Potassium sulphite

CH OfiSj, H2C(S03H)2- a colourless, crystalline solid which readily absorbs water vapour decomposes on distillation. The potassium salt is prepared by heating methylene chloride with an aqueous solution of potassium sulphite under pressure at 150-I60" C. The free acid is obtained by decomposing the sparingly soluble barium salt with sulphuric acid. The aryl esters are very stable, but the alkyl esters decompose on heating to give ethers. Resembles malonic acid in some of its reactions. 

Magnesium fluorosilicate Mercuric chloride Nickel chloride Nickel sulphate Potassium bisulphate Potassium bisulphite Potassium sulphite Silver nitrate... 

Potassium pemnanganate Potassium nitrite Potassium nitrate Potassium sulphite Potassium stannate IV Potassium sulphate Poptassium metabisulphite Potassium peroxodisulphate Potassium tellurate (IV) Potassium pyrophosphate... 

Thus, in acetic anhydride (Ac20) acetyl chloride (AcCl) is a solvoacid (here acetoacid) and potassium acetate a solvobase (here acetobase) in liquid S02 thionyl chloride (SOCl2) is a solvoacid (here oxoacid) and potassium sulphite a solvobase (here oxobase). In the cationotropic system of anhydride [t = 22 at 20° C pKs = - log ... 

In this reaction phenylhydroxylamine behaves like a secondary amine. To the class of nitrosohydroxylamines there belong also the so-called isonitramines and the compound of nitric oxide and potassium sulphite. 

The yields of arenesulphonic acids (-80%) via the reaction of activated haloarenes with potassium sulphite under phase-transfer catalytic conditions [62, 63] are no better than conventional non-catalytic methods, although reaction conditions are less severe. There is evidence that indicates the initial attack by the sulphite anion is at C-5. Surprisingly, tri-n-butylamine is a better catalyst, producing higher yields (>90%). 

Sulphur chloride or dichloride can convert potassium sulphite into trithionate,5 the equations being... 

The tetrathionates are converted by nascent sulphur into penta-thionates, whilst by potassium sulphite solution they are reduced to trithionate.7 The latter reaction explains the erroneous assumption that trithionate could be directly produced by the action of iodine on an aqueous mixture of potassium thiosulphate and sulphite8 (see p. 210). With equivalent quantities of tetrathionate and sulphite, the reaction leads to the equilibrium 9... 

Nitrilosulphonic Acid, N(S03H)3, has long been known in the form of its potassium salt, which is precipitated in crystalline condition when a mixture of potassium nitrite and potassium sulphite (1 mol. 3 mols.) is allowed to stand ... 

Selenosulphuric Acid or Thioselenic Acid, H2SSeOa.—Salts of this acid are obtained when finely divided selenium is dissolved by warming with an aqueous solution of an alkali sulphite, potassium sulphite being the most satisfactory 4... 

Selenotrithionic Acid, H2SeS20B.—In the preparation of potassium selenosulphate as just described, a certain small amount of a potassium selenotrithionate, K2SeS2O0, is obtained, which generally crystallises first on evaporation of the solution at the ordinary temperature. The yield is much better if potassium hydrogen sulphite is also present with the selenium and normal potassium sulphite.2... 

Potassium sulphite solution is first prepared by saturating a solution of 10 grams of potassium hydroxide in 50 c.c. of water with sulphur dioxide in the cold and neutralising with powdered potassium carbonate (10 grams of potassium hydroxide and 50 c.c. of water require about 18 grams of potassium carbonate). 

F. Raschig mixed a mol of potassium nitrite dissolved in as little water as possible with a well-cooled soln. of 2 mols of potassium hydrosulphite, and added a cold sat. soln. of about 2 mols of potassium chloride. In 24 hrs., the needle-like crystals of nitrilosulphonate were separated from the crystalline crust of the nitrilo-disulphonate by washing. The latter salt can be purified by crystallization from warm water rendered alkaline by ammonia or potassium hydroxide. A. Claus also made the salt by mixing 4 mols of potassium sulphite and one of potassium nitrite. The soln. is filtered from the crystals of nitrilosulphonate, and in about 10-12 hrs. it deposits crystals of dipotassium nitrilodisulphonate. He also made the same salt by crystallization from a soln. of potassium nitrosyl sulphonate in warm water. 

Sodium potassium sulphite, NaKSOs.—When sodium hydrogen sulphite is neutralized by potassium hydroxide or carbonate, a double sulphite of sodium and potassium is formed. It is known as anhydrous salt, and also as monohydrate and dihydrate. For the heat of solution of the anhydrous form Hartog 12 gives —1-19 Cal. 

Potassium sulphite, K2S03.—The sulphite can be prepared by passing sulphur dioxide into a solution of potassium carbonate till evolution of carbon dioxide ceases or by dissolving a known weight of potassium hydroxide in water, saturating with sulphur dioxide, and adding an equal weight of the hydroxide. Evaporation of the solution yields the rhombic dihydrate, which is transformed into the anhydrous salt at 120° C., a white solid with heat of formation 272-6 Cal.7 A monohydrate is also known. 

Potassium thiosulphate, K2S203.—The thiosulphate is prepared by boiling potassium sulphite in aqueous solution with sulphur. Its heat of formation is 278-0 Cal.2 A monohydrate has been isolated.3... 

Potassium hyposulphite, K2S204.—The hyposulphite is obtained in the form of trihydrate by a method analogous to that employed for the sodium salt. A solution of potassium sulphite containing free sulphurous acid is treated with zinc-dust, and filtered after precipitation of the zinc by addition of slaked lime. On mixing the solution with alcohol, the trihydrate is deposited in very unstable yellow crystals. When boiled with acetone or methyl alcohol and dried in vacuum, they... 

Potassium cuproferrocyanide, K2Cu2Fe(CN)6, is prepared 1 by boiling cuprous cyanide with a solution of potassium ferrocyanide containing a little potassium sulphite or by boiling cuprous chloride or potassium cuprous cyanide with potassium ferrocyanide solution. When rapidly cooled, the solution yields colourless cubes, but the crystals are liable to undergo partial oxidation, turning yellow or brown in colour. 

The solution is intensely violet, but the salt is readily precipitated by addition of alcohol. Reduction with alkaline hydroxylamine chloride solution yields potassium aquo penta-ferrocyanide, K3Fe(CN)5.H20, whilst with alkaline potassium sulphite the sulphito penta-ferrocyanide, K5Fe(CN)5.S03, is obtained. 

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