Hydrosulphite Hydroxide

Reduction to hydroquinone. Dissolve, or suspend, 0-5 g. of the quinone in 5 ml. of ether or benzene and shake vigorously with a solution of 1 0 g. of sodium hydrosulphite (Na2S204) in 10 ml. of N sodium hydroxide until the colour of the quinone has disappeared. Separate the alkaline solution of the hydroquinone, cool it in ice, and acidify with concentrated hydrochloric acid. Collect the product (extract with ether, if necessary) and recrystalhse it from alcohol or water. 

Titanous chloride also reduces sulphurous acid or sodium hydrogen sulphite solution with formation of an orange-yellow solution of hydro-sulphurous acid,5 from which sodium hydrosulphite is obtainable by further treatment with sodium hydroxide solution ... 

Anhydrous hydrosulphites are obtained as products of methods described on p. 225. Commercially the anhydrous sodium salt is manufactured in large quantities on account of its greater stability than the hydrated Na2S204.2Ha0. The latter can be dehydrated by extraction with warm alcohol or acetone at 60° to 70° C. It is also possible to produce the anhydrous salt directly by precipitation of the aqueous solution with alcohol at 60° to 70° C., or even by salting-out the solution at this temperature by the addition of sodium hydroxide, chloride, sulphate, carbonate, nitrate or acetate with sodium hydroxide solution of 50 per cent, concentration the anhydrous salt can be separated even at 20° C.1... 

Selenium is soluble in sulphuric acid, forming a green solution which, in the case of the metallic form, probably contains a compound of composition S03Se (p. 338), and in the case of the red amorphous variety, a polymeric form of this compound.8 The presence of selenium does not affect the electrical conductivity of sulphuric aeicl. Dilute aqueous potassium hydroxide dissolves the red variety, producing a solution which probably contains polyselenides in the presence of sodium hydrosulphite, however, only sodium selenide, Na2Se, is obtained.9... 

Reagents. 1. Hydrosulphite solution prepared by dissolving 3-4 grams of pure powdered sodium hydrosulphite in water with addition of 3 grams of sodium hydroxide and making the volume up to a litre. This solution should be kept away from the light and air (it is convenient to cover it with a layer of petroleum) and as it is unstable, its titre should be determined immediately before it is used. 

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. 

The first process was that of P. Spence and Sons1 in 1903, in which the sulphite was reduced by mixing it with titanium trichloride. The mixture was subsequently poured into caustic soda solution and stable sodium hydrosulphite formed, whilst the titanium was precipitated as titanic hydroxide Ti(OH)4. This hydroxide was afterwards dissolved in hydrochloric acid and reduced by electrolysis... 

Electrochemical reductions in inorganic industry are limited to the large scale manufacture of alkali metal amalgams from which hydroxides, sodium sulphide, hydrosulphite etc. are produced. On the other hand in small scale production electrochemical reductions are frequently applied to the preparation of compounds which are difficult to prepare in a chemical way (metal salts with lower valence, e. g. Ti, Mo, V, U and Cr). 

According to Ochslin it decomposes at 180° C., and when warmed for three hours at 60° to 55° C. with normal sodium hydroxide and sodium hydrosulphite it is converted into arsenaphenylmethylglydne, [C4H4.N(CH3).CH2.C02H]2Asg (p. 359). 

A solution of 8-6 grams of 5-nitro-6-amino-j i-tolylarsinic add in 75 c.c. of water and 6 2 c.c. of lOAT sodium hydroxide solution is cooled to —1° C. and 20-4 grams of sodium hydrosulphite added in one oiJeration. When the reaction is complete the solution is filtered and 8-1 c.c. of hydrochloric acid (density 1 12) added. The arsinic acid separates and is recrystallised from water. It forms colourless needles, containing 1J to 2 mols. of water of crystallisation. It is soluble in methyl alcohol and acetic acid, sparingly soluble in ether, benzene, and petroleum. Its solution in dilute hydrochloric acid gives a chai acteristic deep violet coloration with a drop of dilute solution of potassium dichromate. 

Reduction of tliis compoimd by sodium hydrosulphite in sodium hydroxide solution at 60 C. in a carbon dioxide atmosphere 5delds the diamino-derivative. The product is soluble in water or methyl alcohol, less soluble in ethyl alcohol, insoluble in ether and acetone. It forms a dihydrochloride w hen treated with concentrated hydrochloric acid. 

Dichloro-4-hydroxyphenylarsenoxide (33-9 grams) and 24 9 granrs of 3-amino-4-hydroxyphenylarsenoxide are dissolved in 200 c.c. of methyl alcohol, 125 c.c. of normal sodium hydroxide added, and 2300 c.c. of water. Sodium hydrosulphite (200 grams) is stirred in, and the arseno-compound separates out. It is a bright yellow powder, very soluble in ether, soluble in alcohols and acetone, insoluble in water. It gives clear solutions in hydrochloric acid, and sodium hydroxide or carbonate, but is only slightly soluble in sodium bicarbonate. 

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