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  • Articles  (10)
  • cyclodextrin derivatives  (5)
  • Cyclodextrins  (2)
  • Polychlorinated pesticides  (2)
  • 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane  (1)
  • 1
    ISSN: 1573-1561
    Keywords: Enantiomer discrimination ; male patrolling ; odor marking ; Hymenoptera ; Apoidea ; Andrena wilkella ; bee ; EAG ; spiroacetal ; absolute configuration ; 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Diastereomers of the spiroacetal, 2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, represent main components of the cephalic secretion from males of the solitary bee,Andrena wilkella. The major compound proved to be of high enantiomeric purity, showing (2S,6R,8S) configuration. Only the naturally occurring enantiomer attracted patrolling males in the field; its antipode was behaviorally inactive and in a racemic mixture did not inhibit response. The (E,Z) diastereomers were also found to be almost inactive. EAG studies gave the same result as the behavioral tests. The biological function of the spiroacetal is discussed in view of the evolution of the mating behavior inA. wilkella.
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  • 2
    ISSN: 0899-0042
    Keywords: capillary zone electrophoresis ; axially chiral biphenyls ; energy barrier ; cyclodextrin derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new technique is presented for the investigation of the rotational energy barrier of axially chiral biphenyls, based on capillary zone electrophoresis using cyclodextrin derivatives as chiral selectors. Only minute amounts are required for the investigation of dynamic processes with energy barriers of 100-130 kJ/mol. The influence of the chiral selector on the conformational stability of atropisomers can be determined separately for each enantiomer. Additionally, segmentation of the capillary into different buffer zones allows us to exclude any influence of the chiral selector on the rotational energy barrier. © 1996 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 499-504 
    ISSN: 0899-0042
    Keywords: enantioselective capillary gas chromatography ; cyclodextrin derivatives ; stereochemistry of terpenes ; monoterpenes ; essential oils ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary gas chromatography employing the unique selectivities of specifically substituted cyclodextrins is highly suited for stereochemical investigations of terpenoid compounds. The analysis of many essential oils have shown that monoterpene derivatives regularly occur as enantiomeric mixtures. In the case of sesquiterpene hydrocarbons, liverworts (Hepaticae) and other lower organisms usually biosynthesize compounds of opposite stereochemistry as compared to higher plants and enantiomeric mixtures occur only occasionally. The investigation of diterpene hydrocarbons has so far shown no indication of the presence of both enantiomers in the same plant. Chirality 10:499-504, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Cyclodextrin derivatives ; Polychlorinated pesticides ; Polychlorinated biphenyls (PCBs) ; Pyrethroid insecticides/Allethrin ; Organophosphorus pesticides/Acephate, Malaoxon ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of the polychlorinated polycyclic xenobiotics heptachlor, cis- and trans-chlordane, cis- and trans-heptachlorepoxide, oxychlordane, and bromocyclen have been resolved by gas chromatography with selectively substituted cyclodextrins. The order of elution of these compounds and of α-hexachlorocyclohexane (α-HCH) was determined by comparison with enantiomerically enriched reference compounds obtained by preparative enantioselective gas chromatography.A separation of the eight stereoisomers of the pyrethroid insecticide allethrin into seven peaks was achieved. Both trans-diastereomers were separated into their enantiomers and the order of elution could be determined by comparison with commercially available (S)-bioallethrin and trans-bioallethrin. Also one cis-diastereomer was separated, wheras the other cis-isomer could not be resolved. In addition 15 out of 19 stable atropisomeric polychlorinated biphenyls with 5, 6 and 7 chlorine substituents, some chiral organophosphorus pesticides, including acephate and malaoxon and the herbicide bromoacil were separated.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 7 (1995), S. 355-363 
    ISSN: 1040-7685
    Keywords: basic drugs ; capillary electrophoresis ; cyclodextrin derivatives ; separation of enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of seven differently methylated β-cyclodextrin derivatives and of pure β-cyclodextrin (β-CD) on the enantiomeric resolution by capillary electrophoresis of six basic chiral pharmaceuticals is investigated. The methyl substitution pattern affects enantioselectivity much more than other experimental parameters. The purity of the used cyclodextrin derivatives is analyzed by successive hydrolysis, reduction, acetylation, and GC/MS of each CD derivative and by MALDI-TOF mass spectrometry. © 1995 John Wiley & Sons, Inc.
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  • 6
    ISSN: 1040-7685
    Keywords: Enantiomers ; gas chromatography ; cyclodextrin derivatives ; temperature dependence ; capillary columns ; selectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of dilution of the chiral stationary phase octakis (3-O-butyryl-2, 6-di-O-pentyl)-γ-cyclodextrin in the achiral polysiloxane OV-1701 on the separation factor was investigated over a wide concentration range. The loss in enantioselectivity was only negligible down to a dilution of 50% (w/w), since the separation factor vs. concentration curves levels off at higher concentrations. Because of the strong temperature dependence of the separation factors, the properties of short columns (10 m and 4.5 m) were evaluated. These short columns, which allow operation at low temperatures and lead to enhanced separation factors were found to be appropriate for the separations of simple mixtures, because the gain in selectivity exceeded the loss in separation efficiency. For complex mixtures, the higher efficiencies of columns of at least 25 m in length were still necessary. A plot of In α vs. 1/T did not yield straight lines, but showed a significant curvature, leading to considerable relative errors if thermodynamic data were derived from these plots.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 530-536 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Heptakis(2-O-methyl-3,6-di-O-pentyl)-γ-cyclodextrin ; Mixed cyclodextrin derivatives ; Phenoxypropionic acid herbicides ; Polychlorinated pesticides ; Enantiomer separation of chlordane ; Organophosphorus pesticides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of phenoxypropionic acid type herbicides have been resolved by capillary gas chromatography employing modified cyclodextrins as chiral stationary phases. Excellent separations were obtained with columns containing a 1:1 mixture of per-O-pentylated and per-O-methylated γ-cyclodextrin.The enantiomers of the methyl esters of mecoprop and dichlorprop were also resolved on octakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin. On this phase the order of elution of the enantiomers was temperature-dependent, the elution order being reversed as the temperature passed through the isoenantioselective temperature. This is the first time such behavior has been observed with cyclodextrin derivatives.The enantiomers of the polychlorinated polycyclic pesticides cis- and trans-chlordane, oxychlordane, heptachlor, heptachlorepoxide, and three chiral organophosphorus pesticides could be resolved using selectively derivatized cyclodextrin derivatives.
    Additional Material: 11 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 113-120 
    ISSN: 0935-6304
    Keywords: Enantioselective GC of chlorinated bis(propyl) ethers ; environmental analysis ; contamination of the Elbe River ; cyclodextrin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Cyclodextrin derivatives are evaluated as chiral stationary phases for the enantiomer separation of chlorinated bis(propyl) ethers (BPE). The enantiomeric composition of the 2,3,2′,3′- and 1,3,2′,3′-isomers of tetrachlorobis(propyl) ether in the Elbe River has been quantitatively determined by enantioselective gas chromatography and coupled gas chromatography/mass spectrometry in selected-ion-monitoring mode. Significant enantiomeric discriminations are observed in selected water samples, indicating that enantioselective bio-degradation mechanisms are at least partly responsible for the overall degradation processes.
    Additional Material: 5 Ill.
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  • 9
    ISSN: 0935-6304
    Keywords: Enantioselective capillary gas chromatography ; Cyclodextrins ; Inverse substitution pattern ; Mechanism of chiral recognition ; Applications ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transferring the site of specific substitution of dipentylated cyclodextrins with methyl or acyl residues from the secondary 3-hydroxyl group to the primary 6-hydroxyl group was expected to provide new information on the mechanism of chiral recognition. The 3-position points towards and the 6-position points away from the cyclodextrin cavity which via inclusion complex formation is supposed to play a major role in chiral separation. The “inverse” 6-O-acyl-2,3-di-O-pentyl-cyclodextrins displayed almost no enantioselectivity but the corresponding 6-O-methyl derivatives are a versatile supplement to the chiral capillary GC phases nowadays available. Among the compounds that could be enantiomerically resolved are alcohols, amino acids, alkyl halides, bicyclic ethers, acetals, olefins, other hydrocarbons and chiral pharmaceuticals.
    Additional Material: 9 Ill.
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  • 10
    ISSN: 0009-2940
    Keywords: Host-guest complexes ; Molecular-dynamics (MD) simulation ; Enantioselective gas chromatography ; Cyclodextrins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The energies of complexation of methyl (R)/(S)-2-chloropropionate [(R)/(S)-2] with heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1) and the structures of the corresponding complexes were determined by molecular-dynamcis (MD) simulations at 300 and 333 K. The geometry of the complexes, the conformations of complexed and uncomplexed 1 and (R)/(S)-2 and the closest H-H distances between host and guest in the complexes were determined from the trajectories. The results correspond to the experimental findings from enantioselective gas chromatography.
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