Sodium carbonate-silica reactions

A mixture of 22 parts of 1 -ethyl-1,4-dihydro-5H-tetrazol-5-one,45 parts of 1 -bromo-2-chloro-ethane,26 parts of sodium carbonate,0.3 part of potassium iodide and 240 partsof 4-methyl-2 pentanone is stirred and refluxed overnight with water-separator. The reaction mixture is cooled, water is added and the layers are separated. The aqueous phase is extracted three times with dichloromethane. The combined organic phases are dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using trichloromethane as eluent. The pure fractions are collected and the eluent is evaporated, yielding 28.4 parts (80%) of 1-(2-chloroethyi)-4-ethyl-1,4-dihydro-5H-tetrazol-5-one as a residue. 

Sodium beryllium fluoride (Na2BeF4) is water-soluble and sodium aluminum fluoride (Na,AlF6) is water-insoluble. A part of the silicon volatilizes off as silicon tetrafluoride (SiF4), while the other part remains in the residue as silicon dioxide (Si02). Fluorination of silicon is unnecessary and it would be economical to recover all of it as silica. This is accomplished by using soda ash, i.e., sodium carbonate (Na2C03) in the reaction mixture ... 

Formerly derived from the natural mineral lapis lazuli, ultramarine blue pigments have, for more than a century, been manufactured synthetically. The materials used in the manufacture of ultramarines are china clay (a hydrated aluminosilicate), sodium carbonate, silica, sulfur and a carbonaceous reducing material such as coal tar pitch. For the manufacture of the blue pigments, the blend of ingredients is heated to a temperature of 750 800 °C over a period of 50-100 h, and the reaction... 

A mixture of rhodium II) acetate (228 mg, 0.516 mmol), the imidazolidinone (1.70 g, 6.15 mmol), and dry chlorobenzene (20 mL) is heated under reflux for 18 h in a flask fitted with a Soxhlet extraction apparatus into which a thimble is placed containing an oven-dried mixture of sodium carbonate and sand (2 1, 5 g). The progress of the ligand-exchange reaction can be monitored by HPLC (p-Bondapak-CN column, methanol). The resulting blue solution is concentrated under reduced pressure, and the residue is purified by column chromatography (reversed phase silica, Bakerbond Cyano 40 mm prep. LC packing, methanol). 

The different types of admixtures, known to reduce alkali-aggregate reactions, can be divided into two groups those that are effective in reducing the expansion due to the alkali-silica reaction, and those that lower expansions resulting from the alkali-carbonate reaction. For the alkali-silica reaction, reductions in the expansion of mortar specimens have been obtained with soluble salts of lithium, barium and sodium, proteinaceous air-entraining agents, aluminum powder, CUSO4, sodium silicofluoride, alkyl alkoxy silane,... 

Silica is reduced to silicon at 1300—1400°C by hydrogen, carbon, and a variety of metallic elements. Gaseous silicon monoxide is also formed. At pressures of >40 MPa (400 atm), in the presence of aluminum and aluminum halides, silica can be converted to silane in high yields by reaction with hydrogen (15). Silicon itself is not hydrogenated under these conditions. The formation of silicon by reduction of silica with carbon is important in the technical preparation of the element and its alloys and in the preparation of silicon carbide in the electric furnace. Reduction with lithium and sodium occurs at 200—250°C, with the formation of metal oxide and silicate. At 800—900°C, silica is reduced by calcium, magnesium, and aluminum. Other metals reported to reduce silica to the element include manganese, iron, niobium, uranium, lanthanum, cerium, and neodymium (16). 

The reaction was carried out under an argon atmosphere using standard Schlenk techniques. To a suspension of NaH (21.Og, 0.52 mol) in THF (1 L), (R)-BINOL (50.0 g, 0.175 mol) was added. The mixture was stirred for 45 min, cooled down to 0°C and MOMCl (36.5 mL, 0.44 mol) was injected. The solution was allowed to warm to room temperature, treated with saturated sodium carbonate solution (300 mL) and water (100 mL). The mixture was separated and the aqueous phase extracted with diethyl ether (4 X 100 mL). The combined organic fractions were dried (sodium sulfate) and concentrated under reduced pressure to afford the crude product, which was purified by column chromatography (500 g silica gel, eluent w-hexane/ CH2CI2 1 1 CH2C12) to yield the protected BINOL as a colourless solid (53.0 g, 96%). 

Ultramarine blues are prepared by a high temperature reaction of intimate mixtures of china day, sodium carbonate, sulfur, silica, sodium sulfate, and a carbonaceous reducing agent, eg, charcoal, pitch, or rosin. 

Methylcarbamate insecticides have been recently labeled with DNS-C1 [145]. The procedure involves the hydrolysis of the carbamates with 0.1 M sodium carbonate to form a phenol and methylamine [166]. The two hydrolysis products are labeled with DNS-C1 and subsequently detected and determined quantitatively by TLC on silica gel layers by scanning spectrofluorimetry in situ. The reaction conditions were examined, and optimum conditions for hydrolysis and labeling were established [167]. The overall reaction scheme is shown in Fig. 4.62. The phenol derivatives of a number of N-methylcarbamates have been separated by one- and two-dimensional TLC [168], and the fluorescence behaviour and stability of the derivatives have been examined [169]. Most of the DNS derivatives fluoresce at similar wavelengths (excitation, ca. 365 nm emission, ca. 520 nm). The fluorescence spectrum of a typical DNS derivative is shown in Fig. 4.63. The method has been applied successfully to the analysis of low concentrations of carbamates in water and in soil samples with little or no clean-up being required [170,171]. Amounts as low as 1 ng of insecticide can be detected instrumentally. Visual limits of detection are ca. 5-10 ng per spot. 

In a 50-ml three-necked flask are placed the carboxylic acid (0.01 mol), ethyl polyphosphate (6g, PPE) and purified chloroform (5 ml). The mixture is cooled in an ice bath and the flask is connected to a balloon containing ammonia gas ( 3 litres). Air in the flask is replaced with ammonia and the mixture is mechanically stirred at 0-5 °C for 30 minutes and then at room temperature for one and a half hours whereupon the mixture turns very viscous (1). The balloon is removed and PPE (10 g) is added. The stirring is continued at 80 °C until the reaction is complete (usually within several hours) the dehydration is monitored by t.l.c. analysis (1). The mixture is stirred with aqueous 25 per cent sodium carbonate solution (150 ml), and then extracted with benzene (3 x 40 ml CAUTION). The combined organic extracts are dried with sodium sulphate and evaporated. The residual oil is passed through a short column packed with silica gel ( 20g) and the product eluted with benzene. The eluate is evaporated and the residue purified by short path distillation under reduced pressure (Kugelrohr apparatus). 

A mixture of (-)-(R)-N-[(3,4-dihydro-2H-l-benzopyran-2-yl)methyl]-l,3-propanediamine, 2-chloropyrimidine, sodium carbonate and ethanol was stirred for 4 h at reflux temperature. The reaction mixture was evaporated. The residue was purified by column chromatography (silica gel CHCI3/CH3OH 90 10). The eluent of the desired fraction was evaporated and the residue was converted into the hydrochloride salt in 2-propanol. The salt was filtered off and dried in vacuum, yielding (-)-(R)-N-[(3,4-dihydro-2H-l-benzopyran-2-yl)methyl]-N -(2-pyrimidinyl)-l,3-propanediamine dihydrochloride hemihydrate. 

To a slurry of 11.7 g (0.33 mole) of methyltriphenylphosphonium bromide in 150 ml of dry tetrahydrofuran at -35°C was added, over a 15-minute period, 20 ml (0.033 mole) of n-butyl lithium. The reaction mixture was stirred for one hour. To the reaction mixture at -35° to -40°C was added over a 10-minute period a solution of 5.7 g (0.0165 mole) of 3-chloro-5,6-bis(4-methoxyphenyl)-l,2,4-triazine in 50 ml of tetrahydrofuran. The reaction mixture was allowed to warm to ambient temperature and was stirred overnight. A solution of 1.05 g (0.0165 mole) of sodium carbonate in 50 ml of water was added dropwise to the reaction mixture which then was heated at reflux for three hours. The reaction mixture was cooled, poured over ice, and extracted with diethyl ether. The diethyl ether extract was washed with water, dried over anhydrous sodium sulfate, and concentrated. The concentrate was chromatographed over silica gel, with three fractions being collected. After evaporation of solvent, the third fraction solidified MP about 109°-113°C. 

A mixture of 3-(2-bromoethyl)-2-methyl-pyrido[l,2-a]pyrimidin-4-one monohydrobromide, 3-furan-2-yl-methyl-(3H-imidazo[4,5-b]pyridine-2yl)-4-piperidinyl)-amine dihydrobromide, of sodium carbonate and of N,N-dimethylformamide was stirred and heated overnight at about 70°C. The reaction mixture was poured onto water. The product was extracted with trichloromethane. The extract was dried, filtered and evaporated. The residue was purified by column chromatography over silica gel using a mixture of trichloromethane and methanol (94 6 by volume), saturated with ammonia, as eluent. The pure fractions were collected and the eluent was evaporated. The residue was crystallized from acetonitrile, yielding 3-(2-(4-((3-(2-furanylmethyl)-3H-imidazo[4,5-b]pyridin-2-yl)amino)-l-piperidinyl)ethyl)-2-methyl-4H-pyrido[l,2-a]pyrimidin-4-one melting point 202°C. 

A mixture consisting of the Step 4 product (0.773 mmol), thiophene-3-boronic acid (0.938 mmol), tetrakis(triphenylphosphine)palladium(0) (0.004 mmol), 276 mg sodium carbonate dissolved in 1.3 ml water, and 5 ml 1,4-dioxane was refluxed overnight under a nitrogen atmosphere. The reaction was quenched with water, extracted three times with 25 ml CH2C12, dried with Na2S04, filtered, and concentrated. The brown oily residue was purified by chromatography with silica gel using hexane/EtOAc, 1 1, and the product isolated in 48.4% yield. 

Tiemann (T8) studied the dissolution of silica from a siliceous iron ore by sintering the ore with sodium carbonate followed by leaching the sodium silicate with water. The reaction rates were found to be low after sintering for 4 hr at 1450°F. The residual concentrate was analyzed to be 56% iron, corresponding to 88% dissolution of the silica. Partial to complete fusion resulted when the temperature was increased. 

In the second phase of his study, Yamaguchi [28] investigated the corrosion of certain burned refractories by sodium carbonate vapor. He suspended the test piece with a platinum wire from the bottom of an alumina crucible placed upside down. The entire assembly was heated at 1200°C for various times. Included in this part of the study was a fireclay refractory composed of mullite and silica minerals. Mullite reacted with NazO to form nepheline and alumina. The nepheline increased in amount as the remaining soda vapor reacted with the newly formed alumina and the preexistent silica. For refractories composed of mullite and corundum, carnegieite solid solution was the major reaction product. The formation Yamaguchi described resulted when Na2C03 vapor reacted with the alumina liberated from mullite and preexistent as corundum, forming... 

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