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Tert-butylcarbamoyl quinine selector

The postmodification strategy, in which apoly(glycydyl methacrylate-co-ethylene dimethacrylate) monolith was activated with hydrogen sulfide to a thiol-modified monolith and subsequently derivatized with an 0-9-(tert-butylcarbamoyl)quinine selector by radical addition reaction, yielded slightly less efficient capillary columns. However, this procedure has the advantage that only minute amount of chiral selector are needed to end-up with a useful enantioselective capillary column [84]. [Pg.93]

Hence, this NMR technique allows us to record the NMR spectrum of a dissolved analyte in the presence of a chromatographic sorbent, and therefore mimic a static chromatographic situation. In the suspended-state HR/MAS NMR experiment, the resolution of the signals of the dissolved analyte will be comparable to that in a solution-state NMR experiment. HR/MAS NMR spectroscopy also allows the acquisition of H NMR spectra of stationary phases bonded to silica supports with high resolution compared to the corresponding solid-state NMR spectra. The HR/MAS H NMR spectrum of a (tert-butylcarbamoyl)quinine selector covalently bonded to silica, suspended in [DJmethanol, shows that a full structure elucidation of the selector is possible (see Fig. 4). [Pg.337]

Replacement of the carbamate group with isosteric functionalities such as an IV-methyl carbamate, urea, or amide group clearly confirmed the favorable qualities of the carbamate group [57], While the introduction of a urea group, as in case of iV-9-(tert-butylcarbamoyl)-9-desoxy-9-aminoquinine selector, instead of carbamate functionality turned out to be virtually equivalent in terms of enantiorecognition capabilities [57,58], the enantiomer separation potential was severely lost on iV-methylation of the carbamate group, like in 0-9-(N-me hy -N-tert-butylcarbamoyl)quinine [32,58], or its replacement by an amide, such as in case of Af-9-(pivaloyl)-9-desoxy-9-aminoquinine selector [57,58], For example, enantioselectivities dropped for DNB-alanine from 8.1 for the carbamate-type CSP, over 6.6 for thein-ea-type CSP, to 1.7 for the amide-type CSP, and 1.3 for the A -methyl... [Pg.20]

FIGURE 1.19 X-ray crystal structures of selector-selectand complexes (ion-pairs) (a) O-9-(P-chloro-fert-butylcarbamoyl)quinine with iV-(3,5-dinitrobenzoyl)-(5)-leucine, (b) tbe pseudoenantiomeric complex of 0-9-( 3-cbloro-tert-butylcarbamoyl)quinidine with N-(3,5-dinitrobenzoyl)-(i )-leucine, (c) 0-9-( 3-cbloro-terf-butylcarbamoyl)quinine with N-(3,5-dinitrobenzoyl)-(5)-alanyl-(5)-alanine, and (d) comparison of tbe complexes of (a) and (c). Most hydrogens have been omitted for the purpose of clarity. (Reprinted from C. Czerwenka et al., Anal. Chem., 74 5658 (2002). With permission.)... [Pg.58]


See other pages where Tert-butylcarbamoyl quinine selector is mentioned: [Pg.91]    [Pg.91]    [Pg.49]    [Pg.51]    [Pg.53]    [Pg.55]    [Pg.60]    [Pg.81]    [Pg.88]    [Pg.89]    [Pg.65]   


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