Analysis of Chiral Organic Molecules

Berndt, Alexander; Schreier, Peter; Huffer, Manfred

doi:10.1515/9783110867855

Cited by 90 publications

(76 citation statements)

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“…different absorption for left and right circularly polarized light) significantly increases calculated circular polarization. Even though circular dichroism is usually very small, making the difference in the imaginary part of the refractive index on the order of 1×10 -8 (Schreier et al, 1995), here it appeared to be sufficient to produce circular polarization that has the observed phase-angle trend and reaches 0.15% at the phase angle 120°.…”

Section: Scattering By Particles Made Of Optically Active (Chiral) Mamentioning

confidence: 73%

Circular polarization in comets: Observations of Comet C/1999 S4 (LINEAR) and tentative interpretation

Rosenbush

Kolokolova

Lazarian

et al. 2007

Icarus

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Comet C/1999 S4 (LINEAR) was exceptional in many respects. Its nucleus underwent multiple fragmentations culminating in the complete disruption around July 20, 2000. We present circular polarization measurements along the cuts through the coma and nucleus of the comet during three separate observing runs, in June 28-July 2, July 8-9, and July 21-22, 2000. The circular polarization was detected at a rather high level, up to 0.8%. The left-handed as well as right-handed polarization was observed over the coma with the left circularly polarized light systematically observed in the sunward part of the coma. During our observations the phase angle of the comet varied from 61 up to 122°, which allowed us to reveal variations of circular polarization with the phase angle. Correlation between the degree of circular polarization, visual magnitude, water production rate, and linear polarization of comet C/1999 S4 (LINEAR) during its final fragmentation in July 2000 was found.The mechanisms that may produce circular polarization in comets and specifically in comet C/1999 S4 (LINEAR) are discussed and some tentative interpretation is presented.

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Section: Scattering By Particles Made Of Optically Active (Chiral) Mamentioning

confidence: 73%

Circular polarization in comets: Observations of Comet C/1999 S4 (LINEAR) and tentative interpretation

Rosenbush

Kolokolova

Lazarian

et al. 2007

Icarus

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“…After methylation of the residual 6-hydroxy groups, we obtained the desired 2 IϪVII ,3 IϪVII ,6 IϪVI -eicosa-O-methyl-6 I -O-(oct-7-enyl)cyclomaltoheptaose (4). The second strategy, which was adapted from a method described by Bradshaw and co-workers, [48] started from 2 IϪVI -eicosa-O-methylcyclomaltoheptaose (3) heptaose (3). Using sodium hydride and a threefold excess of 8-bromo-1-octene in THF, 3 [49,50] was mono-oct-7-enylated in 72% yield.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, NMR Spectroscopic Characterization and Polysiloxane‐Based Immobilization of the Three Regioisomeric Monooctenylpermethyl‐β‐cyclodextrins and Their Application in Enantioselective GC

Cousin¹,

Trapp

Peulon-Agasse³

et al. 2003

Eur J Org Chem

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2I−VI,3I−VII,6I−VII‐Eicosa‐O‐methyl‐2I‐O‐(oct‐7‐enyl)cyclomaltoheptaose, 2I−VII,3I−VI,6I−VII‐eicosa‐O‐methyl‐3I‐O‐(oct‐7‐enyl)cyclomaltoheptaose, and 2I−VII,3I−VII,6I−VI‐eicosa‐O‐methyl‐6I‐O‐(oct‐7‐enyl)cyclomaltoheptaose were synthesized by selective introduction of an oct‐7‐enyl group at one of the O‐2, O‐3, or O‐6 positions of selectively methylated cyclomaltoheptaose (β‐cyclodextrin, CD) and, depending on the synthetic route, by a subsequent permethylation step. Each of the regioisomeric mono‐oct‐7‐enylated permethylated β‐cyclodextrin derivatives was anchored by hydrosilylation to a hydridomethyldimethylsiloxane copolymer to yield unambiguously O‐2‐, O‐3‐, and O‐6‐bonded chiral stationary phases (CSP) of Chirasil‐Dex, which were evaluated in enantioselective gas chromatography (GC). O‐6‐Chirasil‐Dex displayed slightly inferior enantioselectivity relative to either O‐3‐ or O‐2‐Chirasil‐Dex. The statistical synthesis of the CSP by mono‐oct‐7‐enylation of β‐CD under varying reactions conditions (base, solvent), without the use of hydroxy group protection chemistry, furnished a mixture of O‐6‐ and O‐2‐Chirasil‐Dex in dimethylformamide and predominantly the O‐2‐regioisomer in dimethyl sulfoxide. Chirasil‐Dex, previously formulated exclusively as the O‐6 regioisomer, should be revised as an O‐2‐ and O‐6‐Chirasil‐Dex mixture. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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“…Earlier compendia in this area [1][2][3][4][5] need updating due to important recent advances made in the realm of enantiomeric differentiation. Precise analytical tools for the determination of enantiomeric proportions are important in many contemporary fields associated with various aspects of chirality.…”

Section: Prefacementioning

confidence: 99%

Differentiation of Enantiomers I

Schurig¹

2013

Topics in Current Chemistry

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Analysis of Chiral Organic Molecules

Cited by 90 publications

References 0 publications

Circular polarization in comets: Observations of Comet C/1999 S4 (LINEAR) and tentative interpretation

Circular polarization in comets: Observations of Comet C/1999 S4 (LINEAR) and tentative interpretation

Synthesis, NMR Spectroscopic Characterization and Polysiloxane‐Based Immobilization of the Three Regioisomeric Monooctenylpermethyl‐β‐cyclodextrins and Their Application in Enantioselective GC

Differentiation of Enantiomers I

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