Tetramethylarsonium iodide

Single oral dose Arsenous oxide Tetramethylarsonium iodide Dimethylarsinic acid Dimethylarsonic acid Arsenocholine Trimethylarsinoxide Arsenobetaine Sodium arsenate... 

Although more than 100 years ago Cahours (35) claimed to have obtained pentamethylarsorane by the reaction of dimethylzinc with tetramethylarsonium iodide, subsequent attempts (55,195) to synthesize pentaalkylarsoranes by the reaction of tetraalkylarsonium salts with organometallic compounds were unsuccessful. However, Mitschke and Schmidbaur (137) have obtained pentamethylarsorane in 80% yield by the following reaction ... 

Trimethylarsine, (CH3)3As.— This compound was first mentioned by Cahours and Hofmann, who stated that it was obtained by the action of potassium hydroxide on the double salt derived from arsenic trichloride and zinc dimethyl. In 1859 Cahours isolated this ansine by distilling tetramethylarsonium iodide or its double salts with potas.sium hydroxide, after having obtained only small yields by treating sodium arsenide with methyl iodide. Auger in 1904 stated that the brown polymer formed when arsenomethane is treated with a trace of hydrogen chloride yields trimethylarsine when distilled in an atmosphere of... 

Tetramethylarsonium iodide, (CH3)4AsI.— The double compound of the iodide with arsenic tri-iodide is formed when powdered arsenic and methyl iodide are heated together at 160° to 200° C. If this reaction is carried out at ordinary temperatures or on the w ater-bath, the principal products are methyldi-iodoarsine and tetramethylarsonium iodide arsenic tri-iodide and a small quantity of cacodyl iodide arc also produced. When methyl iodide is ded to sodium arsenide in an atmosphere of carbon dioxide, the mixture on distillation gives cacodyl and tetramethylarsonium iodide, Cacodyl and methyl iodide react with evolution of heat, yielding the arsonium compound and cacodyl iodide according to the equation ... 

Alloys of arsenic with zinc and cadmium are also capable of giving the arsonium compound when heated at 160° to 180° C. with methyl iodide. It may be produced from its components, trimcthylarsinc and methyl iodide, or by heating methylarsine with an excess of methyl iodide for eight hours in a carbon dioxide atmosphere at 110° C. Arsenomethane, when heated at 100° C. with methyl iodide, ves tetramethylarsonium iodide ajvd methylarsine di-iodide see cyclo-pentamethylpenta-arsine, p. 33. 

Alkyl iodides also react with metal arsenides on heating. Thus tetra-methyldiarsine, trimethylarsine, and tetramethylarsonium iodide are obtained from methyl iodide and sodium arsenide 168). Alkyl iodides and the arsenides of zinc, cadmium, or mercury give mainly compounds of the type (R4As)2Znl4 and R4AsHgl3 219, 220). These reactions are related to those described in Section II, A, 2 and probably to those in Section II, A, 5. 

The search for pentaalkyl and -aryl derivatives of the elements of Group V provides a fascinating story, especially because some rather important discoveries have been made along the way. It began in 1862 when Cahours claimed to have prepared pentamethylarsenic from tetramethylarsonium iodide and dimethyl-zinc. In 1896 Lachman attempted to make pentamethylnitrogen by a similar route at that time chemists imaginations were not restricted by such ideas as the octet rule. Schlenk and Holz did isolate a red compound from the reaction... 

Figure 2. Chromatogram obtained with a solution of arsenate, arsenite, methylarsonic acid, dimethylarsinic acid, arsenobetaine, trimethylarsine oxide, arsenocholine, and tetramethylarsonium iodide (0.5 ng of As each species) in distilled water on a Hamilton PRP-1 re versed-phase column (mobile phase 10 mM 2-hydroxy-5-sulfobenzoic acid) at pH 3.5, injection volume 0.100 cm3, flow rate 1.5 cm3 min-l.

The dialkyl halogenated arsines combine with alkyl halides, the resulting product depending upon experimental conditions, e.g. dimethylbromo-arsine may give rise to tetramethylarsonium mono- or tri-iodide with methyl iodide, whilst metliyl bromide yields trimcthylarsinc dibromide. 

Dimethyliodoarsine shaken 5 days at room temp, with a large excess of mercury and methyl iodide in a sealed tube in the absence of air and light tetramethylarsonium triiodomercury (II). Y 87%. F. e. s. M. M. Baig and W.R. Gullen, Gan. J. Ghem. 39, 420 (1961). 

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