Gas Chromatographic Enantiomer Separation with Modified Cyclodextrins
Author: Wilfried A. König
Publisher:
Published: 1992
Total Pages: 184
ISBN-13:
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Author: Wilfried A. König
Publisher:
Published: 1992
Total Pages: 184
ISBN-13:
DOWNLOAD EBOOKAuthor: Wolfgang König
Publisher: Wiley-VCH
Published: 1999-01-06
Total Pages: 152
ISBN-13: 9783527297122
DOWNLOAD EBOOKAuthor: Weihua Tang
Publisher: Springer Science & Business Media
Published: 2013-05-24
Total Pages: 266
ISBN-13: 3642376487
DOWNLOAD EBOOKModified Cyclodextrins for Chiral Separation offers a review of the latest advances in developing modified cyclodextrins as chiral selectors for various chromatographic and electromigration techniques. Over the years, many descriptions of chiral separation have appeared in academic journals and books, but most of them have been devoted to either the development of analytical methods and protocols or the summary of different chiral selectors, including cyclodextrins for chiral separation applications. This is in marked contrast to this volume which focuses on the research endeavors concerning the development of cyclodextrin derivatives specifically as either chiral mobile phases for capillary electrophoresis, or chiral stationary phases for various chromatographic techniques including gas chromatography, or high-performance liquid chromatography and supercritical fluid chromatography. The ongoing thread in this book is the synthesis of structurally-defined cyclodextrin derivatives and their applications in enantiomer separation by means of different analytical techniques. Modified Cyclodextrins for Chiral Separation is intended for those who are interested in expanding their knowledge of cyclodextrin chemistry and chiral separation, and in what cyclodextrin modification can be made to suit the needs of chiral selectors for different analytical techniques. It primarily focuses on the state-of-the-art cyclodextrin chemistry which is the basis for all chiral selectors used in these chiral separation techniques. Weihua Tang, PhD, is a professor at the Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Nanjing University of Science and Technology, China. Siu-Choon Ng, PhD, is a professor at the Division of Chemical and Biomedical Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore. Dongping Sun, PhD, is a professor at the Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Nanjing University of Science and Technology, China.
Author:
Publisher:
Published: 2002
Total Pages:
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DOWNLOAD EBOOKCyclodextrin (CD) derivatives are widely used as chiral stationary phases in capillary gas chromatography. Their performance depends substantially on the side chains attached to the hydroxyl groups of the glucose moieties. In this study new classes of CD-derivatives suitable for gas chromatographic (GC) separation of enantiomers were synthesized by introducing (i) acetal functions and (ii) chiral acyl moieties at positions 2 and 3 of the glucose units. Octakis(2,3-di-O-methoxymethyl-6-O-tert-butyldimethylsilyl)-g-cyclodextrin (2,3- MOM-6-TBDMS-g-CD) obtained by reaction of 6-O-TBDMS-g-cyclodextrin with methoxymethylchloride (MOM-Cl) was synthesized as first representative of cyclodextrin GC stationary phases containing alkoxymethyl side chains. The structure was confirmed by NMR and mass spectrometry. The suitability of the material diluted in polysiloxane as GC stationary phase was shown. Enantioseparations could be achieved for a broad spectrum of chiral volatiles from various chemical classes. Structural influences of the analytes on the enantiodifferentiations were demonstrated. High separation factors were observed for the hydroxyketone acetoin (a = 1.8) and some methyl branched ketones. Pronounced enantioseparations were also determined for cyclic pentenolone and furanone derivatives. To investigate the impact of the size of the CD torus, the 2,3-MOM-derivatives of the b- and a-CD analogs were synthesized. The spectrum of compounds for which enantiomers could be separated on 2,3-MOM-6-TBDMS-b-CD was more limited and the enantioseparations achieved were generally less pronounced compared to the g-CD derivative. However, for 2-alkyl esters unusually high separation factors (a up to 4.31) were observed. Using 2-pentyl acetate as example, phenomena underlying the enantioseparation were investigated by determining thermodynamic parameters. The data showed that only one enantiomer is retained significantly on the chiral stationary phase whereas the other one behaves.
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DOWNLOAD EBOOKAuthor: Adel Khalil Mish'al
Publisher:
Published: 1997
Total Pages: 366
ISBN-13:
DOWNLOAD EBOOKAuthor: Adel Khalil Abdulla Mish'al
Publisher:
Published: 1997
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAuthor: Eisuke Takahisa
Publisher:
Published: 2005
Total Pages: 230
ISBN-13:
DOWNLOAD EBOOKAuthor: Sheree N. Allen
Publisher:
Published: 2010
Total Pages:
ISBN-13:
DOWNLOAD EBOOKSince biological processes depend on the stereospecific creation and conversion of chiral molecules, each enantiomer of a molecule can have a different biological effect. While numerous synthetic drugs are sold in racemic form for reasons of cost and convenience, in many cases one of the two enantiomers of a drug will cause undesirable and perhaps even devastating effects. Therefore, effective methods for the separation and quantification of enantiomers are of great importance. Enantiomers can be separated only with the use of systems containing an optically active chiral selector. Modified cyclodextrins (CDs) are widely used as chiral selectors by virtue of their ability to form inclusion complexes. Because of the remarkably high efficiency, and sensitivity of chiral gas chromatography (GC), chiral separations by this method represent a preferred method for enantiomer analysis. The basic property of CDs that allows them to be successful for enantiomer separations is their ability to form selective inclusion complexes with a wide variety of organic molecules. The preparation and application of modified cyclodextrins for the GC separation of enantiomers is a focal point of this research. In effort to identify useful new derivatives, modifications involving unique and separate reaction of the secondary hydroxyl groups and/or annulations bridging the secondary oxygens have been examined. Several new cyclodextrin derivatives, e.g. per(6-OTBS-2,3-O-diformyl)-[beta]-CD, per(6-OTBS-2,3-O-cyclodimethylsilyl)-[beta]-CD, per(6-deoxy-2,3-O-cyclodimethylsilyl)-[beta]-CD and a mixed formyl/acetyl phase have been synthesized and evaluated as components of stationary phases for capillary GC. The efficiency of each new phase to separate enantiomers was evaluated against a 30 analyte panel to evaluate the influence of the different substituents on the selectivity. These enantioseparations were also compared to those observed on four commercially available chiral phases using the same 30 analyte panel. Overall, this work resulted in nine new CD derivatives and the discovery of a new chiral selector that is comparable in efficiency to what is currently commercially available.
Author: Volker Schurig
Publisher: Springer
Published: 2013-12-16
Total Pages: 286
ISBN-13: 3319032399
DOWNLOAD EBOOKThe series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.