Chemical Properties
White solid. Very solu-
ble in water.
General Description
Odorless colorless solid. Solution may be red or green. Solid may float or sink in water; solid and solution mix with water.
Air & Water Reactions
Water soluble.
Reactivity Profile
Sodium methylarsonate is decomposed by strong oxidizers and reducers.
Health Hazard
Subacute poisoning by arsenicals causes salty taste, burning in throat and stomach, and intestinal pain. Acute toxicity indicated by headache, vomiting, stupor, convulsions, paralysis. About 1 ounce to 1 pound must be taken to cause these symptoms.
Fire Hazard
Special Hazards of Combustion Products: Toxic gases may be generated in fires.
Potential Exposure
Those exposed to this organometallic, selective pesticide used for postemergence control of grasses, sedges, and weeds.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Shipping
UN2994 Arsenical pesticides, liquid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials. UN3280 Organoarsenic compound, liquid, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required, Potential Inhalation Hazard (Special Provision 5).
Incompatibilities
Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Incompatible with reducing agents
Description
Monosodium methylarsonate is a herbicide that is not widely approved for use in the developed world due to its toxicity. As well as being highly toxic it is also a known skin, eye and inhalation irritant. It is highly soluble in water and considered to be persistent in soils. Monosodium methylarsonate is moderately toxic to fish, algae and honeybees and slightly less toxic to birds.
Waste Disposal
Disposal of unused product must be undertaken by qualified personnel who are knowledgeable in all applicable regulations and follow all pertinent safety precautions including the use of appropriate protective equipment. For proper handling and disposal, always comply with federal, state, and local regulations.
Production Methods
Monosodium methylarsonate is commercially produced by reacting methylarsonic acid with sodium hydroxide. The process begins with the synthesis of methylarsonic acid, typically derived from the controlled oxidation of methylarsine or trimethylarsine oxide. This acid is then neutralised with sodium hydroxide to yield the monosodium salt. The reaction is conducted in aqueous solution under mild conditions, followed by concentration and crystallization to obtain the solid product.
Trade name
WEED-BROOM® (DSMA+Bomacil+2,4-D); WEEDE-RAD®; WEED-S-RAD®; WEED HOE®
Mechanism of action
Selective, contact herbicide, phytotoxic
