Organothiophosphate

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Organothiophosphates or organophosphorothioates are a subclass of organophosphorus compounds and of thiophosphate compounds. They are the organic compounds that contain a phosphate group in which one or more oxygen atoms is substituted by sulfur. Many are used as pesticides, some have medical applications, and some are used as oil additives. [1] They generally have the chemical formula (RO)3PS, [(RO)2P(S)O]−, R(RO)2PS, etc.

Contents

Oligonucleotide phosphorothioates (OPS) are modified oligonucleotides where one of the oxygen atoms in the phosphate moiety is replaced by sulfur. These compounds are the basis of antisense therapy, e.g., the drugs fomivirsen (Vitravene), oblimersen, alicaforsen, and mipomersen (Kynamro). [2]

Further examples of these include:

Variants with P=S double bonds were developed as insecticides because of their reduced mammalian toxicity. The phosphorothioate P=S bond is converted to the toxic P=O bond in the target insect. Similar oxidative conversion in mammals is slower, conferring lower toxicity in mammals.

Structure, synthesis, and reactions

Generally these compounds feature tetrahedral phosphorus(V) centers. Classically, thiophosphates would include a P=S double bond as illustrated by malathion. The terminology is used loosely and thiophosphates include P-S single bonds as illustrated by the drug amifostine. P–S single bonds can be generated through a variety of approaches, starting from thiols, disulfides, sulfinic acids as sulfur sources and various P(III) and P(V) coupling partners. [3] PS–C bonds can also be formed through many comparable approaches, usually by alkylating a free phosphorus-thioate anion or thioic acid. [4]

They are conceptually derived from the inorganic thiophosphates (PO4−xS3−
x). In fact, many are prepared via the intermediacy diorganodithiophosphoric acids, which are prepared by treating phosphorus pentasulfide with alcohols: [1]

P2S5 + 4 ROH → 2 (RO)2PS2H + H2S

Dimethyl dithiophosphoric acid and diethyl dithiophosphoric acid are obtained in this way. The former is a precursor to malathion.

In the Michalski reaction, a thiophosphate reacts with chlorine gas to give a diorganylphosphorylsulfenyl chloride: [5]

(RO)3PS + Cl2 → (RO)2P(O)SCl + RCl

Related Research Articles

<span class="mw-page-title-main">Phosphorus</span> Chemical element with atomic number 15 (P)

Phosphorus is a chemical element; it has symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth. It has a concentration in the Earth's crust of about 0.1%, less abundant than hydrogen but more than manganese. In minerals, phosphorus generally occurs as phosphate.

<span class="mw-page-title-main">Phosphate</span> Anion, salt, functional group or ester derived from a phosphoric acid

In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid, a.k.a. phosphoric acid H3PO4.

<span class="mw-page-title-main">Parathion</span> Chemical compound

Parathion, also called parathion-ethyl or diethyl parathion and locally known as "Folidol", is an organophosphate insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, including humans, so its use has been banned or restricted in most countries. The basic structure is shared by parathion methyl.

<span class="mw-page-title-main">Organophosphate</span> Organic compounds with the structure O=P(OR)3

In organic chemistry, organophosphates are a class of organophosphorus compounds with the general structure O=P(OR)3, a central phosphate molecule with alkyl or aromatic substituents. They can be considered as esters of phosphoric acid. Organophosphates are best known for their use as pesticides.

Demeton-S-methyl is an organic compound with the molecular formula C6H15O3PS2. It was used as an organothiophosphate acaricide and organothiophosphate insecticide. It is flammable. With prolonged storage, Demeton-S-methyl becomes more toxic due to formation of a sulfonium derivative which has greater affinity to the human form of the acetylcholinesterase enzyme, and this may present a hazard in agricultural use.

<span class="mw-page-title-main">Phosphorus trichloride</span> Chemical compound

Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic and reacts readily with water to release hydrogen chloride.

<span class="mw-page-title-main">Sodium dithiophosphate</span> Chemical compound

Sodium dithiophosphate is the salt with the formula Na3PS2O2. It is usually supplied as the hydrated solid or as an aqueous solution together with other thiophosphates such as sodium monothiophosphate and sodium trithiophosphate. It is a colorless compound, but commercial samples can appear dark owing to the presence of impurities. It is used to facilitate the isolation of molybdenum from its ores.

<span class="mw-page-title-main">Phosphorus pentasulfide</span> Chemical compound

Phosphorus pentasulfide is the inorganic compound with the formula P2S5 (empirical) or P4S10 (molecular). This yellow solid is the one of two phosphorus sulfides of commercial value. Samples often appear greenish-gray due to impurities. It is soluble in carbon disulfide but reacts with many other solvents such as alcohols, DMSO, and DMF.

Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective insecticides, although some are extremely toxic to humans, including sarin and VX nerve agents.

<span class="mw-page-title-main">Thiophosphoryl chloride</span> Chemical compound

Thiophosphoryl chloride is an inorganic compound with the chemical formula PSCl3. It is a colorless pungent smelling liquid that fumes in air. It is synthesized from phosphorus chloride and used to thiophosphorylate organic compounds, such as to produce insecticides.

Thiophosphates (or phosphorothioates, PS) are chemical compounds and anions with the general chemical formula PS
4−xO3−
x (x = 0, 1, 2, or 3) and related derivatives where organic groups are attached to one or more O or S. Thiophosphates feature tetrahedral phosphorus(V) centers.

<span class="mw-page-title-main">Chlorethoxyfos</span> Chemical compound

Chlorethoxyfos is an organophosphate acetylcholinesterase inhibitor used as an insecticide. It is registered for the control of corn rootworms, wireworms, cutworms, seed corn maggot, white grubs and symphylans on corn. The insecticide is sold under the trade name Fortress by E.I. du Pont de Nemours & Company.

<span class="mw-page-title-main">Tetraethyl pyrophosphate</span> Chemical compound

Tetraethyl pyrophosphate, abbreviated TEPP, is an organophosphate compound with the formula [(C2H5O)2P(O)]2O. It is the tetraethyl derivative of pyrophosphate (P2O74-). It is a colorless oil that solidifies near room temperature. It is used as an insecticide. The compound hydrolyzes rapidly.

<span class="mw-page-title-main">Cyanophos</span> Chemical compound

Cyanophos is a cholinesterase inhibitor used as an insecticide and avicide; for example, against rice stem borers and house flies. It is part of the chemical class of organophosphorus compounds, and is a yellow to reddish-yellow transparent liquid.

<span class="mw-page-title-main">Endothion</span> Chemical compound

Endothion is an organic compound used as an insecticide and acaricides. It is part of the chemical class of organophosphorus compounds. It is generally described as white crystals with a slight odor. It is used as an insecticide, but not sold in the United States or Canada.

<span class="mw-page-title-main">Methylphosphonyl dichloride</span> Chemical compound

Methylphosphonyl dichloride (DC) or dichloro is an organophosphorus compound. It has commercial application in oligonucleotide synthesis, but is most notable as being a precursor to several chemical weapons agents. It is a white crystalline solid that melts slightly above room temperature.

<span class="mw-page-title-main">Dimethyl dithiophosphoric acid</span> Chemical compound

Dimethyl dithiophosphoric acid is the organophosphorus compound with the formula (CH3O)2PS2H. It is the processor for production of the organothiophosphate insecticide Malathion. Although samples can appear dark, the compound is a colorless, distillable liquid.

<span class="mw-page-title-main">Diethylphosphite</span> Chemical compound

Diethyl phosphite is the organophosphorus compound with the formula (C2H5O)2P(O)H. It is a popular reagent for generating other organophosphorus compounds, exploiting the high reactivity of the P-H bond. Diethyl phosphite is a colorless liquid. The molecule is tetrahedral.

<span class="mw-page-title-main">Dimethylphosphite</span> Chemical compound

Dimethylphosphite is an organophosphorus compound with the formula (CH3O)2P(O)H, known as dimethyl hydrogen phosphite (DMHP). Dimethylphosphite, is a minor tautomer of the phosphorus(V) derivative. It is a reagent for generating other organophosphorus compounds, exploiting the high reactivity of the P-H bond. The molecule is tetrahedral. It is a colorless liquid. The compounds can be prepared by methanolysis of phosphorus trichloride or by heating diethylphosphite in methanol.

<span class="mw-page-title-main">Cadusafos</span> Thiosulfate insecticide against nematodes

Cadusafos is a chemical insecticide and nematicide often used against parasitic nematode populations. The compound acts as a acetylcholinesterase inhibitor. It belongs the chemical class of synthetic organic thiophosphates and it is a volatile and persistent clear liquid. It is used on food crops such as tomatoes, bananas and chickpeas. It is currently not approved by the European Commission for use in the EU. Exposure can occur through inhalation, ingestion or contact with the skin. The compound is highly toxic to nematodes, earthworms and birds but poses no carcinogenic risk to humans.

References

  1. 1 2 Svara, Jürgen; Weferling, Norbert; Hofmann, Thomas (2006). "Phosphorus Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a19_545.pub2. ISBN   3527306730.
  2. ↑ Kurreck, Jens (2003). "Antisense technologies. Improvement through novel chemical modifications". European Journal of Biochemistry. 270 (8): 1628–1644. doi:10.1046/j.1432-1033.2003.03555.x. PMID   12694176.
  3. ↑ Jones, David J.; O'Leary, Eileen M.; O'Sullivan, Timothy P. (2020-07-29). "Modern Synthetic Approaches to Phosphorus-Sulfur Bond Formation in Organophosphorus Compounds". Advanced Synthesis & Catalysis. 362 (14): 2801–2846. doi:10.1002/adsc.202000458. hdl: 10468/10373 . ISSN   1615-4150. S2CID   225475935.
  4. ↑ Jones, David J.; O'Leary, Eileen M.; O'Sullivan, Timothy P. (2018-12-05). "Synthesis and application of phosphonothioates, phosphonodithioates, phosphorothioates, phosphinothioates and related compounds". Tetrahedron Letters. 59 (49): 4279–4292. doi:10.1016/j.tetlet.2018.10.058. hdl: 10468/7209 . ISSN   0040-4039. S2CID   105852959.
  5. ↑ Almasi, Lucreţia (1971). "The Sulfur–Phosphorus Bond". In Senning, Alexander (ed.). Sulfur in Organic and Inorganic Chemistry. Vol. 1. New York: Marcel Dekker. p. 73. ISBN   0-8247-1615-9. LCCN   70-154612.
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