometimes very poor reproducibility of the preparative resolutions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
D. Kozma Klára Tomor C. Novák G. Pokol E. Fogassy 《Journal of Thermal Analysis and Calorimetry》1996,46(6):1613-1623
Racemic malic acid (I) was resolved by R-α-phenylethylamine(II). The S-(?)-I.R-(+)-II diastereoisomer was in excess in the precipitated salt. DSC curves and X-ray powder diffractograms proved that the diastereoisomeric salt mixture precipitated during the resolution was isomorphous with the optically pure S-(?)-I.R-(+)-II salt. The diastereoisomeric salt mixture containing the R-(?)-I.R-(+)-II salt in abundance bound crystal solvate (water or methanol) when produced by the total evaporation of the mother liquor, while the optically pure R-(?)-I.R-(+)-II salt crystallized without solvate. It is generally assumed that solid solution formation takes place when the two diastereoisomers are alike and the high similarity results in less efficient enantiomer separation. This paper demonstrates that efficient resolution can be accomplished in case of solid solution formation too. The diastereoisomeric salt mixtures can crystallize in isomorphic form even when the physico-chemical properties of the optically pure diastereoisomeric salts are quite different. 相似文献
7.
M. Fodor Cs. Novák R. Ràkosa K. Tomor G. Pokol S. Gál 《Journal of Thermal Analysis and Calorimetry》1997,48(3):515-525
In the present study the solid and liquid phase behaviour of mandelic acid cyclodextrin systems were studied. The samples were prepared using dry grinding/kneading technique in the absence of any solvent. Thermoanalytical methods (TG, DSC, EGD) were used to characterise the solid compounds. In liquid phase the stoichiometry and the stability constants of the complexes formed were determined using UV spectrophotometry. Partial complex formation was found in case of all cyclodextrins used. The amount of uncomplexed mandelic acid varied between 10–20% of the total guest content. 相似文献
8.
K. Mészáros Szécsényi M. Arnold K. Tomor F. F. Gaál 《Journal of Thermal Analysis and Calorimetry》1995,44(2):419-430
The thermal behavior of different fly ashes from the electrical precipitators of various pulverized carbon fuel-fired boilers was investigated by means of simultaneous TG, DTG, DTA and EGA analysis. The carbon and sulfur contents of the samples were determined by gastitrimetry. The compositions of the samples were examined by X-ray diffraction. The quantitative oxide analysis of the ashes was carried out by means of a classical method. 相似文献
9.
D. Kozma J. Sztatisz K. Tomor G. Pokol E. Fogassy 《Journal of Thermal Analysis and Calorimetry》2000,60(2):409-415
The optical resolution of racemic mandelic acid (I) by S-2-benzylamino-butanol (II) was performed in water, ethyl acetate,
and water saturated ethyl acetate. It was found that the efficiency of the resolution is three times higher in water saturated
ethyl acetate than in either water or ethyl acetate. The salt mixtures produced during the resolutions and the pure diastereoisomeric
salts were analyzed by TG, DSC and X-ray powder diffraction measurements. The R-(-)-I×S-(+)-II salt has the higher melting
point and heat of fusion value which indicates that this is the more stable salt. Though the general assumption is that diastereoisomeric
salt pairs of successful optical resolutions form eutectic systems, the R-mandelic acid-S-2-benzylamino-butanol and the S-mandelic
acid-S-2-benzylamino-butanol system was found to behave in a different way. Melting did not start at or near the estimated
eutectic temperature. The difference can be explained either by miscibility in the solid phase (solid solution) or by a blocked
interaction between the crystals of the two solid salts. This unusual behaviour of the salt pair should be responsible for
the unusual difference in the efficiency of the resolutions performed in different solvents
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
S. Békássy T. Cseri G. Kenessey G. Pokol K. Tomor G. Liptay 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1285-1292
Montmorillonite-supported iron(III) nitrate and copper(II) nitrate reagents, and other supported metal nitrates prepared in the same way, were investigated by thermal and X-ray powder diffraction methods. The metal nitrates are present on the support in the form of crystalline hydrate and not as acetone solvate as supposed earlier. Thermal decomposition of metal nitrates that are active in model reactions proceeds in a different way from that of the practically inactive nitrates. In the former case, water release and nitrate decomposition itself are simultaneous process. These and other results contributed to determination of suitable reaction conditions for the montmorillonite-supported reagents. 相似文献