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Summary Chiral stationary phases (CSPs) for liquid chromatography were prepared by the way of an activated carbamate intermediate.
The amino group of aminopropylsilyl silica gel was first activated by carbamylation with disuccinimido carbonate (DSC). The
obtained activated carbamate silica gel (ACsil) proved useful as an intermediate for the preparation of urea-type CSPs. The
reaction of ACsil with (S)- of (R)-1-(α-naphthyl)-ethylamine gave naphthylethylurea type CSPs. These CSPs were also obtained
directly from aminopropylsilyl silica gel by its reaction with optically active (S)- or (R)-succinimido 1-(α-naphthyl)ethyl
carbamate (SINEC). Several phenylthiohydantoin amino acid enantiomers and p-bromophenylcarbamyl amino acid enantiomers were
resolved on the CSPs by elution with aqueous mobile phase. 相似文献
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Abstract 2-(4-Alkoxybenzoyloxy)-5-alkylaminotropone and 5-alkoxy-2-(4-alkylaminobenzoyloxy)tropone liquid crystals showed the smectic C phase exclusively. Variable temperature FT-IR spectra indicated that intermolecular hydrogen bonding between the NH and tropone C=O groups assisted the appearance of the mesophase. 4-Alkoxyphenyl 4-alkylaminobenzoates were non-mesogenic. 相似文献
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Akira Mori Nobuo Kato Hitoshi Takeshita Ryuko Nimura Masahiro Isobe Chihiro Jin 《Liquid crystals》2013,40(9):1425-1433
The mesomorphic properties of 2-(4-alkoxybenzoyloxy)-5-alkylaminotropones and 5-alkoxy-2-(4-alkylaminobenzoyloxy)tropones are discussed on the basis of results obtained by X-ray crystallographic and X-ray diffraction studies, as well as temperature-dependent FTIR spectral measurements. The X-ray crystallographic analysis of 2-(4-dodecylaminobenzoyloxy)-5-tetradecyloxytropone (2f) indicated that it formed a head-to-tail dimer through an intermolecular hydrogen bond between the NH and the tropone carbonyl group. The X-ray diffraction study of compound 2f suggested that the molecules formed interdigitated bilayer smectic C phases with a tilt angle of as much as c. 40° to a layer plane. The corresponding benzenoids, however, were non-mesomorphic, with higher melting points than the troponoids. In the troponoids, sigmatropic migration of the benzoyl group weakened the intermolecular hydrogen bonding and assisted the occurrence of mesomorphic properties. 相似文献
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A method (tentatively called ‘the method of equivalent sound source’) of predicting the sound attenuation achieved by multiple barriers with knife edges and/or right-angled wedges is proposed. This paper shows that the sound pressure level in the shadow region behind the multiple barriers can be obtained by successively setting imaginary sound sources for respective edges and/or wedges. The locations of the imaginary sound sources are determined by means of the traditional solution for sound attenuation by a single edge. The calculated results for several kinds of small-scale model, obtained by ‘the method of equivalent sound source’, are compared with experimental results. 相似文献
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Improvement of hearing ability by directional information 总被引:1,自引:0,他引:1
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Determination of carnitine by high-performance liquid chromatography using 9-anthryldiazomethane 总被引:1,自引:0,他引:1
T Yoshida A Aetake H Yamaguchi N Nimura T Kinoshita 《Journal of chromatography. A》1988,445(1):175-182
The high-performance liquid chromatographic determination of carnitine chloride was investigated by using 9-anthryldiazomethane (ADAM) as a pre-column derivatization reagent. Carnitine chloride and the internal standard N,N-dimethylglycine reacted with ADAM to give a stable ester derivative in the presence of sodium dodecyl sulphate (SDS) used to mask the basic function. The ADAM derivative of carnitine was separated from decomposition products of the reagent and related compounds such as amino acid derivatives on a silica gel column eluted with methanol-5% aqueous SDS-phosphoric acid (990:10:1). The calibration plot was linear over a sample concentration range from 0.02 to 100 ng per injection. The detection limit for carnitine chloride was about 1 pg per injection (signal to noise ratio = 4), by fluorometric detection. 相似文献
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Summary A chiral derivatization reagent having activated succinimido carbamate moieties were developed for the optical resolution of enantiomeric amines by high-performance liquid chromatography. Succinimido R-(+)- or S-(–)-1-phenylethyl and R-(+)- or S-(–)-1-(-naphthyl)-ethyl carbamates were synthesized by the reaction of optically active phenylethyl and naphthylethyl amines with discuccinimido carbonate (DSC). These reagents reacted with both primary and secondary amine enantiomers such as amino acids and -amino alcohols to give the corresponding diastereomeric urea derivatives. These diastereomers were efficiently separated by reversed-phase liquid chromatography and detected by their absorption or the fluorescence of the chromophores. The chiral derivatization procedure was applied to the separation and determination of enantiomeric propranolol in serum. 相似文献
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