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161.
TS分子筛催化性能研究Ⅰ.TS-2分子筛催化1,2-丙二醇液相氧化反应的研究①伏再辉尹笃林(湖南师范大学精细催化合成研究所,长沙410081)关键词TS-2分子筛1,2-丙二醇氧化催化氧化自1983年Taramasso[1]首次合成具有ZSM-5结构... 相似文献
162.
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
163.
Summary Three -Cyclodextrin derivatives (-CDs) were synthesized by substituting the 2,6-OH groups of -CD with allyl groups and the 3-OH groups with three different acyl groups (valeryl, heptanonyl, octanoyl). The chromatographic properties of these -CDs as stationary phases for capillary gas chromatography (CGC) were studied. The test results showed that the three -CDs possessed good coating properties and that the capillary columns coated with them exhibited high column efficiency. These -CDs can separate not only the disubstituted benzene isomers but also some racemic compounds. 相似文献
164.
Summary The capillary gas chromatographic retention behavior of -pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before -pinene; only permethylated -cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated -cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances. 相似文献
165.
Summary This paper reports the results of a study on the use of a new polymer-based, strong anion-exchange, stationary phase for rapid
and selective separation of carbohydrates and related compounds by high-pH, anion-exchange chromatography with pulsed amperometric
detection. The new adsorbent has been obtained by direct nitration of 2.8 μm, spherical non-porous highly cross-linked, styrene-divinylbenzene
copolymer beads, followed by reduction of superficially introduced nitro groups with nascent hydrogen and quaternization of
the resultant amino groups with iodomethane. It is reported that by optimizing the ionic strength of the mobile phase, columns
packed with the new anion-exchanger can be successfully employed to separate, either in isocratic or gradient elution mode,
oligosaccharides, positional isomers of gluco-disaccharides, as well as uronic acids and sugar monophosphates. 相似文献
166.
167.
168.
Summary The application of capillary SFC for SIMDIST investigations of paraffins and waxes is reported. Pressure, density and temperature of the mobile phase are optimized to obtain high chromatographic resolution of complex mixtures of industrial products. Isothermal linear pressure programming and asymptotic pressure and density programming are used in the range from 15 to 35 MPa in the isothermic mode above 100°C. SFC chromatograms of natural and synthetic paraffins, microcrystalline wax and candle wax are compared. The retention behaviour of paraffin mixtures and waxes has been investigated on methyl/phenyl and biphenyl capillary columns. The polarity of the stationary phases influences the absolute retention time more than it influences the chromatographic resolution. 相似文献
169.
A new way for synthesizing styrenic type of chiral resins grafting to multidentate ligand has been found. The synthetic scheme is proved to be practical by means of elemental anaysis, IR spectra and metal adsorbility. The resolving power of the new chiral ligand resins coordinated with copper (Ⅱ) as stationary phases has been discussed based on HPLC, and some points of view about the compositions of mobil phase and mechanism of resolution are presented. 相似文献
170.
Resolution of enantiomers by HPLC on cellulose derivatives 总被引:4,自引:0,他引:4
Summary Various polysaccharide derivatives, particularly cellulose derivatives, were synthesized and used as chiral stationary phases
for optical resolution by HPLC after being adsorbed on macroporous silica gel. Cellulose triacetate (CTA-II), which was synthesized
under homogeneous conditions, showed a chiral recognition ability for many racemates. Other cellulose derivatives such as
cellulose tribenzoate (OB), cellulose-trisphenylcarbamate (OC), cellulose tribenzyl ether (OE), and cellulose tricinnamate
(OK) also showed unique chiral recognition. Among other polysaccharide derivatives, curdlan triacetate was also exhibited
an effective chiral recognition.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献