Organothiophosphates or organophosphorothioates are a subclass of
organophosphorus compounds
Organophosphorus compounds 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 ins ...
. Many are used as
pesticides
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampric ...
, some have medical applications, and some are used as oil additives.
They generally have the chemical formula (RO)
3PS,
RO)2P(S)Osup>−, R(RO)
2PS, etc.
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
Antisense therapy is a form of treatment that uses antisense oligonucleotides (ASOs) to target messenger RNA (mRNA). ASOs are capable of altering mRNA expression through a variety of mechanisms, including ribonuclease H mediated decay of the pre-m ...
, e.g., the drugs
fomivirsen
Fomivirsen (brand name Vitravene) is an antisense antiviral drug that was used in the treatment of cytomegalovirus retinitis (CMV) in immunocompromised patients, including those with AIDS. It was administered via intraocular injection.
It was d ...
(Vitravene),
Oblimersen
Oblimersen ( INN, trade name Genasense; also known as Augmerosen and bcl-2 antisense oligodeoxynucleotide G3139) is an antisense oligodeoxyribonucleotide being studied as a possible treatment for several types of cancer, including chronic lymphoc ...
,
Alicaforsen
Alicaforsen (trade name Camligo) is an antisense oligonucleotide therapeutic that targets the messenger RNA for the production of human ICAM-1 receptor and is being developed for the treatment of acute disease flares in moderate to severe Inflamm ...
, and
Mipomersen
Mipomersen (INN; trade name Kynamro) is a drug used to treat homozygous familial hypercholesterolemia and is administered by subcutaneous injection. There is a serious risk of liver damage from this drug and it can only be prescribed in the cont ...
(Kynamro).
Further examples of these include:
*
Diazinon
Diazinon (IUPAC name: ''O'',''O''-Diethyl ''O''- -methyl-6-(propan-2-yl)pyrimidin-2-ylphosphorothioate, INN - Dimpylate), a colorless to dark brown liquid, is a thiophosphoric acid ester developed in 1952 by Ciba-Geigy, a Swiss chemical company ( ...
*
Fenitrothion
Fenitrothion (IUPAC name: ''O'',''O''-dimethyl ''O''-(3-methyl-4-nitrophenyl) phosphorothioate) is a phosphorothioate (organophosphate) insecticide that is inexpensive and widely used worldwide. Trade names include ''Sumithion'', a 94.2% solutio ...
*
Fenthion
Fenthion is an organothiophosphate insecticide, avicide, and acaricide. Like most other organophosphates, its mode of action is via cholinesterase inhibition. Due to its relatively low toxicity towards humans and mammals, fenthion is listed as ...
*
Thiotepa
Thiotepa (INN), sold under the brand name Tepadina, is a medication used to treat cancer.
Thiotepa is an organophosphorus compound with the formula (C2H4N)3PS. It is an analog of ''N'',''N′'',''N′′''-triethylenephosphoramide ( ...
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 and chemical synthesis
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. PS–C bonds can also be formed through many comparable approaches, usually by alkylating a free phosphorous thioate anion or thioic acid.
They are conceptually derived from the inorganic
thiophosphate Thiophosphates (or phosphorothioates, PS) are chemical compounds and anions with the general chemical formula (''x'' = 0, 1, 2, or 3) and related derivatives where organic groups are attached to one or more O or S. Thiophosphates feature tetrahedr ...
s (PO
4−xS). In fact, many are prepared via the intermediacy diorganodithiophosphoric acids, which are prepared by treating
phosphorus pentasulfide
Phosphorus pentasulfide is the inorganic compound with the formula (monomer) or (dimer). 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 d ...
with
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
s:
[
:P2S5 + 4 ROH → 2 (RO)2PS2H + H2S
Dimethyl dithiophosphoric acid and ]diethyl dithiophosphoric acid
Diethyl dithiophosphoric acid, sometimes mistakenly called diethyl dithiophosphate, is the organophosphorus compound with the formula (C2H5O)2PS2H. It is the processor for production of the organophosphate insecticide Terbufos. Although sampl ...
are obtained in this way. The former is a precursor to malathion.
References
External links
* {{MeshName, Organothiophosphorus+Compounds