Methylarsonic acid

As(ONa), -I- CH,I — [CH,As(ONa)jI] CH,AsO(ONa), — CH,AsO(OH), unstable product losing sodium iodide to form disodium methylarsonate, which on acidification liberates methylarsonic acid. Note that this synthesis is limited to alkylarsonic acids, whereas the Bart synthesis (p. 312) is limited to aiy larsonic acids. 

The process may now be continued. Methylarsonic acid, when reduced by sulphur dioxide in concentrated hydrochloric acid, gives dichloromethylarsine, CHjAsCl. If this arsine is added to aqueous sodium hydroxide, it is hydrolysed to the weakly acidic methylarsenous acid, CH3As(OH)j, which in the alkali... 

MSMA [2163-80-6] monosodium salt of methylarsonic acid CH3ASO3 -Na... 

AMA cacodyhc acid [75-60-5] ammonium methylarsonic acid dimethyl arsinic acid C2H2ASO2... 

The F nmr spectrum of this compound gives only one signal over a wide range of temperatures, a result attributed to Berry pseudorotation (144). No alkyl- or aryltetrabromoarsorane has been reported. There is, however, an early report on the preparation of tetraiodomethylarsorane from methylarsonic acid and hydriodic acid (145). 

In 1933 Challenger et al. discovered that trimethylarsine was synthesized from inorganic arsenic compounds by molds (93). Recently, McBride and Wolfe (94), have reported the synthesis of dimethylarsine from arsenate by cell extracts of the methanogenic bacterium M. O. H. Methylcobalamin is the alkylating coenzyme for this synthesis which requires reduction of arsenate to arsenite, methylation of arsenite to methylarsonic acid, reduction and methylation of methylarsonic acid to dimethylarsinic acid, and finally a four electron reduction of dimethylarsinic acid to dimethylarsine (Fig. 13). 

When Schwarzenbach et al. used chloromethylphosphonic acid to phosphonomethylate amines, they noted (128, p. 1185) how slowly it reacts. The slowness is presumably due to the staggered conformation of the chloromethyl and phosphono groups, so that one of the oxygen atoms must be in the Cl—C—C plane and must hinder the approach of any nucleophile that could displace the chloride. They overcame this with long reaction times and high temperatures. In view of the lability of C—As bonds, this approach is not available with 1-haloalkylarsonic acids. Indeed, arsonochloroacetic, chloromethylarsonic, and dibromo-methylarsonic acids (129) proved inert to substitution. 

Methylarsonic acid [124-58-3] M 137.9, m 161°. Crystd from absolute EtOH,... 

Wildfang, E., Zakharyan, R.A. and Aposhian, H.V. (1998) Enzymatic methylation of arsenic compounds VI. Characterization of hamster liver arsenite and methylarsonic acid methyltransferase activities in vitro. Toxicology and Applied Pharmacology, 152(2), 366-75. 

Byrne et al. (1995), in a study of arsenic-accumulating mycorrhizal and saprophytic mushrooms, identified and confirmed the presence of methylarsonic acid, arsenite, arsenate, dimethylarsinic acid and arsenobetaine. This was the first reported occurrence of arsenobetaine in terrestrial biota. In a more extensive investigation (Svlejkovec et al., 1997) in which 50 mushroom species from five countries, across three continents, were studied, arsenocholine and tetramethylarsonium ion, (CH3)4As+, were found in addition to the other arsenic species... 

In a departure from the usual study of arsenic metabolites in mammals, Kuehnelt et at. (1997) found mainly arsenate, arsenite and dimethylarsinic acid, and traces of methylarsonic acid and arsenobetaine in ants living close to an arsenic smelter. The low total arsenic levels, about 12.6mg kg-1, in the ants was suggested as indicative of a protective mechanism which prevents the uptake of arsenic from the high ambient levels. The resistance of micro-organisms to arsenic compounds has been reviewed (Cervantes et at., 1994). 

Dimethyl arsenic acid yields predominantly dimethylarsine, while methylarsonic acid yields predominantly methylarsine and trimethylarsine oxide yields predominantly trimethylarsine. 

Bermejo-Barrera, P., Moreda-Pineiro, J., Moreda-Pineiro, A., Bermejo-Barrera, A. Selective medium reactions for the arsenic(III), arsenic(V), dimethylarsonic acid and mono-methylarsonic acid determination in waters by hydride generation online electrothermal atomic absorption spectrometry with in situ preconcentration on Zr-coated graphite tubes. Anal. Chim. Acta 374, 231-240 (1998)... 

Liu, Z., Sanchez, M.A., Jiang, X., Boles, E., Landfear, S.M., Rosen, B.P. (2006). Mammalian glucose permease GLUTl facilitates transport of arsenic trioxide and methylarsonous acid. Biochem. Biophys. Res. Commun. 351 424-30. 

Ipolyi I. and Fodor P. (2000) Development of analytical systems for the simultaneous determination of the speciation of arsenic As(III), methylarsonic acid, dimethylarsinic acid, As(V) and selenium Se(IV), Se(VI). Analyt. Chim. Acta 413, 13-23. 

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