Sodium hydrogen carbonate preparation

Acetylene is passed for 1 hr through a mixture consisting of 0.5 g (72 mg-atoms) of lithium in 100 ml of ethylene-diamine. A solution prepared from 1 g (3.5 mmoles) of rac-3-methoxy-18-methylestra-l,3,5(10)-trien-I7-one and 30 ml of tetrahydrofuran is then added at room temperature with stirring over a period of 30 min. After an additional 2 hr during which time acetylene is passed through the solution the mixture is neutralized with 5 g of ammonium chloride, diluted with 50 ml water, and extracted with ether. The ether extracts are washed successively with 10% sulfuric acid, saturated sodium hydrogen carbonate and water. The extract is dried over sodium sulfate and concentrated to yield a solid crystalline material, which on recrystallization from methanol affords 0.95 g (87%) of rac-3-methoxy-18-methyl-17a-ethynyl-estra-l,3,5(10)-trien-17jB-ol as colorless needles mp 161°. 

A sodium hydrogen carbonate - sodium carbonate buffer is to be prepared with a pH of 9.40. 

Dimethylphenylsilyl lithium (1 mmol, above THF solution) was added to copper(i) iodide (0.5 mmol) at — 23 °C, and the mixture was stirred at this temperature for 4h. The enone (0.75-0.5mmol) was then added, and stirring was continued at —23 °C for 0.5 h. The mixture was then poured on to ice(25 g)/HCl(5 ml), and extracted with chloroform (3 x 25 ml). The combined extracts were filtered, washed with HCI (25ml, 3m), water (25 ml), saturated sodium hydrogen carbonate solution (25 ml) and water (25 ml), and dried. Concentration and purification by preparative t.l.c. (eluting solvent 3 7 ether petrol) gave the /J-silylketone (40-99%). 

A solution of 4,4-dimethyl-l-trimethylsilylcyclohex-l-ene (2 mmol) in dichloromethane (100 ml) was added over 6 h with stirring to a mixture of acetyl chloride (6 mmol) and A1C13 (6 mmol) in dichloromethane (20 ml). After a further 15 min, the mixture was washed with saturated sodium hydrogen carbonate solution and brine, dried and concentrated in vacuo. Preparative t.l.c. on Si02, eluting with dichloromethane, gave 1-acetyl-4,4-dimethylcyclohex-l-ene (0.154 mmol, 77%). 

Buffer solutions with pH values around 10 are prepared using sodium carbonate (Na2 CO3) and sodium hydrogen carbonate (NaHC03). What is the pH of a solution prepared by dissolving 10.0 g each of these two salts in enough water to make 0.250 L of solution ... 

Transfer the residue prepared as in Section 6.1.1 into a 300-nL separatory funnel with 25 mL of phosphate buffer solution (0.1 M, pH 7.4). Add 10 mL of saturated aqueous sodium chloride and 50 mL of 0.5 M sodium hydrogen carbonate to the funnel and shake the funnel vigorously for 1 min. Add 70 mL of ethyl acetate to wash the aqueous layer to the funnel, shake, separate, and discard the ethyl acetate layer. Repeat this extraction procedure three times. Add 2 mL of phosphoric acid and 20 mL of an acetate buffer solution (0.1 M, pH 4) to the aqueous layer and extract the mixmre with 50 mL of ethyl acetate three times. Combine the extracts and filter into a 500-mL round-bottom flask through 60 g of anhydrous sodium sulfate supported by a plug of cotton wool in a funnel. Concentrate the filtrate to dryness under reduced pressure. 

Nitration of the ester with 90% nitric acid was effected according to a literature method. Examination of the reaction mixture by TLC showed that both expected mononitro derivatives had been formed, and it was allowed to stand at ambient temperature overnight. Ice and dichloromethane were then added, and the separated solvent layer was washed with aqueous sodium hydrogen carbonate, dried, and then freed of solvent by evaporation. The viscous oily residue decomposed and ignited in the flask. The preparation was repeated, but worked up immediately and under nitrogen while still cold, and furnished samples of both of the pine isomeric nitro derivatives. Thermal analysis of these showed both to be thermally stable. It was concluded that the decomposition was due to an impurity formed during the 16 h interval between nitration and work-up. 

Aerosil was converted into the sodium form by treating it with a buffer solution (pH = 8.4) made of sodium hydroxide and sodium hydrogen carbonate solutions, after which it was filtered, washed free of alkali, and dried. This sodium-exchanged aerosil was then suspended in a solution of Ni(en)3(N03)2 prepared by adding the calculated amount of ethylene-diamine to a solution of nickel nitrate. The suspension was agitated for about 30 min and filtered off. The catalyst was then washed and dried at 100°C. 

H. R = COPh) has been prepared from the nitrile (99, R = Me) and benzoyl chloride followed by treatment with sodium hydrogen carbonate. This compound (98, R = R = Ph, R - Me, R = H, R = COPh) undergoes a 1,3- polar cycloaddition with dimethyl acetylene-dicarboxylate in boiling benzene during 10 minutes, yielding the pyrrole... 

Mercury fulminate prepared by one of the methods outlined above is tested to check the acid content and the content of other mercury compounds. When tested with litmus paper, the moist product should give a neutral reaction. A 5 g test sample mixed with 2 g of sodium hydrogen carbonate should not give a black or bluish tint. 

Prepare a solution of 12 g sodium potassium tartrate and 24 g anhydrous sodium carbonate in 250 ml distilled water. Add a solution of 4 g copper sulfate pentahydrate and 16 g sodium hydrogen carbonate in 200 ml distilled water. Separately, prepare a solution of 180 g anhydrous sodium sulfate in 500 ml of boiling distilled water. Combine the two solutions in a volumetric flask and dilute the final solution to 1 liter. Store up to 1 year at room temperature. 

Isopropoxydimethylsilyl)methyl chloride2 is readily prepared from (chlorodimethylsilyl)methyl chloride by treatment with isopropyl alcohol (1.1 equiv) and triethylamine (1.1 equiv) in diethyl ether at room temperature (0.5 hr) and then at reflux temperature (0.5 hr). After filtration of the white salt, the filtrate is washed successively once with water, twice with 0.1 N hydrochloric acid, once with an aqueous 10% solution of sodium hydrogen carbonate and once with water, then dried over sodium sulfate. Filtration and distillation give the product in 80% yield, bp 65-67°C/50 mm, as an air-stable, colorless liquid. The checkers used commercially available material purchased from Aldrich Chemical Company, Inc. 

The first examples of the synthesis of CCs from halohydrins appeared during the early 1930s. In this case, vic-halohydrins were reacted with sodium hydrogen carbonate [190, 191] or sodium alkyl carbonates [192] to afford CCs in good yield (82%), especially when the reaction was carried out under high pressure and temperature. When tetramethylammonium hydrogen carbonate was used in acetonitrile (Equation 7.18) [193], the relevant carbonate could be prepared in high yields under mild conditions. 

Ethyl nitrite may be prepared by dissolving 38 g (0.55 mol) of sodium nitrite in 120 ml of water in a 500-ml flask equipped as above. Dilute 23 g (29 ml, 0.5 mol) of ethanol with an equal volume of water, carefully add 25 g (13.5 ml) of concentrated sulphuric acid and dilute to 120 ml with water. Cool both solutions to —10 °C in an ice-salt bath and add the acid-alcohol mixture to the nitrite solution slowly with constant stirring during about 30 minutes. Transfer the reaction mixture to a cooled separating funnel, run off- the lower aqueous phase, wash the ethyl nitrite layer rapidly with ice-cold 2 per cent sodium hydrogen carbonate solution and dry over anhydrous sodium sulphate. The product may be kept at 0°C as a 50 per cent solution in absolute ethanol if required but should be used as soon as possible. The b.p. of pure ethyl nitrite is 17 °C. 

---