Aromatic Arsines

This compound may be obtained by treating an acetone solution of the tertiary amine (i molecule) with chloramine-T (i molecule) and boiling for 20 minutes. The product is filtered, the filtrate evaporated to dryness and the residue crystallised several times from ether. Colourless plates, melting at 124° C. 

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

The aromatic arsines were first employed as war gases in July, 1917, by the Germans, and their use undoubtedly marked a considerable step in the progress of the chemical arm. 

These arsines differ from those of the aliphatic series which have just been described, by their physical and chemical properties, and by their method of employment, as well as by their biological action. They are solids or liquids with high boiling points, have very low vapour tensions, are quite resistant to heating and are only oxidised by atmospheric oxygen with difficulty. 

In order to obtain them sub-divided in the air they are employed dissolved in other war gases, or are filled into special containers so that they surround the bursting charge, or else are mixed with substances whose temperature of combustion is sufficiently high to cause the arsines to form a cloud (candles, generators, etc.). By- these means disperse systems (aerosols) are formed in which the dispersed phase consists of extremely minute particles of the arsine. These remain suspended in the air for a considerable time and are not filtered out by activated carbon. 

---

In the series of aromatic arsines there is a great difference in aggressive action between triphenyl arsine, phenyl dichloroarsine and diphenyl chloroarsine. 

It has been found that while the aliphatic arsines and phenyl carbylamine chloride produce a similar turbidity at high concentration (4%), other substances such as mono-, di- and tri-chloromethyl chloroformates, chloropicrin, benzyl bromide, acrolein, the aromatic arsines, thiodiglycol, etc., do not react. 

Of these, the aromatic arsines were very largely used during the war, especially diphenyl chloroarsine. The aggressive action of these aromatic arsines, unlike that of all the compounds... 

Most of the aliphatic and aromatic arsines employed during the war of 1914-18 were substances which had been known for some time. The only new substances are the chlorovinyl arsines and phenarsazine chloride, of whose practical efficiency somewhat conflicting opinions are still held. 

These substances, though more powerfully toxic than the aromatic arsines, are of minor importance because of their rapid diffusion in the air without forming aerosols. 

Even the chlorovinyl arsines, although they are easily prepared, do not seem to be sufficiently aggressive in their action to replace the aromatic arsines. According to several authorities, experiments on the methods of military application of the chlorovinyl arsines have been abandoned even in America. 

The study of the heterocyclic arsines i.e., those containing the atom of arsenic in the nucleus) may be said to have commenced only during the war of 1914-18 and led to the discovery of substances whose military value is equal, or according to some authorities superior, to that of the aromatic arsines. Among these substances Adamsite has claimed most interest, particularly because of the simplicity of its method of preparation. 

There are six types of tertiary aromatic arsines known, if those containing aliphatic radicals are also included ArjAs, ArAr As, ArgAlkAs, ArAlk As, ArAr AlkAs, ArAlkAlk As. For the tyj>e ArjAs, theFittig reaction forms thebasisof a method of preparation, aryl halides and arsenic trihalides reacting in ether or benzene solution in th< ))re-senee of sodium as follows ... 

The halogenated aromatic arsines combine additively with dry chlorine or bromine, yielding diarylatsine trihalides ... 

AROMATIC ARSINE OXIDES, HYDROXIDES, AND SULPHIDES. 131 In some cases dihydroxides, when heated, eliminate water RsAs(0H)j=RsAs0+H30... 

Although six types of tertiary aromatic arsines are known, only three varieties of corresponding stibines have been described to date, namely, ArjSb, ArsAlkSb and ArAlkaSb. The most numerous compounds are those of the type ArgSb, and their preparation is effected by the following methods —... 

Inspired by a daim in the patent literature ]27], Sheldon et al. identified di-n-butyl-phenylarsine as a highly active catalyst for the epoxidation of cydohexene as the substrate, and with 60% hydrogen peroxide in TFE as the solvent [28]. Among a series of purely aromatic arsines, electron-rich ones (such as Ph3As) were found to be... 

---