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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 1188-1197 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of Chromatographic Resolutions of Racemates, IV. Separation Efficiency of Optically Active poly [N-((S)-1-phenylethyl)acrylamide] Depending on the Polymerisation ProcedureThe optically active suspension polymers 2a-o were synthesized from N-[(S)-1-phenylethyl]-acrylamide [(S)-1] by systematic variation of the polymerisation procedure. These adsorbents whose separation efficiencies were determined by chromatography of racemic mandelic acid separated the enantiomers with very different results. Depending on the synthesis of 2, the optical yields were between 0(2e, f, n, o) and 43% (2i, j). Additionally, 2d separated the enantiomers of mandelamide, the optical yield being 35%. Furthermore, investigations on the particle structure of these adsorbents and the preparative partial separation of 3 are reported.
    Notes: Die optisch aktiven Suspensionspolymerisate 2a-o wurden aus N-[(S)-1-Phenyläthyl]acrylamid [(S)-1] unter systematischer Variation der Versuchsbedingungen hergestellt und auf ihre Trennwirkung durch Chromatographie racem. Mandelsäure geprüft. Die Enantiomeren wurden sehr unterschiedlich getrennt. Je nach Herstellung von 2 schwankten die optischen Ausbeuten von 0 (2e, f, n, o) bis 43% (2i, j). Bei der Trennung von racem. Mandelamid an 2d betrug sie 35%. Ferner wird über Untersuchungen zur Kornstruktur der Polymeren sowie über die präparative Anreicherung der Enantiomeren von 3 berichtet.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 237-252 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of Chromatographic Resolutions of Racemates, III. Chromatography of Racemic Mandelic Acid on Polyacrylic Esters and Amides of Optically Active Ephedrine DerivativesThe chromatographic resolution of racemic mandelic acid on optically active polyacrylic esters and amides of ephedrine derivatives was investigated using the racemate composed of specifically labelled enantiomers. Polyacryl esters of N-alkylephedrine derivatives adsorb mandelic acid, resulting in partial resolution. Evidence is presented that these polymers have affinity for mandelic acid at two points. The stereoselectivity of adsorption is determined by the configuration at C-2 of the ephedrine portion. Also, polyamides of ephedrine derivatives affect a partial resolution of mandelic acid. In contrast to the basic derivatives, the stereoselectivity is determined by the configuration at C-1. The separation efficiency of these adsorbents is highly dependent on the polymerisation procedure.
    Notes: Die chromatographische Racemattrennung von Mandelsäure an optisch aktiven Polyacryl-säureestern und -amiden von Ephedrinderivaten wurde mit 3H/14C-doppelmarkiertem Racemat untersucht. An basischen Polyacrylsäureestern von N-Alkylephedrinderivaten wird racem. Mandelsäure - wahrscheinlich über eine Zweizentrenbindung - stereoselektiv adsorbiert, wodurch eine teilweise Auftrennung in die Antipoden erfolgt. Die Stereoselektivität der Adsorption wird durch die Konfiguration an C-2 des Ephedrinteils bestimmt. Auch Polyacrylsäureamide von Ephedrinderivaten trennen racem. Mandelsäure teilweise auf, wobei die Stereoselektivität im Gegensatz zu den basischen Derivaten von der Konfiguration an C-1 bestimmt wird. Die Trennleistung der Adsorbentien hängt sehr vom Polymerisations-verfahren ab.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 778-787 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of Chromatographic Resolutions of Racemates, VII Preparative Resolutions on Optically Active PolyamidesThe optically active polyamides 1, 2a and b enable optical resolutions of racemates of α-substituted 2-phenylacetamides (3a-g), mandelic acid derivatives (4a-c), N-substituted acetamides (5a-d. 6, 7), N-acylamino acid esters (8a-h), and benzoin derivatives (9a-c). The amide 5c was resolved on a preparative scale yielding both optically pure enantiomers.
    Notes: Die optisch aktiven Polyamide 1, 2a und b trennen Racemate von α-substituierten 2-Phenylacetamiden (3a-g), Mandelsäurederivaten (4a-c), N-substituierten Acetamiden (5a-d, 6, 7), N-Acylaminosäureestern (8a-h) und Benzoinderivaten (9a-c). Das Amid 5c wurde im präparativen Maßstab in beide optisch reinen Enantiomeren aufgetrennt.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2792-2798 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of Chromatographic Resolutions of Racemates V Polymeric 1-Phenylethylamine Derivatives as Optically Active Adsorbents10 new polyacryl- and polymethacrylamides (3,5) were synthesized as crosslinked suspension polymers, starting with optically active 1-phenylethylamine derivatives. Their separation efficiencies were determined by chromatography of racemic mandelic acid and mandelamide. 3 of these adsorbents separated better than the previously described 3a, the optical yields approaching 97%. These experiments demonstrate that an almost quantitative separation of racemates can be accomplished by adsorption chromatography on optically active polymers.
    Notes: 10 neue Polyacryl-bzw. Polymethacrylamide (3 bzw. 5) optisch aktiver 1-Phenyläthylamin-Derivate wurden als vernetzte Suspensionspolymerisate hergestellt und auf ihre Trennwirkung bei der Chromatographie racem. Mandelsäure und racem. Mandelamids geprüft. 3 dieser Adsorbentien trennen besser als das früher beschriebene 3a, wobei optische Ausbeuten bis zu 97% erhalten werden. Damit kann eine fast quantitative Racemattrennung durch Adsorptionschromatographie an optisch aktiven Polymeren erreicht werden.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3611-3617 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chromatographic Resolutions of Racemates, XI. Comparison of Optically Active Polyamides and Cellulose TriacetateOn optically active polyacrylic and polymethacrylic amides (1a-e) as well as on microcrystalline cellulose triacetate (2), numerous racemates including drugs are separated at least partially, the amide 4f completely on cellulose triacetate. By repeated chromatography on the polyamide 1a, (+)- and (-)-mandelic amide (4a) and (+)-hexobarbital (9d) also were obtained optically pure.
    Notes: An optisch aktiven Polyacryl- und Polymethacrylamiden (1a-e) sowie mikrokristallinem Cellulosetriacetat (2) werden zahlreiche Racemate einschließlich von Arzneistoffen teilweise, das Amid 4f an Cellulosetriacetat vollständig getrennt. Durch wiederholte Chromatographie an Polyamid 1a wurden zusätzlich (+)- und (-)-Mandelamid (4a) sowie (+)-Hexobarbital (9d) in optisch reiner Form erhalten.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4616-4619 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation, Optical Purity and Configuration of the Enantiomers of FlecainideThe chiral antiarrhythmic drug flecainide (rac-1) was resolved by fractional crystallization of the diastereomeric salts with optically active mandelic acid. Derivatization with (+)-1-phenylethyl isocyanate and analytical separation of the diastereomers 3 by HPLC on silica gel confirmed the optical purity of the enantiomers. CD-Spectra of the N-chloro derivatives established the absolute configuration: (-)-1 is R-, (+)-1 S-configurated.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4620-4622 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Configuration of the Praziquantel EnantiomersThe levorotatory (methanol) enantiomer of the anthelminthic agent praziquantel (rac-1) is R-, the dextrorotatory S-configurated. This assignment is based upon CD-spectra of both enantiomers and additionally confirmed by conversion of (+)- and (-)-2 to the pyrazinoisoquinolines 3 of known configuration.
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1967-1975 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation of Chromatographic Resolutions of Racemates, VI. Polymeric Amino Acid Derivatives as Optically Active AdsorbensStarting with optically active amino acids, the polyacrylamides 3a-h, 5a-d and 6a, b the polymethacrylamides 8a-c and the polyacrylic ester 6f were synthesized. The separation efficiencies of these polymers were determined by chromatography of racemic mandelic acid and mandelamide, respectively. The best separations of the enantiomers of both racemates were observed on the phenylalanine derivatives 3e and 5a.
    Notes: Die Polyacrylamide 3a-h, 5a-d und 6a, b die Polymethacrylamide 8a-c und der Polyacrylsäureester 6f wurden aus optisch aktiven Aminosäurederivaten hergestellt und auf ihre Trennwirkung durch Chromatographie racem. Mandelsäure sowie racem. Mandelamids geprüft. Die beste Trennung der Enantiomeren beider Racemate wurde an den Phenylalaninderivaten 3e und 5a beobachtet.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 2732-2734 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chloroquine Enantiomers by Chromatographic Resolution and SynthesisThe chromatographic resolution of the antimalarial drug chloroquine (1) on an optically active polyamide is described. The results reveal that the optical purity of chloroquine formerly resolved with d-bromocamphorsulfonic acid was 12% only. A facile synthesis of the enantiomers via the optically active diamine 4 is given.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 370-374 
    ISSN: 0899-0042
    Keywords: (+)-chlorthalidone ; racemization ; pH profile ; influence of liposomes ; reaction kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extent of racemization of (+)-chlorthalidone as a function of pH is examined. The minimum of the log K/pH curve is pH 3. The reaction mechanism of inversion is postulated to involve a carbenium cation over the entire pH range and a ring opening reaction in the alkaline range. The influence of liposomes on the inversion rate is also studied, retardation of the racemization rate being observed with increasing liposome concentration. A model of drug distribution between liposome phase and aqueous phase based on the Nernst distribution principle is presented and reaction kinetic aspects are considered. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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