Sodium suspension, preparation

A solution of sodium methoxide, prepared from sodium (23 g) and dry methanol (500 mL), was added drop-wise at 0 °C to a stirred suspension of aminoacetonitrile hydrochloride (18, 100 g, 1.08 mol) in dry methanol (100 rnL). After stirring for 2 h at rt the precipitated sodium chloride was filtered off and the filtrate concentrated in vacuo. EtOAc (20 mL) was added and evaporated under reduced pressure to remove all traces of methanol. The oily residue was dissolved in dry EtOAc (100 mL) and anhydrous sodium sulfate added. After cooling, the precipitate was filtered off. The solution of crude aminoacetonitrile was used without further purification. This solution was added drop-wise during a period of 1 h to a vigorously stirred, ice-cooled solution of carbon disulphide (100 mL, 1.66 mol) in dry EtOAc (100 mL) under an N2 atmosphere. Continued mechanical stirring and water-free conditions were essential. The mixture was stirred at 0 °C for 1 h. The resultant precipitate was filtered off, washed with EtaO and dried, giving the product 50 as yellow crystals (99 g, 75 % on amount of sodium), m.p. 131 °C dec. IR (KBr) v max 1630, 1500 cm. ... 

Perfluoroalkyltelluration of olefins (typical procedure) Into a suspension of sodium phenyltellurolate prepared from (PhTe)2 (0.3 mmol) and NaBH4 (1.8 mmol) (dissolved in dry ethanol (1 mL) at 0°C for 15 min, 1-octene (6 mmol) and C4F9I (1.2 mmol) were added under Nj at -40°C. The colour of the solution turned from colourless to deep brown, immediately indicating the formation of (PhTe)2. The solution was stirred for 4 h while allowing the temperature to rise to room temperature, affording the product in 81% yield. 

A tetrahydrofuran (THF) solution of sodium cyclopentadienide4 is prepared by adding freshly distilled cyclopentadiene5 to a sodium suspension in THF. The concentration of the resulting pale-pink solution can be determined by titration with acid. 

A suspension prepared from 4.25 g. of 95% sodium borohydride (0.11 mole) and 150 ml. of tetrahydrofuran is cooled in an ice-water bath and stirred while a solution containing 17 ml. (0.13 mole) of boron trifluoride-diethylether in 60 ml. of tetrahydrofuran is added dropwise over a period of 45 minutes. Thirty grams (0.11 mole) of triphenylphosphine is dissolved in 130 ml. of tetrahydrofuran, and this solution is added through a dropping funnel to the cooled suspension (1 hour). The mixture is allowed to warm to room temperature. Solids are collected by filtration, and the crude product is recovered by evaporation of the solvent from the filtrate in vacuo. Yield is 32 g. (100% theory). 

The mixture from Step 1 (3.0 mmol) was added to a suspension of sodium adenine [prepared from adenine (3.0 mmol) and NaH (3.0 mmol) in 25 ml DMF] and the mixture heated to 80 °C 12 hours. The solvent was removed, the residue adsorbed on 3 g silica gel of a 70 g silica gel column, and the mixture eluted using CH2Cl2/methyl alcohol, gradient 96 4 to 94 6. The cis isomer was isolated in 29.9% yield, mp = 200-203 °C trans isomer, 17.6% yield, mp = 186-189°C. H- and i C-NMR, IR, UV-Vis and EIMS data supplied for both isomers. 

The stability of norfloxacin in suspensions prepared from two brands of film-coated tablets has been studied (12). The vehicle consisted of tragacanth, saccharin sodium, sorbitol solution, glycerol, parabens concentrate, peppermint spirit, purified water, and sjrup USP, yielding a final concentration of norfloxacin of 20 mg/ml. The resulting suspensions were chemically stable for 28 days when stored in amber glass bottles at room temperature. 

Table 5 gives another list of results. In a kaolinite suspension prepared in distilled water, different salts were added together with the aluminium sulphate coagulant. The salt concentration in the suspension was always 10 M. The different cations had a chlorine counter-ion and the anions had a sodium counter-ion. In jar tests, the coagulant dose needed for a complete turbidity removal was determined, as was the corresponding E.M. of the floes. In the list of Table 5, only ions which can dissolve easily in the water are mentioned. At the given coagulant dose, the EJM. all had reached their constant values. 

Although lithium and sodium amide are commercially available, the suspensions prepared in liquid ammonia are much more reactive, and most reactions with these bases are carried out in this solvent. Lithium and sodium amide can be obtained in a dry state by completely evaporating the ammonia, the last traces in a water-pump vacuum. The powders obtained are very reactive and must be stored under... 

A suspension of 20.1 g 1,5-dimethoxy-2,4-dinitrobenzene (90.0 mmol) in 117 mL water was stirred under reflux and treated dropwise over 30 min with a solution of sodium polysulfide, prepared by heating 28.6 g Na2S-9H20 (119 mmol) and 6.8 g sulfur (213 mmol) in 120 mL water. The reaction mixture was stirred under reflux for a further 3 h and then cooled and evaporated under reduced pressure at 45°C to give a dark residue. This was extracted several times with warm EtOAc, and the combined extracts were filtered through a short column of silica gel. The eluates were washed with water and evaporated to dryness. The residue was dissolved in 1 N HCl, filtered, and basified with aqueous NaOH to give 11.0 g l-amino-2,4-dimethoxy-5-nitrobenzene, in a yield of 63%, m.p. 126-128°C. 

The sodium acetylide solution thus prepared may be used for a variety of organic syntheses by the addition of alkyl halides, sulfates, sulfonates, ketones, aldehydes, and esters. Where a fine suspension of the dry acetylide is desired in an inert solvent such as ether or a hydrocarbon, the solvent is added to the ammonia solution and the mixture is stirred whde the ammonia is evaporated. Extra solvent must be used to replace that entrained by the ammonia, the last traces of which are removed by a period of refluxing. Such a suspension gives better yields of, for example, propiolic acid (by the reaction with carbon dioxide) than sodium acetylide prepared in any other way. 

To prepare the sodium suspension, heat sodium disks under kerosene in ground-glass-stoppered flasks until they are seen to melt (120 C, caution when working with an oil bath), immediately seal the flasks and shake vigorously. 

Hydroxythiophenes from a-mercapto-carboxylic acid esters. 4-Methylpenta-2,3-dienenitrile added dropwise with stirring during 5 min. to a suspension of methyl sodium sulfidoacetate (prepared from mercaptoacetate and Na-ethoxide in abs. ethanol) in anhydrous ether, and stirred 1 hr. at room temp, after the mildly exothermic reaction has ceased -> 4-hydroxy-2-isopropylthiophene-3-carbonitrile. 

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