Methanol reaction + silica

If attention at first is confined to the production of methyl silicone from the previously accepted raw materials, the chemical processes must include reduction of silica to silicon, preparation of the methyl chloride from methane or methanol, reaction of the methyl chloride with silicon, and hydrolysis of the methylchlorosilanes. If the same conventions are used as in the discussion of the,Grignard method, and the methanol process for methyl chloride is elected, the steps are ... 

The o,p-dinitrostyrene (1 mmol) and ammonium formate (10 mmol) W ere dissolved in methanol and 10% Pd/ C (5% by wt) was added. The mixture was refluxed under nitrogen for 1 h. Formic acid (0.44 ml) w as added and reflux was continued for 0.5-1 h until the completion of the reaction (tic). The solution was filtered through Celite, evaporated in vacuo and eluted through silica gel with CH2CI2. 

Quinoxaline 1,4-dioxides have also been prepared by condensation reactions carried out on the surface of solid catalysts such as silica gel, " molecular sieves, " or alumina. " As a representative example, " BFO 1 and the P-dicarbonyl compound 16 were combined with silica gel in methanol. The excess methanol was removed by evaporation and the silica gel with adsorbed reagents was allowed to stand for two weeks without drying. The quinoxaline 1,4-dioxide 17 was obtained in 90% yield after elution from a silica gel column. 

Preparation of cholesta-5,7-diene-ia,3/3-diol a solution of 500 mg of the 1,4-cyclized adduct of cholesta-5,7-dien-3/3-ol-ia,2a-epoxideand 4-phenyl-1,2,4-triazoline-3,5-dione in 40 ml of tetrahydrofuran is added dropwise under agitation to a solution of 600 mg of lithium aluminum hydride in 30 ml of THF. Then, the reaction mixture liquid Is gently refluxed and boiled for 1 hour and cooled, and a saturated aqueous solution of sodium sulfate is added to the reaction mixture to decompose excessive lithium aluminum hydride. The organic solvent layer is separated and dried, and the solvent Is distilled. The residue Is purified by chromatography using a column packed with silica gel. Fractions eluted with ether-hexane (7 3 v/v) are collected, and recrystallization from the methanol gives 400 mg of cholesta-5,7-diene-la, 3/3-diol. 

Preparation of 1 -(/3-D-arabinofuranosyl)-2-thiocytosine A solution of 2.0 g of 1 -(2, 3, 5 -0-triacetyl-/3-D-arabinofuranosyl)-2,4-dithiouracil in 100 ml of methanol is saturated with anhydrous ammonia at 0°C. The mixture, in a glass liner, is heated in a pressure bomb at 100°C for three hours. The reaction mixture is concentrated to a gum in vacuo, and most of the byproduct acetamide is removed by sublimation at 60°C/0.1 mm. The residue is chromatographed on 100 g of silica gel. Elution of the column with methylene chloride-methanol mixtures with methanol concentrationsof 2-25% gives fractions containing acetamide and a series of brown gums. The desired product is eluted with 30% methanol-methylene chloride to give a total yield of 0.386 g (30%), MP 175°-180°C (dec.). Recrystallization from methanol-iso-propanol furnishes an analytical sample, MP 180°-182°C (dec.). 

A mixture of 2.3 parts of 2-(4-methoxyphenyl)ethyl methanesulfonate, 4.9 parts of 1-[(4-fluorophenyOmethyl] -N-(4-piperidinyl)-1H-benzimidazol-2-amine dihydrobromide, 3.2 parts of sodium carbonate, 0.1 part of potassium iodide and 90 parts of N,N-dimethylformamide is stirred overnight at 70°C. The reaction mixture is poured onto water. The product is extracted with methylbenzene. The extract is washed with water,dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloro-methane and methanol (98 2 by volume) as eluent. The pure fractions are collected and the eluent is evaporated. The residue is crystallized from 2,2 -oxybispropane, yielding 2.2 parts (48%) of 1 -(4-fluorophenvlmethyl)-N-[1 - [2-(4-methoxvphenyl)ethvl] -4-piperidinyl] -1H-benzlmidazol-2-amine MP 149.1°C. 

Ben2yloxyindolyl-3)-Q -acetvlamino-Q -methylthiopropionic acid methanethiol ester (449 mg) was added to 10 ml of ethanol and further 1 ml of triethylamine was added to the mixture. Then, the reaction mixture was refluxed for 17 hours, after condensation under reduced pressure and subsequent separation of the residue by column chromatography (silica gel, ethyl acetate), 353 mg of methyl -(5-benzyloxyindolyl-3)-Q -acetylamino-Q -methylthio-propionate was obtained as colorless glasslike substance in the yield of 81.5%. Recrystallization of the substance from methanol water afforded 287 mg of crystals. 

From the reaction of 5-0-benzoyl-l,2-0-isopropylidene-o -D-en/t/iro-pentofuranos-3-ulose (prepared in 80% yield by oxidation of 5-0-benzoyl-l,2-0-isopropylidene- -D-xylofuranose (35,36) with ruthenium tetroxide) with an excess of diazomethane in methanol-ether, two main products (m.p. 44°-45°C. and 76°-77°C.), both epoxides, could be isolated by chromatography of the product on a silica column. An... 

To a stirred solution of 4 mmol of the diamide in 40 mL of dioxane (distilled from LiAlH4) and 13 mL of water is added 1 mg of osmium tetroxide. When the solution turns brownish (after about 10 min) 2.06 g (9.2 mmol) of sodium metaperiodale are added at 25 26 "C. The progress of the reaction is monitored by TLC on silica gel coated plastic sheets with CHCI,/diethyl ether/methanol (3.3 0.1) as eluent. When the reaction is complete, the precipitated solid is filtered and the filtrate concentrated in vacuo at 1 Torr. The residue is dissolved in 50 mL of CHC13, dried over MgSO,. and evaporated in vacuo to leave a residue, which is crystallized from a suitable solvent. 

Recently, a study of this rearrangement has been repeated and extended in order to determine the influence of a- and y-substitution on the position of the 68-69 equilibrium in the presence of silica, and the utility of this reaction for a novel and convenient synthesis of highly substituted a, / -unsaturated ketones, by subsequent treatment with CuCl2 in methanol-water136. An ion-pair mechanism can also be suggested for the facile rearrangement of sulfone 70 to 71, a key intermediate in the Hoffmann-La Roche Sulfone Route to Vitamin A137. 

Solid palladium scavengers, PVPy, QTU were pmchased from commercial somces. The mesoporous silica material, S102-SH, was prepared via reaction of SBA-15 (110 A pore diameter) with 3-mercaptopropyltrimethoxysilane (16). Specifically, a toluene suspension of SBA-15 and 3-mercaptopropyltrimethoxysilane was heated at reflux for two days under Ar. Water was then added to promote the cross-linking and the mixture was heated at reflux for an additional day. The sohds were filtered and washed with copious amounts of toluene, hexanes, and methanol to remove unreacted silanes. The solids were finally Soxhlet extracted with dichloromethane at reflux temperature for 3 days, dried, and stored in a nitrogen dry box. The final solid contained 7.5 wt% sulfur (2.3 mmole S/g solid). 

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