Organophosphate

An organophosphate (sometimes abbreviated OP) or phosphate ester is the general name for esters of phosphoric acid. Many of the most important biochemicals are organophosphates, including DNA and RNA, as well as many of the cofactors essential for life. Organophosphates are the basis of many insecticides, herbicides, and nerve agents. The United States Environmental Protection Agency lists organophosphates as very highly acutely toxic to bees, wildlife, and humans. Recent studies suggest a possible link to adverse effects in the neurobehavioral development of fetuses and children, even at very low levels of exposure. Organophosphates are widely used as solvents, plasticizers, and EP additives.

Organophosphates are widely employed both in natural and synthetic applications because of the ease with which organic groups can be linked together.

The phosphate esters bearing OH groups are acidic and partially deprotonated in aqueous solution. For example, DNA and RNA are polymers of the type [PO₂(OR)(OR')⁻]_n. Polyphosphates also form esters; an important example of an ester of a polyphosphate is ATP, which is the monoester of triphosphoric acid (H₅P₃O₁₀).

Alcohols can be detached from phosphate esters by hydrolysis, which is the reverse of the above reactions. For this reason, phosphate esters are common carriers of organic groups in biosynthesis.

In health, agriculture, and government, the word "organophosphates" refers to a group of insecticides or nerve agents acting on the enzyme acetylcholinesterase (the pesticide group carbamates also act on this enzyme, but through a different mechanism). The term is used often to describe virtually any organic phosphorus(V)-containing compound, especially when dealing with neurotoxic compounds. Many of the so-called organophosphates contain C-P bonds. For instance, sarin is O-isopropyl methylphosphonofluoridate, which is formally derived from phosphorous acid (HP(O)(OH)₂), not phosphoric acid (P(O)(OH)₃). Also, many compounds which are derivatives of phosphinic acid are used as neurotoxic organophosphates.

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