Arsenic trichloride, preparation

Other methods for preparing tertiary arsiaes have been employed, but they have limited usefiilness. These methods include the cleavage of quaternary arsonium compounds (68), the cyclodehydrohalogenation of haloarsines (69), the reaction of dia2onium salts with arsenic trichloride in the presence of a metal such as 2inc or iron (70), and the disproportionation of halo- or dihaloarsines (71). 

Arsenin and Its Derivatives. Arsenin (arsabenzene) [289-31-6], C H As, the arsenic analogue of pyridine, can be prepared by the treatment of l,4-dihydro-l,l-dibutylstaimabenzene with arsenic trichloride (118) ... 

The Bart reaction is successful with a wide variety of aromatic and heterocycHc amines. A variation in which an aromatic amine, in the presence of arsenic trichloride, is dia2oti2ed in an organic solvent (the ScheUer reaction) has also found wide appHcation. Both arsonic and arsinic acids can be prepared by the ScheUer reaction which often gives better yields than the Bart reaction with electron-attracting substituents on the aromatic ring. For the commercial preparation of 4-aminophenylarsonic acid [98-50-0] (arsaniUc acid), C HgAsNO, and 4-hydroxyphenylarsonic acid [98-14-6] C H AsO, the Bnchamp reaction is used ... 

Arsenic standards. Prepare a 1 mgL-1 working standard solution from a 1000 mg L-1 SpectrosoL solution of arsenic trichloride in a 4M hydrochloric acid. 

Arsenic trichloride is used in the preparation of many chloroderivatives of arsenic that have pharmaceutical and insecticide apphcations. 

The compound is generally made from arsenic trioxide by (i) passing chlorine over it or (ii) treating the trioxide with sulfur monochloride, S2CI2. Alternatively it is prepared from arsenic trioxide by distdlation with either concentrated hydrochloric acid or a mixture of sulfuric acid and a metal chloride. Arsenic trichloride may also be prepared by combination of arsenic and... 

Arsenic triiodide is prepared by treating elemental arsenic with a solution of iodine in carbon disulfide. Alternatively, it can be precipitated out from a hot solution of arsenic trioxide or arsenic trisulfide in hydrochloric acid on treatment with potassium or sodium iodide. Also, it is made by the reaction of arsenic trichloride with potassium iodide. 

Arsenic phthalocyanine electronic absorption spectra, 7 69 preparation of, 7 50 Arsenic trichloride, 16 49 preparation of, 7 15... 

Triphenylarsine has been prepared by the action of arsenic triiodide or arsenic trichloride on phenylinagnesium Ijromide... 

The arsenide Cu5As.2 has been prepared by passing a current of carbon dioxide and arsenic vapour over finely divided copper heated to the temperature of boiling sulphur 11 by the action of copper on arsenic trichloride or on arsenic dissolved in hydrochloric acid 12 and by the action of cuprous chloride on arsenic. Lustrous regular crystals of density 7-56 are obtained. These tarnish on exposure to air. When heated it loses arsenic and yields Cu3As, which at a higher temperature also decomposes. Cu5As2 dissolves in nitric acid. It is readily attacked by chlorine or bromine.13... 

Mercury Arsenides.—Arsenic does not dissolve in mercury even at the boiling point,2 nor has an amalgam been obtained by the action of sodium amalgam on moist arsenious oxide 3 or by electrolysis of a solution of arsenic trichloride using a mercury cathode 4 in the latter case arsenic is deposited on the surface of the mercury but does not dissolve. Nevertheless, two arsenides of mercury, which appear to be definite compounds, have been prepared. 

Two-thirds of the requisite amount of arsenious oxide are first added and the remainder after the reaction has progressed for a time, the gas being passed continuously. The arsenic trichloride may be distilled off and does not require purification. The reaction is somewhat violent, however. Arsenic trichloride may also be prepared conveniently by passing carbonyl chloride over a mixture containing 80 per cent, of arsenious oxide and 20 per cent, of carbon heated at 200° to 260° C. the yield is almost quantitative.15... 

In a parallel manner, the reaction between Pb(CNS)3 and arsenic trichloride in CS2, followed by filtration to remove PbCl2 and evaporation of the solvent, gives As(CNS)3. The same product, a colorless, crystalline solid, can be prepared in benzene solution from AgCNS and ASCI3. 

It combines with hydrogen under the influence of light and heat, and reacts energetically with most of the non-metals forming the respective chlorides. By this method arsenic trichloride may be prepared and this is employed in the preparation of the chlorovinyl arsines (Perkins s method) and diphenyl chloroarsine (Michaelis s method). Sulphur chloride is prepared similarly, and this is employed in the preparation of dichloroethyl sulphide by Guthrie s method. 

Cyanogen was discovered by Wiirtz and prepared for the first time by Berthollet. It was used during the war by the French (October, 1916) both alone and in admixture with arsenic trichloride (" Vivrite ),... 

Ethyl dichloroarsine was prepared by La Coste in 1881 by acting on mercury diethyl with arsenic trichloride ... 

Several compounds obtained by the action of ethylene on arsenic trichloride have also been prepared. Such, for example, is chloroethyl dichloroarsine ... 

In the laboratory, the preparation of the chlorovinyl arsines may be carried out by condensing arsenic trichloride with... 

Preparation of Chlorovinyl Dichloroarsine and Dichlorovinyl Chloroarsine from Trichlorovinyl Arsine 80 gm. trichlorovinyl arsine and 66-2 gm. arsenic trichloride are placed in a thick-walled glass tube which is then sealed in the flame. The tube is placed in an outer tube of steel, covered with asbestos, and the whole heated for 4 hours at 220° to 250° C. After allowing to cool, the glass tube is opened at the end and the oily contents distilled under reduced pressure. The products obtained are as follows ... 

Phenyl dichloroarsine was prepared in 1878 by La Coste and Michaelis by passing the vapours of benzene and arsenic trichloride through a heated tube. The product obtained was impure with the diphenyl compound and could be purified by distillation or crystallisation only with some difficulty. The same workers later studied another method for its preparation. This is more convenient and consists in heating mercury diphenyl to 250° C. with an excess of arsenic trichloride. 

During the war the Allies, in order to obtain rapid production of diphenyl chloroarsine, followed the method of Michaelis, modified by Morgan and Vining. This method consists in preparing triphenyl arsine from chlorobenzene and arsenic trichloride, in the presence of metallic sodium ... 

In order to prepare triphenyl arsine, the arsenic trichloride, the chlorobenzene and the xylene are first mixed in a separate vessel, and of this mixture a half is introduced into the reaction chamber after diluting with more xylene. 

Italian Method. During the war. Professor Contardi proposed a method of preparation much more simple than the American process just described. In studying a new process for manufacturing diphenylamine, he observed that the hydrochloride of this base is completely dissociated into hydrochloric acid and diphenylamine when heated to slightly over 100° C. He studied the possibility of using this reaction to prepare phenarsaane chloride by starting from arsenious oxide and diphenylamine hydrochloride, instead of arsenic trichloride and diphenylamine. The equation of this reaction is as follows ... 

This process differs from the American method more particularly in saving a considerable proportion of the hydrochloric acid (more than two-thirds) and of the arsenious oxide, and also makes it unnecessary to prepare arsenic trichloride. Moreover, all the difficulties attendant on the necessity for utilising or disposing of the large quantities of arsenical products which are invariably obtained in the American process are obviated. 

In one case only has the Fittig reaction been used, namely, in the preparation of tri-w-propylarsine by boiling a mixture of propyl chloride, arsenic trichloride, and sodium ... 

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