Ether, silicic

Beryllium compounds (except aluminium beryllium silicates) Bis(chloromethyl)ether (BCME)... 

Ethyl chloride Ethyl ether Ethyl formate 2-Ethyl hexanol Ethyl mercaptan Ethyl silicate Ethylene... 

To a mixture of ethyl 5a-cholestan-3-one 2a-xanthate (2 g, 3.95 mmol) and 100 ml methanol is added sufficient ether to completely dissolve the solids. Sodium borohydride (90 mg, 2.36 mmol) is added directly to the reaction flask and the solution is stirred at room temperature for 4 hr. (The use of an excess of sodium borohydride and an extended reaction time produces 5oc-cholestan-2a,3a-thiirane.) The reaction is diluted with 200 ml ether and washed several times with ca. 100 ml water, dried (MgS04) and the solvent is removed under vacuum. The crude sticky gum is chromatographed on a column of 85 g silicic acid. The hexane eluates contain 5a-cholest-2-ene. Ethyl 5a-cholestan-3a-ol 2a-xanthate is obtained in ca. 30% yield by subsequent elution with benzene hexane (1 7) and the desired ethyl 5a-cholestan-3 -ol 2a-xanthate is eluted with ether hexane (1 3) in ca. 30% yield. 

Methyl silicate, 93 a-Methylstyrene, 93 Methyl-tert-butyl ether, 90 Methyl thiocyanate, 93 Methylthiouracil, 93 Methyltrichlorosilane, 94 Methyl vinyl ketone, 94 Methylal, 89 Metolachlor, 94 Metolcarb, 94 Metorex (Pty) Ltd., 199 Metribuzin, 94 Metronidazole, 94 Mevinphos, 94 Mexacarbate, 94... 

Alternatively, as described in U.S. Patent 3,341,557, 6-dehydro-17-methyltestosterone may be used as the starting material. A mixture of 0.4 g of cuprous chloride, 20 ml of 4 M methylmagnesium bromide in ether and 60 ml of redistilled tetrahydrofuran was stirred and cooled in an ice bath during the addition of a mixture of 2.0 g of 6-dehydro-l 7-methyl-testosterone, 60 ml of redistilled tetrahydrofuran and 0.2 g of cuprous chloride. The ice bath was removed and stirring was continued for four hours. Ice and water were then carefully added, the solution acidified with 3N hydrochloric acid and extracted several times with ether. The combined ether extracts were washed with a brine-sodium carbonate solution, brine and then dried over anhydrous magnesium sulfate, filtered and then poured over a 75-g column of magnesium silicate (Florisil) packed wet with hexanes (Skellysolve B). The column was eluted with 250 ml of hexanes, 0.5 liter of 2% acetone, two liters of 4% acetone and 3.5 liters of 6% acetone in hexanes. 

This reaction mixture is kept between 0°C and -i-5°C for six hours, with agitation and under an inert atmosphere, then 5 cc of a 0.2N solution of acetic acid in toluene are added. The mixture is extracted with toluene, and the extracts are washed with water and evaporated to dryness. The residue is taken up in ethyl acetate, and then the solution Is evaporated to dryness in vacuo, yielding a resin which is dissolved in methylene chloride, and the solution passed through a column of 40 g of magnesium silicate. Elution is carried out first with methylene chloride, then with methylene chloride containing 0.5% of acetone, and 0.361 g Is thus recovered of a crude product, which is dissolved in 1.5 cc of isopropyl ether then hot methanol Is added and the mixture left at 0°C for one night. 

The methyl benzoate thus formed is eliminated by steam distillation, and 2.140 g of crude product are obtained, which are dissolved in 20 cc of methylene chloride. This solution is passed through 10 parts of magnesium silicate, elution being performed with 250 cc of methylene chloride containing 5% of acetone. After evaporation of the solvent 2.050 g of product is recovered, which is recrystallized from isopropyl ether. 

The flotation of sulfidic, oxidic, and salt-type ores and, in special cases, silicate ores can be improved by the use of ether carboxylates as collectors [221,222]. In particular, the flotation of fluorite, barite, and scheelite is mentioned. Special synergistic combinations of ether carboxylates with fatty acids [223] and with vinyl- or alkylsulfonic acid polymer [224] are described. 

A solution of sodium methoxide (80 mmol) in methanol (40 mL) is added to silica gel (2.7 g, 45 mmol) followed by a solution of catechol (13.2 g, 120 mmol) in methanol (40 mL). The resulting mixture is stirred and heated under reflux for 18 h. The methanol is then evaporated and the solid residue washed with ether. The black sohd is dissolved in THF (400 mL) and the resulting solution is heated for 1 h in the presence of charcoal. After filtration and evaporation of the solvent the sodium tris(benzene-l,2-diolato)silicate 80 is isolated as a white powder (12.53 g, 70% Scheme 2.20) [93]. 

The oxidation of both linear and cyclic ethers to the corresponding acids and lactones by aqueous H202 as catalyzed by TS-1 and TS-2 was reported by Sasidharan et al. (241) (Scheme 17 and Table XXXV). The titanosilicates exhibited significantly better activity (about 55% conversion) and selectivity (98%) than chromium silicates, although vanadium silicates totally failed to catalyze the reaction. Such conversions are usually accomplished using either stoichiometric amounts of chromium trioxide, lead tetraacetate, or ruthenium tetroxide as oxidants (242) or catalytic amounts of Ru04 in the presence of... 

PDMS nanocomposites with layered mica-type silicates were also reported.374 A two-step sol-gel process of the in situ precipitation of silica led to the development of siloxane-based nanocomposites with particularly high transparencies.3 5 Some unusual nanocomposites prepared by threading polymer chains through zeolites, mesoporous silica, or silica nanotubes were reviewed.3 6 Poly(4-vinylpyridine) nanocross-linked by octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane was reported.377... 

By comparing the two adsorbents, it turns out that the non-polar character of the petroleum ether is exploited in the extraction from the strong nonspecific active sites of carbon black. On the other hand, the polar character of acetone makes the extraction from the highly strong specific active sites of the siliceous material of the soil possible. The retention time obtained with the mixture is intermediate between those two separate solvents, and the recovery, in turn, is higher. The proper choice of the solvent mixture plays a very important role on the size of the final volume of solution in which the pesticides are collected. 

Silicic acid columns can be used for the separation of mixtures of neutral lipids by elution with hexane containing increasing proportions of diethyl ether (0-100%). The lipids are eluted in the following order ... 

The coordination state of the silyl enol ether in the transition state strongly influences the diastereoselectivity (synlanti). If a ligand is sterically demanding, like phosphoramide 33, a boat-like transition state with a pentacoordinated silicate is formed and affords the syn product in the reaction of trichlorosilyl enol ether with benzaldehyde. In contrast, the less hindered ligand 34 gave the anti product through a chair-like transition state with a hexacoordinated silicate (Scheme 25). 

Isolation of toxins. The digestive glands of shellfish were extracted with acetone at room temperature. After removal of the acetone by evaporation, the aqueous suspension was extracted with diethyl ether. The ether soluble residue was successively chromatographed twice over silicic acid columns with following solvents benzene to benzene-methanol (9 1), and diethyl ether to diethyl ether-methanol (1 1). To avoid degradation of dinophysistoxin-3 by contaminant acid, the silicic acid was washed with dilute sodium hydroxide solution and then with water prior to activation at 110 C. Toxic residue obtained in the second eluates was separated into two fractions... 

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