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1.
Kassai Cs. Illés R. Pokol G. Sztatisz J. Fogassy E. Kozma D. 《Journal of Thermal Analysis and Calorimetry》2000,62(3):647-655
The resolution of three chiral alcohols with O,O'-dibenzoyl-(2R,3R)-tartaric acid (DBTA) via diastereoisomeric supramolecular
compound formation was investigated with thermoanalytical methods. On the basis of TG measurements the DBTA:chiral alcohol
molar ratio in the compounds is 1:1 which agrees with the results of single-crystal X-ray diffraction analysis. The DBTA –
chiral alcohol supramolecular compounds have different supramolecular structure than the DBTA – achiral alcohol supramolecular
compounds. The supramolecular compounds containing cyclohexanols have higher thermal stability than the compounds containing
acyclic aliphatic alcohols. The amount of unreacted DBTA monohydrate in the solid phase can be determined both with DSC and
with TG measurements.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Pter Bagi Konstantin Karaghiosoff Mtys Czugler Dra Hessz Mihly Kllay Mikls Kubinyi Tibor Szilvsi Pter Pongrcz Lszl Kollr Istvn Timri Katalin E. Kvr Lszl Drahos Elemr Fogassy Gyrgy Keglevich 《Heteroatom Chemistry》2016,27(2):91-101
An efficient resolution method was elaborated for the preparation of (+)‐4‐chloro‐5‐methyl‐1‐phenyl‐1,2,3,6‐tetrahydrophosphinine oxide using the acidic Ca2+ salt of (–)‐O,O‐di‐p‐toluoyl‐(2R,3R)‐tartaric acid. Crystal structure of the diastereomeric complex was evaluated by single crystal X‐ray analysis. Beside this, the absolute P‐configuration was also determined by a circular dichroism (CD) spectroscopic study including theoretical calculations. The tetrahydrophosphinine oxide was then converted to the corresponding platinum complex whose stereostructure was investigated by high‐level quantum chemical calculations. The Pt complex was tested as a catalyst in the hydroformylation of styrene. 相似文献
3.
Gbor Tth Elemr Fogassy Mria cs Lszl Tke Tibor Lng 《Journal of heterocyclic chemistry》1983,20(3):709-713
A process has been developed for resolving 1 , and the anomalous behaviour of the specific rotation of the enantiomers has been studied. It was shown that this is due to the shift in the conformational equilibrium la ? Ib , and not to an epimerization at C-5. 相似文献
4.
With the advantage of the method using two immiscrible solvents and half - equivalent amount of the resolving agent, higher optical purity can be obtained than in cases of any other resolution via diastereoisomeric salt formation, besides it is a faster procedure for resolution of a new racemate as well. 相似文献
5.
As a consequence of homo- and heterochiral interactions in solutions of enantiomer mixtures selective reactions and separations can be achieved. Possibilities of selective separations and their characteristic properties were studied. On the basis of the common features of the investigated procedures selective separations can be planned. 相似文献
6.
Katalin Nemák Mária Ács D. Kozma E. Fogassy 《Journal of Thermal Analysis and Calorimetry》1997,48(3):691-696
The phenomena of conglomerate formation-racemic compound formation were investigated in a series of five (N-alkyl)-2,6-pipecoloxylidides. The optically active enantiomers were prepared by optical resolution of the racemates using 2R,3R-tartaric acid and 0,0-dibenzoyl-2R,3R-tartaric acid as resolving agent. By DSC measurement of the racemates and the enantiomer the binary phase diagrams were determined.Among the four racemic molecular compounds the N-methyl derivative is the more stable. By increasing the length of the alkyl chain the stability of the racemic compound decreased, and in case of the longest -butyl-chain conglomerate formation was observed.Part 3. D. Kozma, Zs. Böcskei, Cs. Kassai, K. Simon and E. Fogassy: Racemic Compound Formation-Conglomerate Formation. Part 3. Investigation of the Acidic Salts of -phenylethylamine by Achiral Dicarboxylic Acids. Optical Resolution by Preferential Crystallization and a Structural Study of R--phenylethylammonium hydrogen ithaconate, J. Chem. Soc. Perkin Trans. 2 (1996) 1511.The authors are grateful for financial support to OTKA foundation (grant numbers: F14851 (D. K.), T14887 (E. F.)) and for the Z. Magyary award for D. K. 相似文献
7.
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
8.
H. Simon K. Marthi Gy. Pokol E. Fogassy D. Kozma 《Journal of Thermal Analysis and Calorimetry》2003,74(1):155-162
O,O'-di-p-toluoyl-(2R,3R)-tartaric acid (DPTTA) was investigated as supramolecular complex (SMC) forming resolving agent with three racemic alcohols
(menthol, 4-methyl-2-pentanol, trans-2-iodo-cyclohexanol) by preparative scale experiments and thermoanalytical measurements.
Despite the very small structural difference (two methyl groups) between the O,O'-dibenzoyl-(2R,3R)-tartaric acid (DBTA) and DPTTA, their SMC forming properties with water and racemic alcohols is very different. While DBTA
forms SMC with all the three investigated alcohols, DPTTA forms SMC only with trans-2-iodo-cyclohexanol. DPTTA binds the guest compound less strongly and the stoichiometry of the SMC is also different. The
weaker interactions resulted in less effective optical resolutions. The results of these investigations remind us, that in
optical resolutions during the chiral discrimination process the weaker interactions have a determining role, since DBTA and
DPTTA have the possibility to form the same strong (O-H···O and N-H···O) hydrogen bond network.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
M. ács Gy. Pokol F. Faigl E. Fogassy 《Journal of Thermal Analysis and Calorimetry》1988,33(4):1241-1245
Crystallization from the melt was applied to separate components of stereoisomeric mixtures. Binary phase diagrams were determined by DSC and used in the design of the crystallization process. The method is illustrated by the separation of diastereoisomeric (cis-trans) permethrinic acid and by that of the enantiomeric excess and racemic fraction of the Corey-lacton.
Zusammenfassung Zur Abtrennung von Komponenten aus stereoisomeren Mischungen wurde die Kristallisation aus der Schmelze verwendet. Die binären Schmelzdiagramme wurden mittels DSC untersucht und zur Festlegund der Parameter des Kristallisations-prozesses genutzt. Die Methode wird-erläutert an den Beispielen (1) Trennung der Diastereomeren (cis/trans) Permethrinsäuren, (2) Abtrennung des Enantiomeren-überschusses von racemischem Corey-Lacton.
. , . (-) .相似文献
10.
Kozma D. Simon H. Pokol Gy. Fogassy E. 《Journal of Thermal Analysis and Calorimetry》2002,69(2):409-416
The enantiomeric enrichment of N-methyl-amphetamine (MA) was tried by eight different preparative separation methods. The enrichment process was also studied by thermoanalitical methods (DSC,TG). There is no enantiomeric enrichment during fractional distillation and selective extraction of the liquid base. The enantiomeric mixture of MA·HCl can be enriched by crystallization or by sublimation. The most effective enrichment can be achieved by fractional crystallization or distillation of the reaction mixture after partial salt formation with hydrochloric acid. The separation is less effective in case of fractional steam distillation and selective extraction when the enantiomer and the racemate are distributed between two liquid phases. This supports the general experience that having a solid phase in the system makes enantiomer separation more efficient.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献