Disodium arsenite

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. 

The first step of the process is performed in a separate, dedicated building. The drums of arsenic trioxide are opened in an air-evacuated chamber and automatically dumped into 50% caustic soda. A dust collection system is used. The drums are carefully washed with water, the washwater is added to the reaction mixture, and the dmms are crushed and sold as scrap metal. The intermediate sodium arsenite is obtained as a 25% solution and is stored in large tanks prior to further reaction. In the next step, the 25% sodium arsenite is treated with methyl chloride to produce the disodium salt DSMA (disodium methanearsenate, hexahydrate). This DSMA can be sold as a herbicide however, it is more generally converted to MSMA, which has more favorable application properties [8]. 

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. 

Methyldiiodoarsine has been prepared in a variety of ways treatment of an alcoholic solution of methylarsenic oxide, CH3AsO, with an excess of hydriodic acid,1 passing methylarsine into an alcoholic solution of iodine,2 the action of sulfur dioxide on methylarsenic tetraiodide,3 the action of methyl iodide on arsenic,4 and treatment of a solution of disodium methanearsonate and potassium iodide with hydrochloric acid and sulfur dioxide.6 The following directions are essentially the last method combined with the preparation of the disodium methanearsonate in situ.6,7 The use of an alcoholic medium greatly facilitates the reaction between sodium arsenite and methyl iodide. 

Several acidic solvent systems and types of supports work with varying efficiency (Table 23). Cellulose and silica gel H (with organic binder) allow the movement of arsenite, but arsenate and disodium methanearsonate (DSMA) remain on the origin. DSMA, arsenate and arsenite separate best on thin-layer plates coated with silica gel G (calcium sulphate binder). 

The preparation of this compound has been reported by Jacobs et al. [30] and by Ruddy and Starkey [31], An aqueous solution of 4-nitrobenzenediazonium boro-tetrafluoride (36) is treated with sodium arsenite in the presence of sodium hydroxide and cuprous chloride to give disodium 4-nitrobenzenearsonic acid, which is acidified with hydrochloric acid to afford nitrasone in 71-79% yields [31],... 

Of the more important organic arsenic compounds, the iron-ammonium salt of metylarsonic acid (19), should be mentioned. It is miscible in water and stable in alkaline medium, but is decomposed by acids (acute oral ld,q= 1000 mg/kg). It is prepared by reacting sodium arsenite (20) with methyl iodide (21), and converting the disodium salt obtained (22) into iron-ammonium salt (Quick and Adams, 1922). 0... 

Arsinic acid, dimethyl-. See Cacodylic acid Arsinosolvin. See Sodium arsanilate Arsonic acid, (4-hydroxy-3-nitrophenyl)-. See 4-Hydroxy-3-nitrophenyl arsonic acid Arsonic acid, methyl-, disodium salt. See Disodium methanearsonate Arsonic acid, methyl-, monosodium salt. See Sodium acid methanearsonate Arsonic acid, potassium salt. See Potassium arsenite... 

Sodium arsenate Sodium arsenate, dibasic Sodium arsenate dibasic, anhydrous. See Disodium arsenate Sodium arsenite... 

Sodium merthiolate. See Thimerosal Sodium metaarsenate. See Sodium arsenate Sodium metaarsenite. See Sodium arsenite Sodium metabisulfite CAS 7681-57-4 EINECS/ELINCS 231-673-0 UN NA 2693 (DOT) INS223 E223 Synonyms Disodium disulfite Disodium pyrosulfite Disulfurous acid disodium salt Pyrosulfurous acid disodium salt Sodium bisulfite... 

Bromo-2-nitropropane-1,3-diol Calcium disodium EDTA p-Chloro-m-cresol Dichlorophene Diiodomethyl tolylsulfone Dimethyl oxazolidine Laurtrimonium chloride Pine (Pinus palustris) oil Poly (hexamethylenebiguanide) hydrochloride Sodium 2-mercaptobenzothiazole 2-Thiocyanomethylthiobenzothiazole Tributyltin oxide 2,4,6-Trichlorophenol preservative, timber Zinc arsenite preservative, tissues... 

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