Cacodylic acid Calcium arsenate

Inorganic arsenicals such as arsenic trioxide, sodium arsenite, lead arsenate, calcium arsenate and Paris Green have been used for many years as soil sterilants. Organic arsenical herbicides, in which the organic group is bonded directly to the arsenic atom, have been used extensively for post-emergence control of weeds in cotton. Several of the more important herbicides are sodium cacodylate (monosodium dimethylarsenic acid) and sodium salts of methane arsonic acid. The latter compounds exist in two principal forms the monosodium salt (MSMA) at pH6.4 and the disodium salt (DSMA) at pH10.2. 

Arsenic trioxide finds major use in the preparation of other compounds, notably those used in agricultural applications, The compounds monosodium methylarsonate. disodium methylarsonate, methane arsenic acid (cacodylic acid) are used for weed control, while arsenic acid, H3ASO4, is used as a desiccant for the defoliation of cotton crops, Other compounds once widely used in agriculture are calcium arsenate for control of boll weevils, lead arsenate as a pesticide for fruit crops, and sodium arsenite as a herbicide and for cattle and sheep dip. In some areas, arsenilic acid has been used as a feed additive for swine and poultry. Restrictions on these compounds vary from one country and region to the next. 

Calcium arsenate and lead arsenates (orthoarsenates and more complex arsenates) still are employed for certain cotton insects and codling moth control in apples, as well as for other insect-control purposes. These uses are dwindling, as are the uses of arsenites for soil sterilization. At present, the residue and toxicological properties of the arsenicals in relation to human toxicity and ecological factors are under review by government, scientific, and administrative bodies. The above is true also for organic arsenicals such as cacodylic acid [(CH3)2As(0)0H] and... 

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