共查询到20条相似文献,搜索用时 93 毫秒
1.
键合型纤维素—苯基氨基甲酸酯手性固定相的制备及用于对映异构?… 总被引:8,自引:0,他引:8
采用化学键合法,利用4,4′-二苯基甲基二异氰酸酯作间隔臂,通过纤维素葡萄糖单元上2、3或6-位上的羟基将纤维素衍生物键合在氨丙基硅胶上,制备了键合型纤维素-苯基氨基甲酸酯手性固定相。同时,以微晶纤维素和苯基异氰酸酯为原料,合成了纤维素-三苯基氨基甲酸酯,并以未修饰的硅胶为载体,制备了涂敷型纤维素-三苯基氨基甲酸酯手性固定相。分别对键合型和涂敷型两类手性固定相进行了表征,并首次在纤维素-苯基氨基甲 相似文献
2.
Summary The regularities of the retention of polymethyl- and monoalkylbenzenes on a nonpolar adsorbent (silanized silica gel) with a polar eluent (23 isopropanol-water) have been studied. In contrast to the retention of the same compounds on a polar adsorbent (silica gel with hydroxylated surface) and with a nonpolar eluent (hexane) polymethylbenzenes are retained on silanized silica gel for a shorter time than the corresponding monoalkylbenzene isomers. The retention order of tert.-, sec.- and n-butylbenzenes is the reverse of that observed on silica gel having a hydroxylated surface. The retention order of xylenes, trimethyl- and tetramethylbenzenes is also the reverse of their retention order on silica gel having a hydroxylated surface. All the mixtures of the corresponding homologues and isomers have been separated. 相似文献
3.
Peng GM Wu SQ Fang ZL Zhang WG Zhang ZB Fan J Zheng SR Wu SS Ng SC 《Journal of chromatographic science》2012,50(6):516-522
The chiral selector 6-azido-2, 3-di(p-chlorophenylcarbamoylated) cellulose was synthesized and further chemically immobilized onto 5-μm amino functionalized spherical porous silica gel. It was used as chiral stationary phase in high-performance liquid chromatography. Thirty racemates were successfully separated into enantiomers in either normal phase mode or reversed-phase mode. Good reproducibility and stability of the chiral stationary phase have been demonstrated. 相似文献
4.
Thin layer chromatography in combination with spectrophotometry and titrimetry has been used to evaluate chromatographic characteristics of bauxite constituents. The retention behaviors of four major constituents (Al3+, Fe2+, Ti4+, Si4+) in bauxite mineral have been examined on plain and modified layers of silica gel G, silica gel H and cellulose with mobile phases containing aqueous sodium chloride, formic acid and hydrochloric acid. Ternary separation of Al-Fe-Ti was achieved on chromatographic plates made of silica gel H. The pH effect and presence of impurity elements in samples, nature of stationary phases on the ternary separation and detection limits of bauxite constituents were studied. Silicon in bauxite was detected on cellulose plates. Quantitative determinations of Al3+, Fe2+ and Ti4+ on silica gel H impregnated with sodium formate layers were achieved by titrimetry and spectrophotometry. 相似文献
5.
Ke Wang Hongyan Shang Lin Li Xinlong Yan Zifeng Yan Chenguang Liu Qingfang Zha State 《天然气化学杂志》2012,(3):319-323
In this work,a series of polyethyleneimine(PEI) functionalized commercial silica gel were prepared by wet impregnation method and used as CO 2 sorbent.The as-prepared sorbents were characterized by N 2 adsorption,FT-IR and SEM techniques.CO 2 capture was tested in a fixed bed reactor using a simulated flue gas containing 15.1% CO 2 in a temperature range of 25-100 C.The effects of sorption temperature and amine content on CO 2 uptake of the adsorbents were investigated.The silica gel with a 30 wt% PEI loading manifested the largest CO 2 uptake of 93.4 mg CO 2 /g adsorbent(equal to 311.3 mg CO 2 /g PEI) among the tested sorbents under the conditions of 15.1%(v/v) CO 2 in N 2 at 75 C and atmospheric pressure.Moreover,it was rather low-cost.In addition,the PEI-impregnated silica gel exhibited stable adsorption-desorption behavior during 5 consecutive test cycles.These results suggest that the PEI-impregnated silica gel is a promising and cost-effective sorbent for CO 2 capture from flue gas and other stationary sources with low CO 2 concentration. 相似文献
6.
A novel spherical cellulose adsorbent has been prepared by homogeneous graft polymerization of N,N'-methylenebisacrylamide (MBA) onto cellulose in an ionic liquid, 1-N-butyl-3-methylimidazolium chloride (BMIMC1), which was then partially amine methylated through Mannich reaction to get bifunctionalized materials containing both amide and sulphinate moities. Factors affecting the attachment of functional groups were investigated. The adsorbent was characterized by Elemental Analysis (EA), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Cellulose adsorbent was then tested for its potential applications in the reduction adsorption oftrichloroacetic acid (TCAA) from aqueous solutions. 相似文献
7.
Takateru Kubota Chiyo Yamamoto Yoshio Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2004,42(18):4704-4710
Three polysaccharide phenylcarbamate derivatives [cellulose 2,3-bis(3,5-dimethylphenylcarbamate)-6-(3,5-dimethylphenylcarbamate)/(2-methacryloyloxyethylcarbamate), cellulose 2,3-bis(3,5-dichlorophenylcarbamate)-6-(3,5-dichlorophenylcarbamate)/(2-methacryloyloxyethylcarbamate), and amylose 2,3-bis(3, 5-dimethylphenylcarbamate)-6-(3,5-dimethylphenylcarbamate)/(2-methacryloyloxyethylcarbamate)] with vinyl groups were prepared and coated onto silica gel to immobilize them via radical copolymerization with 2,3-dimethylbutadiene. The copolymerization efficiently proceeded, and the coated polysaccharide derivatives were mostly immobilized on the surface of the silica gel. The immobilized polysaccharide derivatives showed high chiral recognition abilities similar to those of the corresponding coated polysaccharide derivatives. They could be used with an eluent containing chloroform, which dissolved the polysaccharide derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4704–4710, 2004 相似文献
8.
The application of thin-layer chromatography to the separation of 13 steroids, including androstanes, 4-androstenes and 5-androstenes, using silica gel and 1,2-propanediol-impregnated cellulose is described. After group-wise separation of various C19 steroids on silica gel, the 3-hydroxy epimers of 5alpha-androstanes and 5-androstenes can be separated by thin-layer chromatography on impregnated cellulose plates. The chromatographic procedure is rapid and makes the prior formation of steroid derivatives unnecessary. 相似文献
9.
Summary During LSC of naturally occurring monoterpene hydrocarbon mixtures from essential oils using silica gel as adsorbent alterations in the composition of the mixtures were observed by means of gas chromatography. Impurities (metals) and active sites on dried silica gels were found to be responsible for a series of isomerizations of a number of the constituents. After purification by washing the silica gel with acid and base and after deactivation of the dried silica gel by adding water (5%) the isomerization processes could be avoided. This was tested by means of the monoterpene hydrocarbon mixtures of three essential oils and a number of pure monoterpene hydrocarbons. 相似文献
10.
本文利用三甲基氯硅烷与硅胶表面羟基反应的方法制备了甲基化硅胶。测定了亲水硅胶和甲基化硅胶的热处理对其自四氯化碳中吸附乙酸的等温线的影响,并配合有热重分析(TG)和红外光谱(IR)的测定。结果表明:(1)甲基化后的硅胶对乙酸的吸附能力大大下降;(2)甲基化硅胶的热处理温度达500℃时吸附能力完全恢复到甲基化前的硅胶的水平,甲基化层明显开始破坏的温度为450℃;(3)甲基化硅胶高温处理后吸附能力得以恢复的主要原因是重新形成表面自由羟基。 相似文献
11.
The methylated silica gel has been produced by the reaction between the surface silanol groups and Clsi(CH3)3 vapor.The adsorption isotherms of acetic acid from carbon tetrachloride onto silica gel and emthylated silica gel heated at various temperatures have been determined at 25℃,and the above mentioned silica gels have been studied by TC and IR.The results indicate:(1) The adsorption of acetic acid from carbon tetrachloried onto methylated silica gel decreased greatly,probably because the concentration of the free hydroxyl groups for methylated silica gel decreased greatly as the IR shows.(2) As the methylated surface was destroyed at 450℃,the adsorption ability was restored when the methylated silica gel treated at>500℃.(3) So long as the methylated silica gel was treated at high temperature,the adsorption ability could be restored owing to that surface free hydroxyl groups were reproduced. 相似文献
12.
Pasilis SP Kertesz V Van Berkel GJ Schulz M Schorcht S 《Analytical and bioanalytical chemistry》2008,391(1):317-324
Desorption electrospray ionization mass spectrometry (DESI-MS) was investigated as a method to detect and identify peptides from tryptic digests of cytochrome c and myoglobin separated on ProteoChrom HPTLC Silica gel 60 F(254s) plates and ProteoChrom HPTLC Cellulose sheets. Full-scan mass spectra and data-dependent tandem mass spectra were acquired in separate plate scans and used to identify peptide ions. Peptide distributions along the development lane were mapped for each separated protein digest. Signal levels ranged over several orders of magnitude. In general, highest signal levels were obtained for the peptides with the highest R (f) values on a plate, while peptides with very low R (f) values were often not detected. Sequence coverages for cytochrome c were 58% for the digest separated on the silica gel plate and 72% for the separation on the cellulose sheet; myoglobin sequence coverages were 62% and 68% on silica gel and cellulose, respectively. Weak correlations between peptide hydrophilicity and R (f) values on the silica gel and cellulose plates were found, with the more hydrophilic peptides having lower R (f) values. 相似文献
13.
77As(III) and77As(V) were separated from neutron-irradiated GeO2 by a thin-layer chromatographic method, in which silica gel was used as adsorbent and a 2∶1 mixture of methanol and 5N HCl
as developer. The Rf values of these nuclides were as follows: 0.00 for77Ge, 0.50 for77As(III) and 0.94 for77As(V). The influence of As(III) carrier added before the separation was investigated on the oxidation state of77As recoiled from the parent nuclide. The radiochemical purity of77As thus separated was more than 99.9% and the activity due to77As could easily be eluted with water from the adsorbent, with 93% recovery. 相似文献
14.
15.
《液相色谱法及相关技术杂志》2012,35(7):1285-1290
Abstract A chiral separation of N(+)-and S(-)-benzyl-3-tetrahydrofuroate (I) and p-nitrobenzyl-3-tetrahydrofuroate (II) using a Chiralcel OB© (cellulose tribenzoate) column with a hexane/2-propanol (60:40 v/v) mobile phase is described. Enantiomeric purity of R(+)-I was evaluated using the same chromatographic conditions. I was also separated using a Chiralspher© (polyamides bonded to silica gel) column with an ethanol/distilled water (50:50 v/v) mobile phase. 相似文献
16.
Z. Šoljić 《Chromatographia》1978,11(8):430-433
Summary The mechanism of interaction between inorganic substances and thin layers of microcrystalline cellulose and silica gel is
considered. It is observed that the majority of the phenomena associated with the chromatographic behaviour of inorganic substances
are not in agreement with the hypothesis of a partition mechanism on cellulose, nor with the ion-exchange mechanism on silica
gel. It is concluded that the mechanism of interaction between inorganic substances and cellulose or silica gel is based on
adsorption, due to electrostatic forces, primarily through hydrogen bonds between OH-groups of the adsorbent and basic ligands
of inorganic complexes. The chromatographic process comprises a continual dynamic adsorption—desorption equilibrium of the
complexes between the mobile phase and the stationary phase. 相似文献
17.
Ming-Xian Liu Xiang-Xiang Deng Da-Zhang Zhu Hui Duan Wei Xiong Zi-Jie Xu Li-Hua Gan 《中国化学快报》2016,27(5):795-800
Magnetically separated and N, S co-doped mesoporous carbon microspheres (N/S-MCMs/Fe3O4) are fabricated by encapsulating SiO2 nanoparticles within N, S-containing polymer microspheres which were prepared using resorcinol/formaldehyde as the carbon source and cysteine as the nitrogen and sulfur co-precursors, followed by the carbonization process, silica template removal, and the introduction of Fe3O4 into the carbon mesopores. N/S-MCMs/Fe3O4 exhibits an enhanced Hg2+ adsorption capacity of 74.5 mg/g, and the adsorbent can be conveniently and rapidly separated from wastewater using an externalmagnetic field. This study opens up new opportunities to synthesize welldeveloped, carbon-based materials as an adsorbent for potential applications in the removal of mercury ions from wastewater. 相似文献
18.
It was found, that the addition of silica gel to PCl3 prevents its oxidation and acts as an adsorbent of Pv impurities. The concentration of Pv impurities is diminished below 0,1% calculated as H3PO4. The velocity of purification depends on the kind of silica gel, on its amount and on the volume of the liquid above the adsorbent layer. For the purification of technical grade PCl3 with an impurity level below 1% H3PO4 the small pore or middle pore silica gel in amounts of 10% in relation to PCl3 may be used. In case of PCl3, oxidated to a level of 2.6% Pv, as H3PO4, the velocity of purification was higher for the middle pore silica gel. An attempt is made to explain the action of silica gel on theoretical backgrounds. 相似文献
19.
Kejiang Hu Jerald S. Bradshaw N. Kent Dalley Krzysztof E. Krakowiak Naijun Wu Milton L. Lee 《Journal of heterocyclic chemistry》1999,36(2):381-387
Allyloxy-substituted macrocyclic dibenzodicyclohexanotetraamide 2 was prepared by the following sequence. MonoBoc-protected chiral 1,2-cyclohexanediamine ( 3 ) was treated with isophthaloyl chloride followed by removal of the Boc group to form bisisophthalamide 5. Compound 5 was then treated with allyloxyphthaloyl chloride to form the macrocyclic tetraamide 2 in a 56% yield. Chiral selector 2 was converted to its ethoxydimethylsilane derivative and heated in a suspension of silica gel and toluene to form the chiral macrocycle-containing silica gel phase 1. This phase separated the enantiomers of (±)-α-methylbenzylamine and (±)-DL-α-aminobutyric acid methyl ester in a liquid chromatograph. 相似文献
20.
Spange S Kunzmann D Sens R Roth I Seifert A Thiel WR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(17):4161-4167
Azamethine dyes of the merocyanine type [4-(N,N-di-n-butylamino)-2-methylphenyl][2,4-di-keto-3-[N'-(n-hexyl)]-5-cyano-6-methyl-3-pyridinio]-1-azamethine (1) and [4-(N,N-diethylamino)-2-(N'-tert-butylcarboxy)-amidophenyl]-[2,4-diketo-3-[N"-(n-hexyl)]-5-cyano-6-methyl-3-pyridinio]-1-azamethine (2) have been used as surface-polarity indicators for gold-cluster-functionalized silica particles. Their UV/Vis absorption maxima range from about lambda=600 to 700 nm as a function of solvent polarity and are clearly separated from the surface plasmon UV/Vis absorption band of gold (lambda approximately 520-540 nm). Solvatochromism of both dyes has been investigated in 26 solvents of different polarity. The positive solvatochromic band shifts of 1 and 2 can be well expressed in terms of the empirical Kamlet-Taft solvent polarity parameters alpha and pi*. They are mainly sensitive to the dipolarity/polarizability (pi* term; 70-75 %) and HBD (hydrogen-bond donating) acidity (alpha term) of the solvent. Both dyes adsorb readily on functionalized silica samples from solutions in 1,2-dichloroethane or cyclohexane. The surface polarities of gold-cluster-functionalized silica particles, with and without co-adsorbed L-cysteine and poly(ethylenimine), have been investigated by using these solvatochromic dyes. The specific interaction of dye 2 with cysteine has been examined independently by quantum-chemical calculations by using the AM1 and PM3 methods. 相似文献