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New stereoselective GC phases : Immobilized chiral polysiloxanes with (S)-(-)-t-leucine derivatives as selectors

Title data

Abe, Iwao ; Terada, Kennji ; Nakahara, Taketoshi ; Frank, Hartmut:
New stereoselective GC phases : Immobilized chiral polysiloxanes with (S)-(-)-t-leucine derivatives as selectors.
In: HRC : Journal of High Resolution Chromatography. Vol. 21 (1998) Issue 11 . - pp. 592-596.
ISSN 0935-6304
DOI: https://doi.org/10.1002/(SICI)1521-4168(19981101)21:11<592::AID-JHRC592>3.0.CO;2-4

Abstract in another language

New chiral polysiloxanes have been prepared as stationary phases for gas chromatography, with (S)-(-)-t-leucine-t-butylamide, (S)-(-)-t-leucine-(S)-(-)-1-phenylethylamide, (S)-(-)-t-leucine-(S)-(-)-1-(alpha-naphthyl)ethylamide, (S)-(-)-t-leucine-(R)-(+)-1-phenylethylamide, and (S)-(-)-t-leucine-(R)-(+)-1-(alpha-naphthyl)ethylamide as selectors. Immobilization is achieved by radical-induced cross-linking with 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (V-4) and dicumyl peroxide (DCUP) as cross-linking reagents and cured at 170 degrees C. Under these conditions, racemization of S-(-)-t-leucine is less than 4.5% (R) for 1 h curing, while for polysiloxanes with the conventional (S)-(-)-valine selectors about 20% of R-enantiomers are formed by racemization. In the presence of 5% (w/w) V-4 and 6% of DCUP with regard to the phases, 70-80% immobilization is achieved; without V-4, the degree of immobilization is about 50% for both the (S)-(-)-t-leucine and (S)-(-)-valine selectors. As the size of the amide moieties of the selectors increases from t-butyl to 1-(alpha-naphthyl)ethyl, the degree of immobilization decreases. If the curing time is prolonged to 2 h, the extent of racemization increases. The selectivity factors achieved for amino acid enantiomers and similar pharmaceuticals are generally higher than those obtained with the corresponding non-immobilized Chirasil-Val phases.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER33942
Institutions of the University: Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 07 Mar 2016 08:25
Last Modified: 07 Mar 2016 08:25
URI: https://eref.uni-bayreuth.de/id/eprint/31441