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81.
手性液晶聚硅氧烷毛细管柱的制备及应用 总被引:3,自引:0,他引:3
合成了一种手性液晶侧链的聚硅氧烷固定液,并涂制成毛细管柱,此柱适合于分离各种取代基的酚类异构体。对柱效和选择性进行了评价。 相似文献
82.
合成了新型手性Salen配体(H3L)及新型手性Salen双核锌配合物(主体).通过研究主体对咪唑类客体及氨基酸酯类客体的分子识别行为,测定了这些配位反应的缔合常数.主体对咪唑类客体分子识别的缔合常数顺序为:K(Im) >K(2-MeIm) >K(2-Et-4-MeIm).主体对氨基酸酯类客体分子识别的缔合常数顺序为:K(LeuOCH3) >K(ValOCH3) >K(AlaOCH3) >K(SerOCH3),配位数均为2.主体与D、 L型氨基酸酯分子识别反应在不同温度下的缔合常数结果表明,随着温度的升高,对映选择性下降.实验发现反应体系中存在焓熵补偿关系. CD光谱的研究结果也反映了主体对不同客体识别能力的差异. 相似文献
83.
Magnetic field-induced orientation of a chiral side chain liquid crystalline polyacrylate(P-11) was studied by using IR dichroism. For the investigated P-11, it has been shown thatthe magnetic alignment takes place over the entire temperature range between its meltingpoint and clearing point and the orientation level is strongly temperature-dependent, thedevelopment with time of the magnetic orieatation follows an exponeotial-type relation,and the smectic phase state influences the thermal relaxation process in the absence of themagnetic field. 相似文献
84.
Summary The simultaneous stereospecific assay of four stereoisomers of diltiazem hydrochloride in bulk drug and aqueous solution was
developed using HPLC on a Chiralcel OF column. The four isomers were quantitated with good precision by the internal standard
method. The chiral inversion of (+)-cis-diltiazem hydrochloride in vitro, stability of its (2S, 3S) configuration in the solid
and aqueous states was examined by HPLC. Chiral inversion of (+)-cis-diltiazem hydrochloride was not observed in the solid
state, and its (2S, 3S) configuration was stable to heat, humidity and light. Chiral inversion of (+)-cis-diltiazem hydrochloride
(2S, 3S) was observed in aqueous solution under UV, but not in aqueous solution stored at 80°C for 5h nor under visible light
for 10 h. The (+)-cis-diltiazem hydrochloride (2S, 3S) epimerized to (+)-trans-diltiazem hydrochloride (2R, 3S) with a half-life
of 5h in aqueous solution under UV but the reverse chiral inversion of (+)-trans-diltiazem hydrochloride (2R, 3S) to (+)-cis-diltiazem
hydrochloride (2S, 3S) was not observed. 相似文献
85.
Enantiomerically pure iridium complexes with phosphino‐ and (phosphinooxy)‐substituted N‐heterocyclic carbene (NHC) ligands were synthesized. Investigation of their electronic properties showed a similar trans influence of the phosphino (or phosphinooxy) and the NHC units. The complexes were tested in iridium‐catalyzed hydrogenation. While low conversions were observed with unfunctionalized olefins, the catalysts proved to be suitable for hydrogenation of the α,β‐unsaturated ester 20 , allylic alcohol 21 , and imine 22 . The enantioselectivities were, however, moderate. 相似文献
86.
Summary Direct separations of the enantiomers of cetirizine and related compounds have been achieved by reversed-phase HPLC on the
Chiralcel OD-R, a polysaccharide-derived chiral stationary phase; the mobile phase was usually perchlorate solution supplemented
with acetonitrile. Resolution of the enantiomers of cetirizine and related compounds was good. The effect of the acetonitrile
content of the mobile phase was investigated, and the effect of the structure of the chiral compounds on their behavior on
the Chiralcel OD-R column is discussed. 相似文献
87.
Summary The enantioseparation of amphetamine, methamphetamine and various ring-substituted amphetamines by use of a chiral stationary phase carrying immobilized native -cyclodextrin (-CyD) selectors is reported. The system is evaluated for resolving the specified compounds directly without any derivatization and after derivatization with phenyl isothiocyanate (PITC), naphthyl isothiocyanate (NITC) and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). This direct enantioseparation is compared with the features of indirect separation of diasteromeric derivatives after reaction with the optically pure Marfey's reagent employing a simple non-chiral alkyl-silica (RP-8) column. A selection of those methods best suited for each single amphetamine is given.Seventeen different samples of amphetamine, confiscated by the Swedisch police, were analyzed with respect to their enantiomeric composition. Within this set of samples synthesized by the same method no significant deviation from a racemic ratio could be observed. 相似文献
88.
89.
90.
The enantiomers of some amino acids have been separated on commercial chiral TLC plates in reversed-phase mode. The effect
of the pH* of the aqueous-organic mobile phase on the retention and mobility of the enantiomers and on selectivity was investigated.
It was shown that for most of the amino acids investigated the highest enantioselectivity was obtained at pH* 3–4 or 6–7.
The drift and disturbance of the baseline on the chromatograms were also much smaller at pH* 3–4 and 6–7. 相似文献