Sulfonates, Phosphonates, and Thiophosphonates, Organic

These materials are combustible. Burning them generates highly toxic fumes of phosphorus oxides and (in the case of the thiophosphates) sulfur oxides. Many fire-retardant foams are organophosphate-based and act to lay down a protective layer that excludes oxygen.

Materials in this group are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides.

Variable. The pyrophosphate esters (such as tetraethyl pyrophosphate) are highly toxic. These derivatives form the basis of a group of insecticides. They interfere with normal nerve transmission by inhibiting cholinesterase. These pesticides should be handled with great care (when released to the environment they are rapidly degraded). Other organophosphates behave similarly. Some include extremely toxic war agents sarin, vx, etc.

These compounds are derivatives of sulfonic acid, thiosulfonic acid, and phosphonic acid in which S may substitute for O and organic groups may substitute for H. These compounds are distinct from those in group 13 (esters, including sulfate and phosphate esters) by the presence of organic groups that are directly bonded to the sulfur or phosphorus atom ("non-ester linkage"). Many of these materials are used as plasticizers, insecticides, resin ingredients, war chemical agents, and flame retardants.

Dimefox, fonofos, isofluorphate, leptophos, merphos, sarin.