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Samuel Kofi Tulashie - One of the best experts on this subject based on the ideXlab platform.
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solid liquid equilibria of n Methylephedrine enantiomers and their mixtures in two chiral ionic liquids
Journal of Chemical & Engineering Data, 2019Co-Authors: Samuel Kofi Tulashie, Heike LorenzAbstract:Solubility equilibria of the chiral N-Methylephedrine species in two chiral ionic liquids, (S)-2-(methoxycarbonyl) pyrrolidinium bis(trifluoromethylsulfonyl) amide ([(S)-2-Pro-Me][NTF2]) and (1R,2S...
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solid phase and oscillating solution crystallization behavior of and n Methylephedrine
Journal of Pharmaceutical Sciences, 2016Co-Authors: Samuel Kofi Tulashie, D. Polenske, Andreas Seidelmorgenstern, Heike LorenzAbstract:This work involves the study of the solid-phase and solution crystallization behavior of the N-Methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-Methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-Methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed.
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Solid-Phase and Oscillating Solution Crystallization Behavior of (+)- and (−)-N-Methylephedrine
Journal of pharmaceutical sciences, 2016Co-Authors: Samuel Kofi Tulashie, D. Polenske, Andreas Seidel-morgenstern, Heike LorenzAbstract:This work involves the study of the solid-phase and solution crystallization behavior of the N-Methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-Methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-Methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed.
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Solid−Liquid Equilibria of N-Methylephedrine Enantiomers and Their Mixtures in Three Chiral Solvents Distinguished by Chain Length
Journal of Chemical & Engineering Data, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Andreas Seidel-morgensternAbstract:Solubility equilibria of the chiral N-Methylephedrine species in three chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have systematically been studied. Solubility measurements were performed for enantiomeric compositions ranging from 1:1 mixtures to the pure enantiomer and at temperatures between (273 and 298) K. The influence of increasing chain length of the chiral solvents on solubility has been evaluated.
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solid liquid equilibria of n Methylephedrine enantiomers and their mixtures in three chiral solvents distinguished by chain length
Journal of Chemical & Engineering Data, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Andreas SeidelmorgensternAbstract:Solubility equilibria of the chiral N-Methylephedrine species in three chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have systematically been studied. Solubility measurements were performed for enantiomeric compositions ranging from 1:1 mixtures to the pure enantiomer and at temperatures between (273 and 298) K. The influence of increasing chain length of the chiral solvents on solubility has been evaluated.
Heike Lorenz - One of the best experts on this subject based on the ideXlab platform.
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solid liquid equilibria of n Methylephedrine enantiomers and their mixtures in two chiral ionic liquids
Journal of Chemical & Engineering Data, 2019Co-Authors: Samuel Kofi Tulashie, Heike LorenzAbstract:Solubility equilibria of the chiral N-Methylephedrine species in two chiral ionic liquids, (S)-2-(methoxycarbonyl) pyrrolidinium bis(trifluoromethylsulfonyl) amide ([(S)-2-Pro-Me][NTF2]) and (1R,2S...
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solid phase and oscillating solution crystallization behavior of and n Methylephedrine
Journal of Pharmaceutical Sciences, 2016Co-Authors: Samuel Kofi Tulashie, D. Polenske, Andreas Seidelmorgenstern, Heike LorenzAbstract:This work involves the study of the solid-phase and solution crystallization behavior of the N-Methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-Methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-Methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed.
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Solid-Phase and Oscillating Solution Crystallization Behavior of (+)- and (−)-N-Methylephedrine
Journal of pharmaceutical sciences, 2016Co-Authors: Samuel Kofi Tulashie, D. Polenske, Andreas Seidel-morgenstern, Heike LorenzAbstract:This work involves the study of the solid-phase and solution crystallization behavior of the N-Methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-Methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-Methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed.
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Solid−Liquid Equilibria of N-Methylephedrine Enantiomers and Their Mixtures in Three Chiral Solvents Distinguished by Chain Length
Journal of Chemical & Engineering Data, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Andreas Seidel-morgensternAbstract:Solubility equilibria of the chiral N-Methylephedrine species in three chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have systematically been studied. Solubility measurements were performed for enantiomeric compositions ranging from 1:1 mixtures to the pure enantiomer and at temperatures between (273 and 298) K. The influence of increasing chain length of the chiral solvents on solubility has been evaluated.
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solid liquid equilibria of n Methylephedrine enantiomers and their mixtures in three chiral solvents distinguished by chain length
Journal of Chemical & Engineering Data, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Andreas SeidelmorgensternAbstract:Solubility equilibria of the chiral N-Methylephedrine species in three chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have systematically been studied. Solubility measurements were performed for enantiomeric compositions ranging from 1:1 mixtures to the pure enantiomer and at temperatures between (273 and 298) K. The influence of increasing chain length of the chiral solvents on solubility has been evaluated.
Andreas Seidelmorgenstern - One of the best experts on this subject based on the ideXlab platform.
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solid phase and oscillating solution crystallization behavior of and n Methylephedrine
Journal of Pharmaceutical Sciences, 2016Co-Authors: Samuel Kofi Tulashie, D. Polenske, Andreas Seidelmorgenstern, Heike LorenzAbstract:This work involves the study of the solid-phase and solution crystallization behavior of the N-Methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-Methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-Methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed.
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solid liquid equilibria of n Methylephedrine enantiomers and their mixtures in three chiral solvents distinguished by chain length
Journal of Chemical & Engineering Data, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Andreas SeidelmorgensternAbstract:Solubility equilibria of the chiral N-Methylephedrine species in three chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have systematically been studied. Solubility measurements were performed for enantiomeric compositions ranging from 1:1 mixtures to the pure enantiomer and at temperatures between (273 and 298) K. The influence of increasing chain length of the chiral solvents on solubility has been evaluated.
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solid liquid phase equilibria of n Methylephedrine enantiomers in two chiral solvents
Journal of Chemical & Engineering Data, 2010Co-Authors: Henning Kaemmerer, Samuel Kofi Tulashie, Heike Lorenz, Andreas SeidelmorgensternAbstract:The ternary solubility phase diagrams of the N-Methylephedrine species in two chiral solvents, (S)-ethyl lactate and (2R,3R)-diethyl tartrate, have been studied. Solubility measurements were performed for enantiomeric compositions and temperatures ranging from 1:1 mixtures to the pure enantiomer and from (273 to 313) K. Predicted ideal solubility curves of the N-Methylephedrine species in both solvents revealed deviations from experimental data. The nonrandom two-liquid model was applied to quantify and parametrize these nonidealities and nonideal heterochiral interactions among the enantiomers by means of corresponding activity coefficients. The solvent−solute interactions were interpreted as nonchiral specific, since no asymmetry in the chiral systems were found. The selection of an appropriate solvent for a crystallization-based enantioseparation based on the shape of solubility isotherms is discussed.
Andreas Seidel-morgenstern - One of the best experts on this subject based on the ideXlab platform.
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Solid-Phase and Oscillating Solution Crystallization Behavior of (+)- and (−)-N-Methylephedrine
Journal of pharmaceutical sciences, 2016Co-Authors: Samuel Kofi Tulashie, D. Polenske, Andreas Seidel-morgenstern, Heike LorenzAbstract:This work involves the study of the solid-phase and solution crystallization behavior of the N-Methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-Methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-Methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed.
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Solid−Liquid Equilibria of N-Methylephedrine Enantiomers and Their Mixtures in Three Chiral Solvents Distinguished by Chain Length
Journal of Chemical & Engineering Data, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Andreas Seidel-morgensternAbstract:Solubility equilibria of the chiral N-Methylephedrine species in three chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have systematically been studied. Solubility measurements were performed for enantiomeric compositions ranging from 1:1 mixtures to the pure enantiomer and at temperatures between (273 and 298) K. The influence of increasing chain length of the chiral solvents on solubility has been evaluated.
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Solid−Liquid Phase Equilibria of N-Methylephedrine Enantiomers in Two Chiral Solvents
Journal of Chemical & Engineering Data, 2010Co-Authors: Henning Kaemmerer, Samuel Kofi Tulashie, Heike Lorenz, Andreas Seidel-morgensternAbstract:The ternary solubility phase diagrams of the N-Methylephedrine species in two chiral solvents, (S)-ethyl lactate and (2R,3R)-diethyl tartrate, have been studied. Solubility measurements were performed for enantiomeric compositions and temperatures ranging from 1:1 mixtures to the pure enantiomer and from (273 to 313) K. Predicted ideal solubility curves of the N-Methylephedrine species in both solvents revealed deviations from experimental data. The nonrandom two-liquid model was applied to quantify and parametrize these nonidealities and nonideal heterochiral interactions among the enantiomers by means of corresponding activity coefficients. The solvent−solute interactions were interpreted as nonchiral specific, since no asymmetry in the chiral systems were found. The selection of an appropriate solvent for a crystallization-based enantioseparation based on the shape of solubility isotherms is discussed.
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Ternary Solubility Phase Diagrams of Mandelic Acid and N-Methylephedrine in Chiral Solvents with Different Carbon Chain Lengths
Crystal Growth & Design, 2010Co-Authors: Samuel Kofi Tulashie, Heike Lorenz, Chandrakant Ramkrishna Malwade, Andreas Seidel-morgensternAbstract:Ternary solubility phase diagrams of mandelic acid and N-Methylephedrine species in chiral solvents, (S)-methyl lactate, (S)-propyl lactate, and (S)-butyl lactate, have been determined. Solubility measurements were performed for enantiomeric compositions ranging from 50:50 mixtures to the pure enantiomers and temperatures ranging from 0 to 35 °C for mandelic acid and from 0 to 25 °C for N-Methylephedrine, respectively. The ternary solubility phase diagrams of mandelic acid and N-Methylephedrine showed symmetric behavior. It became obvious that increasing chain length of chiral solvents, i.e. from (S)-methyl lactate to (S)-butyl lactate, resulted in decreasing solubility. 1HNMR and Raman spectroscopy have been applied to characterize the solute-solvent interaction in the liquid phase for mandelic acid system. Molecular modeling calculations were performed for mandelic acid to get a deeper understanding of the solute−solvent interactions. The effect of the solvent on the shape of the solubility isotherms is...
Ulrike Holzgrabe - One of the best experts on this subject based on the ideXlab platform.
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Study on the chiral recognition of the enantiomers of ephedrine derivatives with neutral and sulfated heptakis(2,3-O-diacetyl)-β-cyclodextrins using capillary electrophoresis, UV, nuclear magnetic resonance spectroscopy and mass spectrometry
Journal of Chromatography A, 2001Co-Authors: C Hellriegel, H Händel, M Wedig, S Steinhauer, F Sörgel, K Albert, Ulrike HolzgrabeAbstract:The enantiomers of Methylephedrine, pseudoephedrine and ephedrine showed a different migration behavior in capillary electrophoresis in the presence of β-cyclodextrin (β-CD), heptakis(2,3-O-diacetyl)-β-cyclodextrin and heptakis(2,3-O-diacetyl-6-sulfato)-β-cyclodextrin (HDAS). Utilizing UV, MS and NMR spectroscopy, in particular rotating frame Overhauser experiments, an attempt was made to elucidate the chiral recognition mechanism. In the case of the neutral CDs 1:1 complexes were formed with ephedrine and Methylephedrine characterized by the inclusion of the phenyl ring in the cavity and the side chain pointing out of the wider rim. In contrast, manifold complexes were formed with HDAS, which on average are characterized by an upside down inclusion of the phenyl ring in the cavity and the side chain pointing out of the narrow rim. This complex geometry is likely be stabilized by an ion–ion interaction between the positively charged nitrogens of the ephedrine derivatives and the negative charges of HDAS. In addition, an attachment of the ligand to the outside of HDAS and other complex stoichiometries are also possible.
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Chiral discrimination by NMR spectroscopy of ephedrine and N-Methylephedrine induced by β-cyclodextrin, heptakis(2,3-di-O-acetyl)β-cyclodextrin, and heptakis (6-O-acetyl)β-cyclodextrin
Chirality, 1997Co-Authors: Ulrike Holzgrabe, Henning Mallwitz, S. K. Branch, T.m. Jefferies, Michael WieseAbstract:NMR spectroxcopy has been used to compare the interaction of ephedrine and N-Methylephedrine with β-cyclodextrin, heptakis(2,3-di-O-acetyl)β-cyclodextrin, heptakis(6-O-acetyl)β-cyclodextrin. The stoichiometry of the complexes formed between all three cyclodextrins and N-Methylephedrine was found to be 1:1 by UV spectroscopy by means of the Job technique. NMR spectra of the single enantiomers of ephedrine and N-Methylephedrine in the presence of all three cyclodextrins gave information about the parts of the ligands which interact differently with the host molecules and may be responsible for the chiral discrimination. To quantify the complex stabilities, binding constants were calculated from the changes in the chemical shifts of the ligand signals upon complexation. Analyses of the coupling constants of both species showed that no significant conformational change occurs upon complexation. ROESY spectra of these optical isomers with all three cyclodextrins provided detailed information about the geometry of the complexes. Different intermolecular cross-peaks between the individual isomers of ephedrine and N-Methylephedrine were found for native β-cyclodextrin and its 2,3-diacetylated derivative but not for 6-acetyl cyclodextrin. Analyses of the intramolecular cross-signals of the ligands confirmed that no significant conformational change occurs upon complexation. Chirality 9:211–219, 1997. © 1997 Wiley-Liss, Inc.