Cacodyl oxide

Heat a very small quantity of potassium acetate with an equal bulk of arsenious oxide. The disagreeable and poisonous vapour of cacodyl oxide is evolved. 

Dry acetates mixed with a trace of As203, when heated, give vapours of cacodyl oxide, As2(CH3)40, recognised by smell (caution vapours are very poisonous). 

Dimethyliodoarsine has been prepared by the distillation of cacodyl oxide with concentrated hydriodic acid,1 by the interaction of cacodyl and methyl iodide,2 and by distillation of the periodide, (CH3)4AsIT2.3 Dimethyliodoarsine, among other products, results from the interaction of methyl iodide and powdered arsenic3 and may be obtained by the reaction between potassium iodide and dimethyl-chloroarsine.4 5 When a solution of caeodylic acid, (CH3)2-AsO(OH), and potassium iodide is treated with hydrochloric acid and sulfur dioxide, dimethyliodoarsine settles out as an oil and may be recovered in 90% yield.6,7 The following directions are taken from an improvement of the last method and do not require the isolation of the cacodylic acid.6,8... 

Cacodyl oxide reaction If a dry acetate, preferably that of sodium or potassium, is heated in an ignition tube or test-tube with a small quantity of arsenic(III) oxide, an extremely nauseating odour of cacodyl oxide is produced. All cacodyl compounds are extremely POISONOUS the experiment must therefore be performed on a very small scale, and preferably in the fume chamber. Mix not more than 0-2 g sodium acetate with 0-2 g arsenic(III) oxide in an ignition tube and warm observe the extremely unpleasant odour that is produced. 

TriaOcylarsine Oxides.—Only three compounds pf this type are known — the melliyl, ethyl, and n-propyl derivatives. The first two are formed by direct oxidation of the arsines by atmospheric oxygen, and the methyl compound also results when cacodyl oxide, (Me2As)20, in methyl alcohol solution is treated with methyl iodide and sodium hydroxide. The propyl derivative is formed when tetra- -propyl-arsonium hydroxide is heated in a stream of hydrogen. These oxides exhibit no add properties but are inclined to be feeWy basic, the ethyl compound yielding a nitrate, and the propyl compound a double compound with mercuric chloride. 

Trimethylarsine oxide, (CH8)8AsO, may be obtained either by the action of oxygen on trimethylarsine, or by treating cacodyl oxide in methyl alcohol solution with methyl iodide and sodium hydroxide. It forms deliquescent crystals. When its aqueous solution is saturated... 

Dimethylfiuoroarsine, Cacodyl fluoride, (Cir,.j)2AsF, is obtained by distilling cacodyl oxide with hydrofluoric acid. It is a colourless liquid of repulsive and penetrating odour, insoluble in water. 

Cacodyl oxide is treated with fuming hydroc hloric acid, tlien mixed with an excess of mercuric chloride. The mass is diluted soiiu -what with more hydrochloric acid and the whole distilled, the ( hloride. passing over. ... 

Dimethylbromoarsine, Cacodyl bromide, (CH3)jAsBr.—This compound was first isolated by distilling the double compound of cacodyl oxide and mercuric chloride with very concentrated hydrobromie aeid, and later, by the action of methyl bromide on cacodyl. In recent years the substance has been re-investigated and the following methods of preparation used ... 

Dimethyllodoarsine, Cacodyl iodide, (CH3)2AsI, was origiitally prepared by Bunsen by the distillation of cacodyl oxide with concentrated hydriodic acid, and in small quantity by the interaction of cacodyl and methyl iodide. Distillation of the periodide, Me4AsI.Ij, also gives the... 

By distilling a mixture of arsenious oxide and the potassium salt of a fatty add. In addition to the required cacodyi compound, cacodyl oxide forms a fair percentage of the reaction product in this method. 

Brantley L R, Cromwell T M and Mead J F, Detection of acetate ion by the reaction with arsenious oxide to form cacodyl oxide . Journal of Chemical Education, 1947,24,353. 

It can also be prepared by Cadet s cacodyl reaction. In this method, cacodyl oxide first is prepared by the reaction of K- or Na-acetate with arsenic trioxide, and this is then oxidised with HgO or air to dimethylarsinic acid (Treffler, 1944). 

When an acetate is calcined with a small quantify of As,0, the foul odor cacodyl oxide is developed. 

Oily liquid. Solidifies to large quadratic plates, mp —6". Almost intolerable garlicky odor. Inflames spontaneously in dry air- bp1M, 165". Slightly sol in water. Controlled oxidation with moist air yields cacodyl Oxide and cacodylic acid. Reduction with tin and HC1 yields Erytrarsin (CH3As)4As2 -... 

Analytical Characters.—(1.) AVarmed with HsSOi it blackens. (2.) With silver nitrate a white ciystailine ppt., partly dissolved by heat no reduction of Ag on boiling. (3.) Heated with H2SO4 and GsHjO, acetic ether, recognizable by its odor, is given off. (4.) When an acetate is calcined with a small quantity of AsaO the foul odor of cacodyl oxid is developed. (5.) Neutral solution of ferric chlorid produces in neutral solutions of acetates a deep red color, which turns yellow on addition of free acid. 

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