Sodium stannite, oxidation

Zinnozydul, n. stannous oxide, tin(II) oxide, -chlorid, n. stannous chloride, tin(II) chloride. -hydrat, n. stannous hydroxide, tin(II) hydroxide, -natron, n. sodium stannite. -reserve, /. stannous oxide resist, -salz, n. stannous salt, tin(II) salt, -verbindimg, /. stannous compound, tin(II) compound. 

Tin forms two series of compounds tin(II) or stannous compounds and tint IV1 or stannic compounds. Tin(ll) oxide, SnO, insoluble in water, is formed by precipitation of an SnO hydrate from an S11CL solution with alkali and later treatment in water (near the boiling point and at constant pH). It is amphiprotic, but only slightly acid, forming stannites slowly with strong alkalis. Sodium stannite is conveniently prepared from... 

This reaction can be employed to remove a primary amino group from an aromatic compound, especially. when the ordinary method of direct reduction of the diazonium compound by sodium stannite or alcohol is not applicable. Although in the application of this method the hydrazine can be prepared as the hydrochloride, and reduced in the same solution, yet it is better to isolate the free base and oxidise it separately, since in the oxidation of the hydrochloride there is a tendency for the hydrazine radical to be replaced by chlorine. 

Mercury diphenyl has been prepared in a number of ways. The most important methods are by the action of sodium on a mixture of bromobcnzene and mercuric chloride 1 from sodium amalgam and phenyl mercuric iodide 2 by the interaction of phenyl mercuric bromide and potassium sulfide2 or phenyl mercuric acetate and sodium stannite 3 from phenyl magnesium bromide and mercuric chloride 4 by the action of phenyl hydrazine on mercury compounds 5 from mercuric chloride and phenyl arsenious oxide 6 and from diphenyl mercuric ammonium acetate and sulfur compounds.7... 

The reduction of diazo compounds to the hydrocarbon may be accomplished by means of stannous chloride, sodium stannite or under certain conditions alcohols act as a reducing agent being themselves thereby oxidized to aldehydes. 

A sensitive test for bismuth(III) ion consists of shaking a solution suspected of containing the ion with a basic solution of sodium stannite, Na2Sn02. A positive test consists of the formation of a black precipitate of bismuth metal. Stannite ion is oxidized by bismuth(III) ion to stannate ion, SnOs. Write a balanced equation for the reaction. 

The possibilities with 4-nitropyridine 1-oxides are obviously complicated. Azoxy-dioxides have been produced by reduction with zinc and acetic acid c and by catalytic hydrogenation , azo-dioxides by reduction with ammonium sulphide warm caustic soda , alcoholic ammonia or benzylamine and caustic soda with sodium nitrite . The azopyridine, its monoxide and dioxide are all formed in the reduction with sodium stannite . Stannous chloride produces the hydrazopyridine dioxide, and zinc and alkali the hydrazo-pyridine . Warm 15 per cent caustic soda converts 4-nitropyridine 1-oxide into 4,4 -azopyridine ... 

If tin and sulfur are heated, a vigorous reaction takes place with the formation of tin sulfides. At 100—400°C, hydrogen sulfide reacts with tin, forming stannous sulfide however, at ordinary temperatures no reaction occurs. Stannous sulfide also forms from the reaction of tin with an aqueous solution of sulfur dioxide. Molten tin reacts with phosphoms, forming a phosphide. Aqueous solutions of the hydroxides and carbonates of sodium and potassium, especially when warm, attack tin. Stannates are produced by the action of strong sodium hydroxide and potassium hydroxide solutions on tin. Oxidizing agents, eg, sodium or potassium nitrate or nitrite, are used to prevent the formation of stannites and to promote the reactions. 

Tin when made anodic shows passive behaviour as surface films are built up but slow dissolution of tin may persist in some solutions and transpassive dissolution may occur in strongly alkaline solutions. Some details have been published for phosphoric acid with readily obtained passivity, and sulphuric acid " for which activity is more persistent, but most interest has been shown in the effects in alkaline solutions. For galvanostatic polarisation in sodium borate and in sodium carbonate solutions at 1 x 10" -50 X 10" A/cm, simultaneous dissolution of tin as stannite ions and formation of a layer of SnO occurs until a critical potential is reached, at which a different oxide or hydroxide (possibly SnOj) is formed and dissolution ceases. Finally oxygen is evolved from the passive metal. The nature of the surface films formed in KOH solutions up to 7 m and other alkaline solutions has also been examined. 

Stannous hydroxide, Sn(OH)2, is formed by adding dilute sodium hydroxide solution to stannous chloride. It is readily soluble in excess alkali, producing the stannite ion, Sn(OH)g . When a solution containing stannite ion is boiled an auto-oxidation-reduction reaction occurs, with deposition of metallic tin and production of the stannate ion, Sn(OH)g- ... 

Propyl stannonic acid is obtained by shaking ethyl bromide with an alkaline solution of potassium hydrogen stannite in the presence of alcohol for fourteen days. It is a white po vder which yields propane, propyl alcohol, propylene, water, and tin oxides wdien heated in the absence of air. The acid forms sodium, potassium, and basic calcium and barium salts. Tin propyl iribromide and trichloride are prepared from it in the usual manner, and boiling with 10 per cent, alkali converts them to the dipropyl oxide. 

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