Sodium sulfite, anhydrous

Physical Properties. Anhydrous sodium sulfite [7757-83-7] Na2S02, is an odorless, crystalline soHd and most commercial grades other than by-product materials are colorless or off-white (331—334). It melts only with decomposition. The specific gravity of the pure soHd is 2.633 (15.4°C). Sodium sulfite is quite soluble in water. It has a maximum solubiHty of 28 g/100 g sol at 33.4°C at higher and lower temperatures, it is less soluble in water. Below this temperature, the heptahydrate crystallizes above this temperature, the anhydrous salt crystallizes. Sodium sulfite is soluble in glycerol but insoluble in alcohol, acetone, and most other organic solvents. 

Chemical Properties. Anhydrous sodium sulfite is stable in dry air at ambient temperatures or at 100°C, but in moist air it undergoes rapid oxidation to sodium sulfate [7757-82-6]. On heating to 600°C, sodium sulfite disproportionates to sodium sulfate and sodium sulfide [1313-82-2]. Above 900°C, the decomposition products are sodium oxide and sulfur dioxide. At 600°C, it forms sodium sulfide upon reduction with carbon (332). 

Ma.nufa.cture. In a typical process, a solution of sodium carbonate is allowed to percolate downward through a series of absorption towers through which sulfur dioxide is passed countercurrently. The solution leaving the towers is chiefly sodium bisulfite of typically 27 wt % combined sulfur dioxide content. The solution is then mn into a stirred vessel where aqueous sodium carbonate or sodium hydroxide is added to the point where the bisulfite is fully converted to sulfite. The solution may be filtered if necessary to attain the required product grade. A pure grade of anhydrous sodium sulfite can then be crystallized above 40°C because the solubiUty decreases with increasing temperature. 

In a patented process, a stirred suspension of sodium sulfite is continuously treated with aqueous sodium hydroxide and a sulfur dioxide-containing gas at 60—85°C, and 96% pure anhydrous sodium sulfite is removed by filtration (336). In another continuous one-step process, substantially anhydrous sodium carbonate and sulfur dioxide are concurrently introduced into a saturated solution of sodium sulfite at pH 6.5—7.6 and above 35°C with continuous removal of sodium sulfite (337). 

Shipment and Storage. Anhydrous sodium sulfite is suppHed in 22.7- and 45.4-kg moistureproof paper bags or 45.4- and 159-kg fiber dmms. Most sodium sulfite is shipped by rail in hopper cars. Sodium sulfite should be protected from moisture during storage. When dry it is quite stable, but when wet it is oxidized by air. 

A solution of 615 g. (3 moles) of /3-bromoethylamine hydrobromide (p. 13) and 416 g. (3.3 moles) of anhydrous sodium sulfite (u. s. p.) (Note) in 2400 cc. of water is concentrated on the steam bath to a minimum volume (thirty-six to forty-eight hours). After the mixture has cooled, the cold moist cake is triturated with 1500 cc. of concentrated hydrochloric acid and collected on an asbestos mat in a Buchner funnel. The precipitate is washed ten times with 150-cc. portions of concentrated hydrochloric acid. The filtrate is mixed well, decanted from precipitated salts if necessary, and concentrated over a free flame to a volume of 600 cc. 

A) Purification of Citral.—In a 4-1. bottle are placed 1 1. of water, 1 kg. of crushed ice, 450 g. of anhydrous sodium sulfite (or an equivalent amount of hydrated sodium sulfite), 320 g. of sodium bicarbonate, and 270 g. (304 cc., 1.78 moles) of commercial citral (Note 1). A tightly fitting stopper is securely wired into place, and the bottle is shaken thoroughly for five to six hours. The solution, which contains very little unchanged citral, is extracted twice with 300-cc. portions of ether (Note 2). 

Anhydrous sodium dithionite, 23 674, 675 Anhydrous sodium perborate, 18 401 Anhydrous sodium sulfite, 23 669-670 Anhydrous sodium sulfate, recovery from brine, 5 801... 

In a 4-1. beaker (Note 1) provided with a mechanical stirrer and thermometer are placed 600 g. (4.76 moles) of anhydrous sodium sulfite, 420 g. (S.O moles) of sodium bicarbonate, and 2.4 1. of water. The mixture is heated on a hot plate at 70-80° and is maintained at this temperature by switching the hot plate off occasionally, while 484 g. (2.54 moles) of -toluenesulfonyl chloride (Note 2) is added in portions of 5-10 g., with stirring, during 3 hours. When addition is complete, the mixture is heated and stirred at 70-80° for 1 hour (Note 3). The mixture is then removed from the hot plate and allowed to stand for 4 to (preferably) 10 hours. 

Fuchsin-Sulfurous Acid TS Dissolve 200 mg of basic fuchsin in 120 mL of hot water, and allow the solution to cool. Add a solution of 2 g of anhydrous sodium sulfite in... 

A solution of 28.8 g. (0.08 mole) of 3/3-acetoxy-5-pregnen-20-one (pregnenolone acetate) (Note 3) in 1.1 1. of dioxane (Note 1) is diluted with 320 ml. of water and placed in a 5-1. three-necked, round-bottomed flask fitted with a mechanical stirrer and a thermometer (Note 4). The stirrer is started and the mixture is cooled in ice. When the internal temperature has fallen to 8°, the cold hypobromite solution is added in a steady stream. The temperature of the reaction mixture is maintained below 10° throughout the reaction. A white precipitate begins to form after 10 minutes, and the solution becomes colorless during 1 hour. The mixture is stirred for an additional 2 hours, and then the excess sodium hypobromite is destroyed by the addition of a solution of 10 g. of anhydrous sodium sulfite in 100 ml. of water (Note 5). 

Anhydrous sodium sulfite disodium sulfite exsiccated sodium sulfite E221 sulfutous acid disodium salt. 

Sodium bisulfite is prepated by teacting sulfut dioxide gas with sodium hydroxide solution. The solid matetial is obtained by evaporation of water. Further neutralization with sodium hydroxide while keeping the temperatute above 33.6°C leads to crystallization of the anhydrous sodium sulfite (below this temperature the heptahydrate form is obtained). 

Synonyms Anhydrous sodium sulfite Disodium sulfite Exsiccated sodium sulfite Sulftech Natriumsulfit (German) Sodium sulfite anhydrous Sodium sulphite Sulfurous acid Disodium salt Sodium salt (1 2)... 

Angelic acid nitrile 220 Anhydrous sodium sulfite 3514... 

Sample preparation 250 p,L Serum + 3-hydroxypropyltheophylline, vortex, add 1.5 g anhydrous sodium sulfite, add 2.5 mL chloroform MeOH 90 10, shake vigorously for 30 s (work quickly to avoid forming a cake of sodium sulfite), centrifuge at 1000 g for 5 min. Remove the organic layer, filter (Whatman No. 1 paper pre-wetted with chloroform), rinse filter with 500 pL chloroform, evaporate the filtrate under a stream of nitrogen at 40°. Take up the residue in 100 p,L dichloroethane and add it to 100 p,L 100 mM ammonium carbonate, vortex for 10 s, centrifuge at 1000 g for 5 min, inject a 10 p,L aliquot of the aqueous layer. 

In a 4-1. beaker (Note 1) provided with a mechanical stirrer and thermometer are placed 600 g. (4.76 moles) of anhydrous sodium sulfite, 420 g. (5.0 moles) of sodium bicarbonate, and... 

To a stirred solution of 10 g. of copper(II) chloride, CuCl2-2H20, in 10 ml. of water is added slowly at room temperature a solution of 7.6 g. of anhydrous sodium sulfite, Na2SOs, in 50 ml. of water. The copper(II) chloride solution first becomes very dark brown, and then white copper (I) chloride slowly separates. After all the sodium sulfite solution has been added and the mixture stirred thoroughly, the copper (I) chloride settles readily and the supernatant liquid is faintly green. The precipitate and supernatant liquid are then poured into about a liter of water to which 1 g. of sodium sulfite and 2 ml. of concentrated hydrochloric acid have been added, and the mixture is stirred well and allowed to stand until aU the copper (I) chloride has settled. The supernatant liquid is carefully decanted and the precipitate is quickly washed onto a suction filter (sintered glass type preferred) with dilute sulfurous acid solution. Care should be taken that a layer of liquid covers the salt in the funnel at aU times. 

Anhydrous sodium sulfite and pyrosulfite, free from sulfate, may be prepared by the method of Foerster. Solutions of the salts are readily oxidized by air. Therefore, the product must not be exposed to air until it is thoroughly dried if a high degree of purity is to be attained. Moist crystals of the pyrosulfite decompose slowly even in the absence of air to form the sulfate and sulfur. An odor of sulfur dioxide over this product will indicate that drying was not complete. Both salts may be kept in a desiccator in a hydrogen atmosphere for several months without showing a test for more than a trace of sulfate. 

To simulate these reactions, a sample of anhydrous sodium sulfite (116.5mg) is initially put under vacuum at 150 C during a night. 

Solution 2. Three and one-half (3.5) grams of anhydrous sodium sulfite is dissolved in 50 ml. of distilled water. To this solution is added 0.75 g. of l-amino-2-naphthol-4-sul-fonic acid. Another solution is prepared containing 45 g. of sodium hydrogen sulfite in 400 mL of distilled water. The sulfite-naphthol-sulfonic acid solution is added to the latter and the mixture diluted to 500 ml. 

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