101
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Wu X, Gao H, Lin B. STUDY OF THE ENZYMATIC ISOMERIZATION OF GLUCOSE DURING REVERSE-PHASE LIQUID CHROMATOGRAPHY. CHEM ENG COMMUN 2010. [DOI: 10.1080/00986440903574826] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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102
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Trapp O, Sahraoui L, Hofstadt W, Könen W. The stereodynamics of 1,2-dipropyldiaziridines. Chirality 2010; 22:284-91. [PMID: 19496154 DOI: 10.1002/chir.20742] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
N-alkylated trans-diaziridines are an intriguing class of compounds with two stereogenic nitrogen atoms which easily interconvert. In the course of our investigations of the nature of the interconversion process via nitrogen inversion or electrocyclic ring opening ring closure, we synthesized and characterized the three constitutionally isomeric diaziridines 1,2-di-n-propyldiaziridine 1, 1-isopropyl-2-n-propyldiaziridine 2, and 1,2-diisopropyldiaziridine 3 to study the influence of the substituents on the interconversion barriers. Enantiomer separation was achieved by enantioselective gas chromatography on the chiral stationary phase Chirasil-beta-Dex with high separation factors alpha (1-isopropyl-2-n-propyldiaziridine: 1.18; 1, 2-diisopropyldiaziridine: 1.24; 100 degrees C 50 kPa He) for the isopropyl substituted diaziridines. These compounds showed pronounced plateau formation between 100 and 150 degrees C, and peak coalescence at elevated temperatures. The enantiomerization barriers DeltaG(double dagger) and activation parameters DeltaH(double dagger) and DeltaS(double dagger) were determined by enantioselective dynamic gas chromatography (DGC) and direct evaluation of the elution profiles using the unified equation implemented in the software DCXplorer. Interestingly, 1-isopropyl-2-n-propyldiaziridine and 1,2-diisopropyldiaziridine exhibit similar high interconversion barriers DeltaG(double dagger) (100 degrees C) of 128.3 +/- 0.4 kJ mol(-1) and 129.8 +/- 0.4 kJ mol(-1), respectively, which indicates that two sterically demanding substituents do not substantially increase the barrier as expected for a distinct nitrogen inversion process.
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Affiliation(s)
- Oliver Trapp
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany.
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103
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Integration of reaction and separation in a micro-capillary column reactor—Palladium nanoparticle catalyzed C–C bond forming reactions. Chem Eng Sci 2010. [DOI: 10.1016/j.ces.2009.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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104
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Cannazza G, Carrozzo MM, Battisti U, Braghiroli D, Parenti C, Troisi A, Troisi L. Determination of kinetic parameters of enantiomerization of benzothiadiazines by DCXplorer. Chirality 2010; 22:789-97. [DOI: 10.1002/chir.20838] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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105
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Piron F, Vanthuyne N, Joulin B, Naubron JV, Cismaş C, Terec A, Varga RA, Roussel C, Roncali J, Grosu I. Synthesis, structural analysis, and chiral investigations of some atropisomers with EE-tetrahalogeno-1,3-butadiene core. J Org Chem 2010; 74:9062-70. [PMID: 19886632 DOI: 10.1021/jo901762j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The atropenantiomers of stable 1,2,3,4-tetrahalo-1,3-butadiene derivatives (where halogeno stands for bromine or iodine) were separated with use of chiral HPLC. The barriers for the enantiomerization process were determined on-line by dynamic HPLC (DHPLC) or off-line by classical kinetic measurements. In the case of the tetrachloro compound, the barrier was too low for DHPLC and its value was obtained by dynamic NMR experiments. The obtained barriers for chloro, bromo, and iodo derivatives correlate with the van der Waals radii of the halogens. The absolute configuration of the isolated enantiomers of the tetraiodo and tetrabromo compounds was assigned by comparison of the experimental and conformations averaged calculated VCD spectra. The identification of a signature band of the absolute configuration of the butadiene core, the sign and location of which are independent from the different conformations and substituents, allowing the safe assignment of the absolute configuration of the enantiomers of chiral 1,3-butadienes, is also reported.
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Affiliation(s)
- Flavia Piron
- Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Cluj-Napoca, 11 Arany Janos str., 400028, Cluj-Napoca, Romania
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106
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Stereodynamic investigation of labile stereogenic centres in dihydroartemisinin. Molecules 2010; 15:1309-23. [PMID: 20335983 PMCID: PMC6257325 DOI: 10.3390/molecules15031309] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2010] [Revised: 01/25/2010] [Accepted: 03/04/2010] [Indexed: 11/16/2022] Open
Abstract
Since its identification in the early 1970s, artemisinin, as well as semi-synthetic derivatives and synthetic trioxanes, have been used in malaria therapy. Reduction of artemisinin by NaBH4 produced dihydroartemisinin (DHA), and yielded a new stereochemically labile centre at C-10, which, in turn, provided two interconverting lactol hemiacetal epimers (namely alpha and beta), whose rate of interconversion depends on buffer, pH, and solvent polarity. Since interconversion of the two epimers occurred on a chromatographic time-scale, this prompted a thorough investigation of the phenomenon as a crucial requisite of any analytical method aimed at quantitating this family of drugs. In this critical review we discuss the current importance of the on-column epimerization of DHA in the development of analytical methods aimed at quantifying the drug, with the purpose of identifying the optimal conditions to minimize on-column epimerization while achieving the best selectivity and efficiency of the overall separation.
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107
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Trapp O. Investigation of the stereodynamics of molecules and catalyzed reactions by CE. Electrophoresis 2010; 31:786-813. [DOI: 10.1002/elps.200900599] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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108
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Chromatographic peak deconvolution of constitutional isomers by multiple-reaction-monitoring mass spectrometry. J Chromatogr A 2010; 1217:1010-6. [DOI: 10.1016/j.chroma.2009.09.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 09/11/2009] [Accepted: 09/17/2009] [Indexed: 11/21/2022]
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109
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On- and off column enantiomerization of 4,4′-bisquinolin-2-ones: A comparison of Auto-, DHPLcy2k and DCXplorer calculated thermodynamic data generated by dynamic high, performance liquid chromatography with theoretically calculated data. J Chromatogr A 2010; 1217:1017-23. [DOI: 10.1016/j.chroma.2009.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 11/27/2009] [Accepted: 12/01/2009] [Indexed: 11/21/2022]
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110
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Chifuntwe C, Zhu F, Huegel H, Marriott PJ. Dynamic interconversion of chiral oxime compounds in gas chromatography. J Chromatogr A 2010; 1217:1114-25. [DOI: 10.1016/j.chroma.2009.11.084] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 11/23/2009] [Accepted: 11/25/2009] [Indexed: 12/01/2022]
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111
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Pasti L, Cavazzini A, Nassi M, Dondi F. Dynamic chromatography: A stochastic approach. J Chromatogr A 2010; 1217:1000-9. [DOI: 10.1016/j.chroma.2009.10.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 10/05/2009] [Accepted: 10/12/2009] [Indexed: 10/20/2022]
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112
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Wu E, Jung SH, Chen J, Kim YH, Park KL, Lee W, Kang JS. Racemization of 6-methoxydihydrosanguinarine in methanol investigated by enantioselective dynamic HPLC. J Pharm Biomed Anal 2010; 51:103-6. [DOI: 10.1016/j.jpba.2009.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/04/2009] [Accepted: 08/10/2009] [Indexed: 10/20/2022]
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113
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Lin CE, Ko TC, Kuo CM, Trapp O, Lin WY, Lin CH, Wu JC, Liu YC. Determination of enantiomerization barrier of thioridazine by dynamic capillary electrophoresis using sulfated cyclodextrins as chiral selectors. Electrophoresis 2009; 30:3071-3078. [DOI: 10.1002/elps.200900160] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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114
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Iki N, Takahashi M, Takahashi T, Hoshino H. Ligand-Substitution Mode Capillary Electrophoretic Reactor: Extending Capillary Electrophoretic Reactor toward Measurement of Slow Dissociation Kinetics with a Half-Life of Hours. Anal Chem 2009; 81:7849-54. [DOI: 10.1021/ac901296j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Nobuhiko Iki
- Laboratory of Environmental Analytical Chemistry, Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Mariko Takahashi
- Laboratory of Environmental Analytical Chemistry, Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Toru Takahashi
- Laboratory of Environmental Analytical Chemistry, Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Hitoshi Hoshino
- Laboratory of Environmental Analytical Chemistry, Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan
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115
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Accessing reaction rate constants in on-column reaction chromatography: an extended unified equation for reaction educts and products with different response factors. Anal Bioanal Chem 2009; 395:1673-9. [DOI: 10.1007/s00216-009-2993-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/22/2009] [Accepted: 07/17/2009] [Indexed: 11/26/2022]
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116
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Teutenberg T. Potential of high temperature liquid chromatography for the improvement of separation efficiency—A review. Anal Chim Acta 2009; 643:1-12. [DOI: 10.1016/j.aca.2009.04.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 04/01/2009] [Accepted: 04/03/2009] [Indexed: 10/20/2022]
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117
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Cirilli R, Costi R, Di Santo R, La Torre F, Pierini M, Siani G. Perturbing Effects of Chiral Stationary Phase on Enantiomerization Second-Order Rate Constants Determined by Enantioselective Dynamic High-Performance Liquid Chromatography: A Practical Tool to Quantify the Accessible Acid and Basic Catalytic Sites Bonded on Chromatographic Supports. Anal Chem 2009; 81:3560-70. [DOI: 10.1021/ac802212s] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roberto Cirilli
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy, Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, I-00185 Rome, Italy, and Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio”, via dei Vestini 31-66013 Chieti, Italy
| | - Roberta Costi
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy, Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, I-00185 Rome, Italy, and Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio”, via dei Vestini 31-66013 Chieti, Italy
| | - Roberto Di Santo
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy, Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, I-00185 Rome, Italy, and Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio”, via dei Vestini 31-66013 Chieti, Italy
| | - Francesco La Torre
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy, Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, I-00185 Rome, Italy, and Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio”, via dei Vestini 31-66013 Chieti, Italy
| | - Marco Pierini
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy, Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, I-00185 Rome, Italy, and Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio”, via dei Vestini 31-66013 Chieti, Italy
| | - Gabriella Siani
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy, Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale A. Moro 5, I-00185 Rome, Italy, and Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio”, via dei Vestini 31-66013 Chieti, Italy
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118
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Evenhuis CJ, Haddad PR. Joule heating effects and the experimental determination of temperature during CE. Electrophoresis 2009; 30:897-909. [DOI: 10.1002/elps.200800643] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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119
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Carrozzo MM, Cannazza G, Battisti U, Braghiroli D, Parenti C. Simultaneous determination of enantiomerization and hydrolysis kinetic parameters of chiralN-alkylbenzothiadiazine derivatives. Chirality 2009; 22:389-97. [DOI: 10.1002/chir.20751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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120
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Bremer S, Trapp O. Investigation of the stereodynamics of tris-(α-diimine)-transition metal complexes by enantioselective dynamic MEKC. Electrophoresis 2009; 30:329-36. [DOI: 10.1002/elps.200800320] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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121
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Schurig V. Elaborate treatment of retention in chemoselective chromatography--the retention increment approach and non-linear effects. J Chromatogr A 2008; 1216:1723-36. [PMID: 19070865 DOI: 10.1016/j.chroma.2008.11.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 11/07/2008] [Accepted: 11/10/2008] [Indexed: 11/27/2022]
Abstract
The retention increment approach is described which quantifies the association equilibria of a selectand and a selector in complexation and inclusion chromatography. A thermodynamic treatment of enantioselectivity based on retention phenomena in chromatography including entropy/enthalpy compensation and the isoenantioselective temperature is advanced. Kinetic parameters of enantiomerization are discussed. Non-linear effects, both existent and elusive, are described and proposed, respectively. The enantioselectivity pertaining to catalysis vs. chromatography is compared and a unified nomenclature is proposed. Through an educational effort, this account is aimed at providing a deeper insight into chemoselective aspects of chromatography thereby stimulating further research of both established and speculative phenomena of the most intriguing manifestation of chemoselectivity, that is, of enantioselectivity.
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Affiliation(s)
- Volker Schurig
- Institute of Organic Chemistry, University of Tübingen, 72076 Tübingen, Germany.
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122
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Cannazza G, Carrozzo MM, Braghiroli D, Parenti C. Enantiomerization and hydrolysis of (±)-7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide by stopped-flow multidimensional high-performance liquid chromatography. J Chromatogr A 2008; 1212:41-7. [DOI: 10.1016/j.chroma.2008.09.087] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 09/25/2008] [Accepted: 09/26/2008] [Indexed: 11/27/2022]
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123
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Ciogli A, Dalla Cort A, Gasparrini F, Lunazzi L, Mandolini L, Mazzanti A, Pasquini C, Pierini M, Schiaffino L, Mihan FY. Enantiomerization of Chiral Uranyl−Salophen Complexes via Unprecedented Ligand Hemilability: Toward Configurationally Stable Derivatives. J Org Chem 2008; 73:6108-18. [DOI: 10.1021/jo800610f] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alessia Ciogli
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Antonella Dalla Cort
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Francesco Gasparrini
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Lodovico Lunazzi
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Luigi Mandolini
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Andrea Mazzanti
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Chiara Pasquini
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Marco Pierini
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Luca Schiaffino
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
| | - Francesco Yafteh Mihan
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 Roma 62, 00185 Roma, Italy, Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Chimica Organica “A Mangini”, Università di Bologna, Viale Risorgimento 4, 40136 Bologna
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124
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Skrdla PJ, Bopra A, Chasse T, Wang T. A high-temperature liquid chromatographic reactor approach for investigating the solvolytic stability of a pharmaceutical compound and an investigation of its retention behavior on a C18-modified zirconia stationary phase. J Pharm Biomed Anal 2008; 47:312-9. [DOI: 10.1016/j.jpba.2008.01.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 01/10/2008] [Accepted: 01/13/2008] [Indexed: 11/26/2022]
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125
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Gas chromatographic high-throughput screening techniques in catalysis. J Chromatogr A 2007; 1184:160-90. [PMID: 18035362 DOI: 10.1016/j.chroma.2007.10.086] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 10/09/2007] [Accepted: 10/29/2007] [Indexed: 11/23/2022]
Abstract
Discovering highly efficient catalysts is of great scientific and economical interest. Advances in high-throughput assays in combination with sophisticated analytical techniques have increased the rapidity with which catalysts can be identified and optimized. Understanding how kinetics in the mechanism of catalysis is controlled by structural parameters is essential for a directed design of catalysts. To identify such rate-controlling elementary steps and to develop and refine models, comprehensive experimental kinetic data of a broad variety of substrates are necessary. In the present article concepts of high-throughput screening techniques in catalysis using gas chromatography are reviewed in a survey covering the period from 1998 to 2007. To cover also the origins of concepts and groundbreaking experiments in this research area milestones going back to 1950 are also reviewed. The first part of the review will focus on off-line gas chromatographic analysis, the second part on on-line gas chromatographic analysis covering sequential, parallelized and high-throughput multiplexing gas chromatography. The third part presents recent advances in the integration of chemical transformation and analysis in gas chromatography. The present review article describes the state-of-the-art, scope and limitations, and applications of these different high-throughput screening approaches.
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126
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Trapp O, Weber SK, Bauch S, Hofstadt W. High-Throughput Screening of Catalysts by Combining Reaction and Analysis. Angew Chem Int Ed Engl 2007; 46:7307-10. [PMID: 17668428 DOI: 10.1002/anie.200701326] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Oliver Trapp
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
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127
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Trapp O, Weber S, Bauch S, Hofstadt W. Hochdurchsatz-Screening von Katalysatoren durch Integration von Reaktion und Analyse. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200701326] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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128
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Kanatyeva AY. Chromatographic elution profile of an analyte involved in reversible chemical reaction of the type A+B↔AB. J Chromatogr A 2007; 1150:112-6. [PMID: 16965781 DOI: 10.1016/j.chroma.2006.08.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 08/16/2006] [Accepted: 08/21/2006] [Indexed: 11/18/2022]
Abstract
The chromatographic peak profile of the analyte involved in a chemical reaction of the type A + B <--> AB is considered using method of the apparent adsorption isotherm. The apparent isotherms derived are nonlinear even under assumption of Henry isotherms of individual solutes. Nonlinearity of apparent adsorption isotherm results in peak distortion. The resulted chromatographic peak profile depends on several factors such as the equilibrium constant K(mob) and Henry constants of the solutes. Simulated peak profiles of solutes involved in the chemical reaction are presented as illustration of influence of various factors.
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Affiliation(s)
- A Yu Kanatyeva
- Topchiev Institute of Petrochemical Synthesis RAS, 119991 Moscow, Lenin av. 29, Russia.
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129
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Trapp O. A dynamic molecular probe to investigate catalytic effects and Joule heating in enantioselective MEKC. Electrophoresis 2007; 28:691-6. [PMID: 17226759 DOI: 10.1002/elps.200600596] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Enantiomerization of ferroin [tris(1,10-phenanthroline)-iron(II)-complex] was investigated by enantioselective dynamic micellar EKC. The enantiomer separation was performed in an aqueous 50 mM sodium borate/sodium dihydrogenphosphate buffer at pH 8.0 in the presence of the chiral surfactant sodium cholate. The unified equation of dynamic chromatography was employed to determine reaction rate constants from the electropherograms featured with distinct plateau formation. Activation parameters DeltaH( not equal) = 124.0 +/- 0.5 kJ/mol and DeltaS( not equal) = 121 +/- 1 J.K(-1)mol(-1) were calculated from temperature-dependent measurements between 10.0 and 27.5 degrees C in 2.5 K steps. Considering the data obtained by polarimetry of enantiomeric pure ferroin in water, it was found that enantiomerization rate in the micelle is accelerated by a factor of 12. Because of the highly positive activation entropy DeltaS( not equal), ferroin was used as a temperature-sensitive dynamic molecular probe to determine temperature deviations caused by Joule heating.
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Affiliation(s)
- Oliver Trapp
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
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130
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Ali Rizvi SA, Zheng J, Apkarian RP, Dublin SN, Shamsi SA. Polymeric sulfated amino acid surfactants: a class of versatile chiral selectors for micellar electrokinetic chromatography (MEKC) and MEKC-MS. Anal Chem 2007; 79:879-98. [PMID: 17263313 PMCID: PMC2569972 DOI: 10.1021/ac061228t] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, three amino acid-derived (l-leucinol, l-isoleucinol, l-valinol) sulfated chiral surfactants are synthesized and polymerized. These chiral sulfated surfactants are thoroughly characterized to determine critical micelle concentration, aggregation number, polarity, optical rotation, and partial specific volume. For the first time the morphological behavior of polymeric sulfated surfactants is revealed using cryogenic high-resolution electron microscopy. The polysodium N-undecenoyl-l-leucine sulfate shows distinct tubular structure, while polysodium N-undecenoyl-l-valine sulfate also shows tubular morphology but without any distinct order of the tubes. On the other hand, polysodium N-undecenoyl-l-isoleucine sulfate (poly-l-SUCILS) displays random distribution of coiled/curved filaments with heavy association of tightly and loosely bound water. All three polymeric sulfated surfactants are compared for enantioseparation of a broad range of structurally diverse racemic compounds at very acidic, neutral, and basic pH conditions in micellar electrokinetic chromatography (MEKC). A small combinatorial library of 10 structurally related phenylethylamines (PEAs) is investigated for chiral separation under acidic and moderately acidic to neutral pH conditions using an experimental design. In contrast to neutral pH conditions, at acidic pH, significantly enhanced chiral resolution is obtained for class I and class II PEAs due to the compact structure of polymeric sulfated surfactants. It is observed that the presence of a hydroxy group on the benzene ring of PEAs resulted in deterioration of enantioseparation. A sensitive MEKC-mass spectrometry (MS) method is developed for one of the PEAs (e.g., (+/-)-pseudoephedrine) in human urine. Very low limit of detection (LOD) is obtained at pH 2.0 (LOD 325 ng/mL), which is approximately 16 times better compared to pH 8.0 (LOD 5.2 microg/mL). Another broad range of chiral analytes (beta-blockers, phenoxypropionic acid, benzoin derivatives, PTH-amino acids, benzodiazepinones) studied also provided improved chiral separation at low pH compared to high-pH conditions. Among the three polymeric sulfated surfactants, poly-l-SUCILS with two chiral centers on the polymer head group provided overall higher enantioresolution for the investigated acidic, basic, and neutral compounds. This work clearly demonstrates for the first time the superiority of chiral separation and sensitive MS detection at low pH over conventional high-pH chiral separation and detection employing anionic chiral polymeric surfactants in MEKC and MEKC-MS.
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Affiliation(s)
- Syed Asad Ali Rizvi
- Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA, 30303, USA
| | - Jie Zheng
- Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA, 30303, USA
| | - Robert P. Apkarian
- Integrated Microscopy and Microanalytical Facility, Emory University, 1515 Pierce Drive, Atlanta, Georgia 30322, USA
| | - Steven N. Dublin
- Integrated Microscopy and Microanalytical Facility, Emory University, 1515 Pierce Drive, Atlanta, Georgia 30322, USA
| | - Shahab A. Shamsi
- Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA, 30303, USA
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131
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Skelley AM, Mathies RA. Rapid on-column analysis of glucosamine and its mutarotation by microchip capillary electrophoresis. J Chromatogr A 2006; 1132:304-9. [PMID: 16919655 DOI: 10.1016/j.chroma.2006.07.082] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 07/25/2006] [Accepted: 07/28/2006] [Indexed: 11/29/2022]
Abstract
A novel electrophoretic microchip method for analyzing alpha- and beta-d-glucosamine and their interconversion in solution is presented. d-Glucosamine is labeled with fluorescamine and analyzed by capillary electrophoresis in under 2 min revealing its pH-dependent mutarotation between the alpha- and beta-anomers. The forward interconversion rates for the labeled sugars, based on an iterative analysis of the plateau heights between the peaks, are 0.72+/-0.09, 1.3+/-0.1, and 2.2+/-0.3 x 10(-3)s(-1) at pH 8.99, 9.51 and 10.01, respectively. In a separate experiment, the mutarotation of the unlabeled alpha-d-anomer was followed; the relative intensities of the alpha- and beta-peaks as a function of reaction time at pH 9.51 give a forward rate constant of 0.6+/-0.1 x 10(-3)s(-1). These results demonstrate that fast microchip separations, previously exploited for amine, amino acid, and nucleobase analysis, can also be used to analyze amino sugars and their mutarotation.
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Affiliation(s)
- Alison M Skelley
- Department of Chemistry, University of California, MS 1460, Berkeley, CA 94720, USA
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132
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Lenev DA, Lyssenko KA, Golovanov DG, Buss V, Kostyanovsky RG. Bis-ortho-Substitution by Methyl Groups Dramatically Increases the Racemization Barrier of Tröger Bases. Chemistry 2006; 12:6412-8. [PMID: 16729337 DOI: 10.1002/chem.200501532] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have shown through racemization kinetics studies that the enantiomerization barriers of the bis-ortho-methyl substituted Tröger bases 2 and 3 in acidic media are raised by 30 kJ mol(-1) relative to the parent compound 1, that is 130.4(4) and 131.6(4) kJ mol(-1), respectively (105 degrees C, pH 1, ethylene glycol). The enantiomerization barrier of para-methoxy-para-nitro substituted Tröger base 4 was determined by dynamic capillary electrophoresis to 96.3(2) kJ mol(-1) (25 degrees C, pH 2.2, H(2)O), which is lower by 5 kJ mol(-1) relative to 1. The influence of deutero-substitution on the racemization rates was also studied. The influence of steric and electronic factors on the enantiomerization barrier was investigated by quantum-mechanical (DFT) calculations. It is shown that enantiomerization takes place in two steps: ring-opening and further interconversion of the monocyclic intermediate. For the interconversion to occur a transition state has to be passed which is sensitive to steric effects. Ortho-substitution by methyl groups significantly increases the energy of this state. Thus, compounds 2 and 3 are the simplest Tröger bases which are configurationally stable in acidic media.
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Affiliation(s)
- Denis A Lenev
- Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 ul. Kosygina, 119991 Moscow, Russia.
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133
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Trapp O. The unified equation for the evaluation of degenerated first-order reactions in dynamic electrophoresis. Electrophoresis 2006; 27:2999-3006. [PMID: 16800031 DOI: 10.1002/elps.200500907] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An analytical solution for the unified equation for degenerated (pseudo-) first-order reactions, e.g., enantiomerization processes, in dynamic CE is presented, and validated with a dataset of 31 250 elution profiles covering typical experimental parameters. The unified equation was applied to determine the enantiomerization barrier of the hypnotic glutarimide derivative thalidomide (Contergan(R)) by dynamic capillary electrokinetic chromatography (DEKC). The enantiomer separation of thalidomide was performed in an aqueous 50 mM sodium borate buffer at pH 9.3 in the presence of the chiral mobile phase additive carboxymethyl-beta-CD. Interconversion profiles featuring pronounced plateau formation were observed. Activation parameters DeltaH( not equal) and DeltaS( not equal) were obtained from temperature-dependent measurements between 20.0 and 37.5 degrees C in 2.5K steps. From the activation parameters the enantiomerization barrier of thalidomide at 37 degrees C under basic conditions were calculated to be DeltaG( not equal) = 93.2 kJ/mol. Comparison of the kinetic data with results obtained at pH 8.0 reveals the catalytic influence of the base on the enantiomerization barrier.
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Affiliation(s)
- Oliver Trapp
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.
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134
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D'Acquarica I, Gasparrini F, Pierini M, Villani C, Zappia G. Dynamic HPLC on chiral stationary phases: A powerful tool for the investigation of stereomutation processes. J Sep Sci 2006; 29:1508-16. [PMID: 16894796 DOI: 10.1002/jssc.200600129] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Dynamic HPLC on enantioselective stationary phases has become a well-established technique to investigate chiral molecules with internal motions that result in stereoinversion and occur on the time scale of the separation process. Kinetic parameters for the on-column interconversion phenomena can be extracted from experimental peak profiles by computer simulation or by direct calculation methods. The technique has been used in a wide range of temperatures and is complementary in scope to dynamic NMR spectroscopy.
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Affiliation(s)
- Ilaria D'Acquarica
- Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università degli Studi di Roma La Sapienza, Rome, Italy
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135
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Heegaard NHH, Jørgensen TJD, Cheng L, Schou C, Nissen MH, Trapp O. Interconverting Conformations of Variants of the Human Amyloidogenic Protein β2-Microglobulin Quantitatively Characterized by Dynamic Capillary Electrophoresis and Computer Simulation. Anal Chem 2006; 78:3667-73. [PMID: 16737222 DOI: 10.1021/ac060194m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Capillary electrophoretic separation profiles of cleaved variants of beta2-microglobulin (beta2m) reflect the conformational equilibria existing in solutions of these proteins. The characterization of these equilibria is of interest since beta2m is responsible for amyloid formation in dialysis-related amyloidosis and thus is able to attain alternative conformations that lead to irreversible aggregation and precipitation. In this study, we quantitate the increased conformational instability of cleaved beta2m by extracting rate constants and activation energies by simulating the experimental data using a unified theory for dynamic chromatography and dynamic electrophoresis. The results are correlated with the outcome of independent experiments based on mass spectrometric measurement of H/D exchange. This study illustrates that dynamic capillary electrophoresis is suitable for the investigation of the interconversion of protein conformations of amyloidogenic molecules and is not only restricted to ideal model compounds.
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136
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Trapp O. The unified equation for the evaluation of first order reactions in dynamic electrophoresis. Electrophoresis 2006; 27:534-41. [PMID: 16380957 DOI: 10.1002/elps.200500708] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The unified equation was validated for first order reactions in dynamic CE with a data set of 31 250 elution profiles. Comparison with the results from conventional iterative computer simulation revealed that the unified equation is superior in terms of success rate and precision. The unified equation was applied to determine the cis-trans isomerization rate constants of the angiotensin converting enzyme inhibitor captopril. The separation of the rotational cis-trans isomeric drug has been performed in an aqueous 66 mM citric acid/Tris buffer at pH 3.0 in a 50 cm polyacrylamide-coated fused-silica capillary. Interconversion profiles featuring pronounced plateau formation and peak broadening were observed. Activation parameters DeltaH not equal and DeltaS not equal were obtained from temperature-dependent measurements between 10 and 25 degrees C in 2.5 K steps. From the activation parameters the isomerization barriers of captopril at 37 degrees C under acidic conditions were calculated to be DeltaG not equal trans-->cis=90.6 kJ/mol and DeltaG not equal cis-->trans=84.6 kJ/mol. By comparison of the kinetic data with the results obtained under basic conditions (pH 9.3) a mechanism of isomerization could be proposed.
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Affiliation(s)
- Oliver Trapp
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
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137
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Trapp O. Fast and precise access to enantiomerization rate constants in dynamic chromatography. Chirality 2006; 18:489-97. [PMID: 16642493 DOI: 10.1002/chir.20276] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An analytical solution of the unified equation to evaluate elution profiles of interconverting enantiomers in dynamic chromatography is presented. Rate constants k1 and k(-1) and Gibbs activation energies are directly obtained from the chromatographic parameters (retention times tR A and tR A of the interconverting enantiomers, the peak widths at half height wA and wB, and the relative plateau height hp), and the initial amounts A0 and B0 of the enantiomers without any iterative and time consuming computational step. Therefore, this equation is no longer limited to racemic analytes. The analytical solution presented here was validated by comparison with a dataset of 125,000 simulated elution profiles of enantiomerizations. Furthermore, it was found that the recovery rate from a defined dataset is on average 40% higher using the unified equation compared to evaluation methods based on iterative computer simulation. The new equation was applied to determine the enantiomerization rate constant of 1-n-butyl-2-tert-butyldiaziridine by enantioselective gas chromatography. The activation parameters (DeltaH(double dagger) = 112.6 +/- 2.5 kJ/mol and DeltaS(double dagger) = -27 +/- 2 J/(K mol) were obtained from temperature-dependent measurements between 100 degrees C and 140 degrees C in 10K steps.
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Affiliation(s)
- O Trapp
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
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