Arsine trichlorovinyl

In general, arsenical compounds have an aggressive action when two of the three valences of the arsenic atom are linked to like atoms or groups and the third to a different atom or radicle. If all the three valences of the arsenic atom are linked to similar atoms or radicles the compound has practically no aggressive action. Thus in the series of chlorovinyl arsines, it has been found that trichlorovinyl arsine has practically no aggressive action compared with chlorovinylchloroarsine or dichlorovinyl chloroarsine ... 

In this mixture trichlorovinyl arsine always predominates and this substance has only a minor interest as a war gas, for its toxicity is low. Chlorovinyl dichloroarsine, which, besides its irritant action on the respiratory passages, also has a vesicant action similar to that of dichloroethyl sulphide, is of much greater importance. The resemblance in the properties of these two substances has been attributed to the presence of the two similar groups ... 

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 ... 

They are sparingly soluble in cold water or in dilute acids, but all—except trichlorovinyl arsine, which is insoluble in alcohol— dissolve readily in alcohol, benzene, kerosene, olive oil, petrol and other organic solvents. 

When a 15% sodium hydroxide solution is employed at temperatures below 37° C., this decomposition takes place quantitatively, and only in the case of chlorovinyl dichloroarsine. This fact may be used for the quantitative determination of /3 chlorovinyl dichloroarsine in presence of dichlorovinyl chloro-arsine and trichlorovinyl arsine (Lewis). 

Chloramine-T. Treatment of dichlorovinyl chloroarsine with an equivalent amount of chloramine-T (CHa=C H4—S02Na=NCl) produces no additive-compound, unlike trichlorovinyl arsine. 

Water. Trichlorovinyl arsine does not react with water and may be distilled in steam without any decomposition. 

Halogens. On adding a solution of bromine in benzene to a benzene solution of trichlorovinyl arsine, cooled in a freezing mixture, small colourless needles separate, melting at 107° C. They consist of trichlorovinyl dibromo arsine (Mann and Pope) ... 

On treating this dibromo compound with hydrogen sulphide, it decomposes to form hydrobromic acid and trichlorovinyl arsine and deposit sulphur ... 

Nitric Acid. Concentrated nitric acid reacts vigorously with trichlorovinyl arsine, and in order to moderate the violence of the reaction, it is advisable to treat a small quantity of trichlorovinyl arsine (not more than 2 gm.) with an equal volume of nitric acid and warm cautiously. On allowing to cool, a colourless crystalline mass is deposited and when this is crystallised from chloroform, small needles, melting at 103° C. are obtained. This substance is trichlorovinyl hydroxyarsonium nitrate. 

Unlike the previous two compounds, trichlorovinyl arsine has no irritant action on the skin or the respiratory organs,... 

Moderate boiling with 15% sodium hydroxide causes the attack of both ]8 chlorovinyl dichloroarsine and dichlorovinyl chloroarsine, but not trichlorovinyl arsine, with formation of sodium arsenite which may be titrated with sodium bromate after acidification. 

Chlorovinyl arsines chlorovinyl dichloroarsine, dichlorovinyl chloroarsine and trichlorovinyl arsine and mixtures of these qv. It is interesting that several authors refer to the many varieties of lewisite. The chlorovinyl dichloroarsine variant qv is said to be typical. 

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