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Material on silica gel

With 2537 k-Light. 1 g (140) in 140 ml anhydrous dioxane is irradiated for 20 hr at room temperature with a Hanau NK 6/20 low-pressure mercury lamp placed in a central water-cooled quartz finger. 0.19 g of (141) crystallize from the crude reaction mixture as described above. Chromatography of the residual material on silica gel with benzene-ethyl acetate (4 1) gives 0.29 g of B-nortestosterone acetate [(142) 28.5 %] and starting material (140). [Pg.329]

Analyze the first crop of triphenylmethanol and the residue from the evaporation of the mother liquors by thin-layer chromatography. Dissolve equal quantities of the two solids (a few crystals) and also biphenyl in equal quantities of dichloromethane (1 or 2 drops). Using a microcapillary, spot equal quantities of material on silica gel TLC plates (Eastman No. 13181) and develop the plates in an appropriate solvent system. Try 1 3 dichloro-methane-petroleum ether first and adjust the relative quantities of solvent as needed. The spots can be seen by examining the TLC plate under a fluorescent lamp or by treating the TLC plate with iodine vapor. From this analysis decide how pure each of the solids is and whether it would be worthwhile to attempt to isolate more triphenylmethanol from the mother liquors. [Pg.326]

Peereboom [52], using various solvents, has separated numerous synthetic and naturally occurring fat-soluble colouring materials on silica gel G, alumina G and kieselguhr G. The results are given in Table 125. [Pg.613]

Wright, R.S. 1971. A reagent for the non-destructive location of steroids and some other lipophilic materials on silica gel thin layer chromatography. J. Chromatogr. 59 220-221. [Pg.610]

The relationship between the BET monolayer capacity of physically adsorbed water and the hydroxyl content of the surface of silica has been examined by Naono and his co-workers in a systematic study, following the earlier work by Morimoto. Samples of the starting material—a silica gel—were heated for 4 hours in vacuum at a succession of temperatures ranging from 25 to 1000°C, and the surface concentration of hydroxyl groups of each sample was obtained from the further loss on ignition at 1100°C combined with the BET-nitrogen area. Two complete water isotherms were determined at 20°C on each sample, and to ensure complete... [Pg.272]

Carbon soot from resistive heating of a carbon rod in a partial helium atmosphere (0.3bar) under specified conditions is extracted with boiling C H or toluene, filtered and the red-brown soln evapd to give crystalline material in 14% yield which is mainly a mixture of fullerenes C q and C70. Chromatographic filtration of the crude mixture with allows no separation of components, but some separation was observed on silica gel... [Pg.247]

Recent developments are leading toward other materials like silica gel or polymers. Certain types of semiconductors are also used as resistive probes. The measurement range of resistive sensors varies depending on materials used. It can be as wide as 0-99% RH. The dynamics are fast enough for normal ventilation applications and the stability of good resistive sensors is high. This does not reduce the need for calibration, but the intervals of successive calibrations can be extended. [Pg.1143]

It is known that not all reactions proceed in the same manner on all adsorbent layers because the material in the layer may promote or retard the reaction. Thus, Ganshirt [209] was able to show that caffeine and codeine phosphate could be detected on aluminium oxide by chlorination and treatment with benzidine, but that there was no reaction with the same reagent on silica gel. Again the detection of amino acids and peptides by ninhydrin is more sensitive on pure cellulose than it is on layers containing fluorescence indicators [210]. The NBP reagent (. v.) cannot be employed on Nano-Sil-Ci8-100-UV2S4 plates because the whole of the plate background becomes colored. [Pg.90]

TLC Analysis. Samples were examined by TLC using standard procedures. Rf values were determined and compared with those of authentic reference materials. Radioactive components were located by scanning (Vanguard Instrument Corp., North Haven, Conn., Model 885) or by autoradiography (Eastman Kodak, Rochester, N. Y., type AA film). The relative Rf value of DCDD on silica gel plates (Brinkmann Instruments, Inc., Westbury, N. Y., type For,4) when developed with n-hexane dioxane acetic acid, 90 10 4, V/V/V, was 0.90. The observed impurity had a relative Rf value of 0.40. On Brinkmann alumina plates, developed with n-hexane, DCDD had a relative Rf of 0.32. Neither system separated the chlorinated dibenzodioxin isomers. [Pg.6]

Simple lipids such as CE, WE, EFA, cholesterol, alcohols, ketones, TG, DG, and MG are usually separated on silica gel plates. Depending on the complexity of the lipid material and the variety of lipid classes present in a single sample, either single-or multiple-solvent systems can be used (Figure 12.4a). Although benzene [45] or... [Pg.310]

The PE extract (4.5 g) was pre-adsorbed on silica gel (10 g) and chromatographed over 50 g silica gel (70-230 mesh) using as eluants PE followed by mixtures of PE/CH2CI2 (1s1) and CHjCl,/acetone (10,20,40,80%), 100 ml fractions being taken. The PE fractions contained glycerides (1H NMR, MS). Fraction 5 (PE/CH Clj) was further purified by preparative TLC (PE/ether, 3 1, 2 x). The low polarity band contained glycerides and a more polar band provided phytol (la) which was shown to be identical with authentic material by Hi NMR and MS comparison. Fractions 6-8 (PE/C Clj) gave after further purification by preparative TLC (PE/ether, 19 1,... [Pg.134]

Ozone is strongly endothermic (A(g) +142.2 kJ/mol, 2.96 kJ/g) and the pure solid or liquid materials are highly explosive. Evaporation of a solution of ozone in liquid oxygen causes ozone enrichment and ultimately explosion [1], Organic liquids and oxidisable materials dropped into liquid ozone will also cause explosion of the ozone [2], Ozone technology and hazards have been reviewed [3], a safe process to concentrate ozone by selective adsorption on silica gel at low... [Pg.1866]

The crude material was purified by flash chromatography on silica gel (20 g) buffered with 1 % triethylamine, using petroleum ether ethyl acetate (9 1) as eluent to give the epoxide as a grey oil (104mg, 0.78 mmol, 78% yield). [Pg.90]


See other pages where Material on silica gel is mentioned: [Pg.425]    [Pg.257]    [Pg.39]    [Pg.289]    [Pg.517]    [Pg.1030]    [Pg.425]    [Pg.257]    [Pg.39]    [Pg.289]    [Pg.517]    [Pg.1030]    [Pg.293]    [Pg.301]    [Pg.315]    [Pg.429]    [Pg.246]    [Pg.247]    [Pg.674]    [Pg.142]    [Pg.558]    [Pg.266]    [Pg.526]    [Pg.36]    [Pg.223]    [Pg.3]    [Pg.40]    [Pg.41]    [Pg.126]    [Pg.208]    [Pg.200]    [Pg.390]    [Pg.402]    [Pg.534]    [Pg.538]    [Pg.78]    [Pg.30]    [Pg.34]    [Pg.250]    [Pg.159]   
See also in sourсe #XX -- [ Pg.693 , Pg.699 ]




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On silica gel

Silica materials

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