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.
34-570: DIPAMP is an organophosphorus compound that is used as a ligand in homogeneous catalysis . It is a white solid that dissolves in organic solvents. Work on this compound by W. S. Knowles was recognized with the Nobel Prize in Chemistry . DIPAMP was the basis for one of the first industrial scale asymmetric hydrogenation , the synthesis of the drug L -DOPA . DIPAMP is a C 2 -symmetric diphosphine . Each phosphorus centre, which
68-429: A catalytic alkylant to the former: In the environment, all these phosphorus(V) compounds break down via hydrolysis to eventually afford phosphate and the organic alcohol or amine from which they are derived. Phosphonates are esters of phosphonic acid and have the general formula RP(=O)(OR') 2 . Phosphonates have many technical applications, a well-known member being glyphosate , better known as Roundup. With
102-430: A reverse Arbuzov rearrangement to a dialkylthiophosphinate ester. Compounds with the formula [PR 4 ]X comprise the phosphonium salts . These species are tetrahedral phosphorus(V) compounds. From the commercial perspective, the most important member is tetrakis(hydroxymethyl)phosphonium chloride , [P(CH 2 OH) 4 ]Cl, which is used as a fire retardant in textiles . Approximately 2M kg are produced annually of
136-407: A tripeptide they called bialaphos that inhibits bacteria; it consists of two alanine residues and a unique amino acid that is an analog of glutamate that they named "phosphinothricin". They determined that phosphinothricin irreversibly inhibits glutamine synthetase . Phosphinothricin was first synthesized by scientists at Hoechst in the 1970s as a racemic mixture; this racemic mixture
170-438: A variety of oxidation states , and it is general to classify organophosphorus compounds based on their being derivatives of phosphorus(V) vs phosphorus(III), which are the predominant classes of compounds. In a descriptive but only intermittently used nomenclature, phosphorus compounds are identified by their coordination number σ and their valency λ . In this system, a phosphine is a σ λ compound. Phosphate esters have
204-532: Is 0.021 mg/kg. Glufosinate is a United States Environmental Protection Agency EPA registered chemical. It is also a California registered chemical. It is not banned in the country and it is not a PIC pesticide . There are no exposure limits established by OSHA or the American Conference of Governmental Industrial Hygienists. Glufosinate is not approved for use as an herbicide in Europe; it
238-428: Is a method for the preparation of aminophosphonates. These compounds contain a very inert bond between phosphorus and carbon. Consequently, they hydrolyze to give phosphonic and phosphinic acid derivatives, but not phosphate. Phosphine oxides (designation σ λ ) have the general structure R 3 P=O with formal oxidation state V. Phosphine oxides form hydrogen bonds and some are therefore soluble in water. The P=O bond
272-400: Is a naturally occurring broad-spectrum herbicide produced by several species of Streptomyces soil bacteria. Glufosinate is a non-selective, contact herbicide, with some systemic action. Plants may also metabolize bialaphos and phosalacine , other naturally occurring herbicides, directly into glufosinate. The compound irreversibly inhibits glutamine synthetase , an enzyme necessary for
306-481: Is applied to young plants during early development for full effectiveness. It is sold in formulations under brands including Basta, Rely, Finale, Challenge and Liberty. Glufosinate is typically used in three situations as an herbicide: Glufosinate also has shown to provide some protection against various plant diseases, as it also acts to kill fungi and bacteria on contact. Genetically modified crops resistant to glufosinate were created by genetically engineering
340-478: Is called glufosinate and is the commercially relevant version of the chemical. In the late 1980s scientists discovered enzymes in these Streptomyces species that selectively inactivate free phosphinothricin; the gene encoding the enzyme that was isolated from Streptomyces hygroscopicus was called the "bialaphos resistance" or "bar" gene, and the gene encoding the enzyme in Streptomyces viridochromogenes
374-441: Is known, being derived from P(C 6 H 5 ) 4 by reaction with phenyllithium . Phosphorus ylides are unsaturated phosphoranes, known as Wittig reagents , e.g. CH 2 P(C 6 H 5 ) 3 . These compounds feature tetrahedral phosphorus(V) and are considered relatives of phosphine oxides. They also are derived from phosphonium salts, but by deprotonation not alkylation. Phosphites, sometimes called phosphite esters , have
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#1732794398594408-401: Is pyramidal, bears three different substituents - anisyl , phenyl, and the ethylene group. The ligand therefore exists as the enantiomeric ( R , R ) and ( S , S ) pair, as well as the achiral meso isomer. DIPAMP was originally prepared by an oxidative coupling, starting from anisyl(phenyl)(methyl)phosphine. Organophosphorus compound Phosphorus, like nitrogen , is in group 15 of
442-469: Is very polar with a dipole moment of 4.51 D for triphenylphosphine oxide . Compounds related to phosphine oxides include phosphine imides (R 3 PNR') and related chalcogenides (R 3 PE, where E = S , Se , Te ). These compounds are some of the most thermally stable organophosphorus compounds. In general, they are less basic than the corresponding phosphine oxides, which can adduce to thiophosphoryl halides: Some phosphorus sulfides can undergo
476-572: The Wittig reaction and as supporting phosphine ligands in homogeneous catalysis . Their nucleophilicity is evidenced by their reactions with alkyl halides to give phosphonium salts . Phosphines are nucleophilic catalysts in organic synthesis , e.g. the Rauhut–Currier reaction and Baylis-Hillman reaction . Phosphines are reducing agents , as illustrated in the Staudinger reduction for
510-425: The bar or pat genes from streptomyces into the relevant crop seeds. In 1995 the first glufosinate-resistant crop, canola, was brought to market, and it was followed by corn in 1997, cotton in 2004, and soybeans in 2011. Phosphinothricin is a glutamine synthetase inhibitor that binds to the glutamate site. Glufosinate-treated plants die due to a buildup of ammonia in the thylakoid lumen, leading to
544-513: The anti-cancer drug cyclophosphamide . Also derivatives containing the thiophosphoryl group (P=S) include the pesticide malathion . The organophosphates prepared on the largest scale are the zinc dithiophosphates , as additives for motor oil. Several million kilograms of this coordination complex are produced annually by the reaction of phosphorus pentasulfide with alcohols. Phosphoryl thioates are thermodynamically much stabler than thiophosphates, which can rearrange at high temperature or with
578-493: The chemical can be passed to humans through animals who are fed contaminated straw. Flour processed from wheat grain that contained traces of glufosinate was found to retain 10-100% of the chemicals' residues. The herbicide is also persistent; it has been found to be prevalent in spinach, radishes, wheat and carrots that were planted 120 days after the treatment of the herbicide. Its persistent nature can also be observed by its half-life which varies from 3 to 70 days depending on
612-640: The chloride and the related sulfate. They are generated by the reaction of phosphine with formaldehyde in the presence of the mineral acid: A variety of phosphonium salts can be prepared by alkylation and arylation of organophosphines: The methylation of triphenylphosphine is the first step in the preparation of the Wittig reagent. The parent phosphorane (σ λ ) is PH 5 , which is unknown. Related compounds containing both halide and organic substituents on phosphorus are fairly common. Those with five organic substituents are rare, although P(C 6 H 5 ) 5
646-495: The commercial perspective, the most important phosphine is triphenylphosphine , several million kilograms being produced annually. It is prepared from the reaction of chlorobenzene , PCl 3 , and sodium. Phosphines of a more specialized nature are usually prepared by other routes. Phosphorus halides undergo nucleophilic displacement by organometallic reagents such as Grignard reagents . Organophosphines are nucleophiles and ligands . Two major applications are as reagents in
680-426: The compound phosphorine , one carbon atom in benzene is replaced by phosphorus. Species of this type are relatively rare but for that reason are of interest to researchers. A general method for the synthesis of phosphaalkenes is by 1,2-elimination of suitable precursors, initiated thermally or by base such as DBU , DABCO , or triethylamine : Thermolysis of Me 2 PH generates CH 2 =PMe, an unstable species in
714-421: The condensed phase. Compounds where phosphorus exists in a formal oxidation state of less than III are uncommon, but examples are known for each class. Organophosphorus(0) species are debatably illustrated by the carbene adducts, [P(NHC)] 2 , where NHC is an N-heterocyclic carbene . With the formulae (RP) n and (R 2 P) 2 , respectively, compounds of phosphorus(I) and (II) are generated by reduction of
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#1732794398594748-614: The conversion of organic azides to amines and in the Mitsunobu reaction for converting alcohols into esters. In these processes, the phosphine is oxidized to phosphorus(V). Phosphines have also been found to reduce activated carbonyl groups, for instance the reduction of an α-keto ester to an α-hydroxy ester. Compounds with carbon phosphorus(III) multiple bonds are called phosphaalkenes (R 2 C=PR) and phosphaalkynes (RC≡P). They are similar in structure, but not in reactivity, to imines (R 2 C=NR) and nitriles (RC≡N), respectively. In
782-644: The corresponding phosphonous and phosphinous chlorides ((PCl 2 R') and (PClR' 2 ) , respectively). The latter are produced by reaction of a phosphorus trichloride with a poor metal -alkyl complex, e.g. organomercury , organolead , or a mixed lithium - organoaluminum compound. The parent compound of the phosphines is PH 3 , called phosphine in the US and British Commonwealth, but phosphane elsewhere. Replacement of one or more hydrogen centers by an organic substituents (alkyl, aryl), gives PH 3−x R x , an organophosphine, generally referred to as phosphines. From
816-465: The formula (HO) 2 P(O)CH 2 NHCH 2 CO 2 H, this derivative of glycine is one of the most widely used herbicides. Bisphosphonates are a class of drugs to treat osteoporosis . The nerve gas agent sarin , containing both C–P and F–P bonds, is a phosphonate. Phosphinates feature two P–C bonds, with the general formula R 2 P(=O)(OR'). A commercially significant member is the herbicide glufosinate . Similar to glyphosate mentioned above, it has
850-511: The general structure P(=O)(OR) 3 feature P(V). Such species are of technological importance as flame retardant agents, and plasticizers . Lacking a P−C bond, these compounds are in the technical sense not organophosphorus compounds but esters of phosphoric acid. Many derivatives are found in nature, such as phosphatidylcholine . Phosphate ester are synthesized by alcoholysis of phosphorus oxychloride. A variety of mixed amido-alkoxo derivatives are known, one medically significant example being
884-617: The general structure P(OR) 3 with oxidation state +3. Such species arise from the alcoholysis of phosphorus trichloride: The reaction is general, thus a vast number of such species are known. Phosphites are employed in the Perkow reaction and the Michaelis–Arbuzov reaction . They also serve as ligands in organometallic chemistry. Intermediate between phosphites and phosphines are phosphonites (P(OR) 2 R') and phosphinite (P(OR)R' 2 ). Such species arise via alcoholysis reactions of
918-495: The periodic table, and thus phosphorus compounds and nitrogen compounds have many similar properties. The definition of organophosphorus compounds is variable, which can lead to confusion. In industrial and environmental chemistry, an organophosphorus compound need contain only an organic substituent , but need not have a direct phosphorus-carbon (P-C) bond. Thus a large proportion of pesticides (e.g., malathion ), are often included in this class of compounds. Phosphorus can adopt
952-555: The production of glutamine and for ammonia detoxification, giving it antibacterial , antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis and resulting in plant death. In the 1960s and early 1970s, scientists at University of Tübingen and at the Meiji Seika Kaisha Company independently discovered that species of Streptomyces bacteria produce
986-528: The related organophosphorus(III) chlorides: Diphosphenes , with the formula R 2 P 2 , formally contain phosphorus-phosphorus double bonds. These phosphorus(I) species are rare but are stable provided that the organic substituents are large enough to prevent catenation . Bulky substituents also stabilize phosphorus radicals . Many mixed-valence compounds are known, e.g. the cage P 7 (CH 3 ) 3 . Glufosinate Glufosinate (also known as phosphinothricin and often sold as an ammonium salt )
1020-407: The soil type and organic matter content. Residues can remain in frozen food for up to two years and the chemical is not easily destroyed by cooking the food item in boiling water. The EPA classifies the chemical as 'persistent' and 'mobile' based on its lack of degradation and ease of transport through soil. A study revealed the presence of circulating PAGMF in women with and without pregnancy, paving
1054-607: The structure CH 3 P(O)(OH)CH 2 CH 2 CH(NH 2 )CO 2 H. The Michaelis–Arbuzov reaction is the main method for the synthesis of these compounds. For example, dimethylmethylphosphonate (see figure above) arises from the rearrangement of trimethylphosphite , which is catalyzed by methyl iodide . In the Horner–Wadsworth–Emmons reaction and the Seyferth–Gilbert homologation , phosphonates are used in reactions with carbonyl compounds. The Kabachnik–Fields reaction
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1088-469: The uncoupling of photophosphorylation . The uncoupling of photophosphorylation causes the production of reactive oxygen species , lipid peroxidation , and membrane destruction. Elevated levels of ammonia are detectable within one hour after application of phosphinothricin. As glufosinate is often used as a pre-harvest desiccant , it can be found in foods that humans ingest. Such foods include potatoes, peas, beans, corn, wheat, and barley. In addition,
1122-629: The way for a new field in reproductive toxicology including nutrition and utero-placental toxicities There are no exposure limits established by the Occupational Safety & Health Administration or the American Conference of Governmental Industrial Hygienists . The WHO/FAO recommended acceptable daily intake (ADI) for glufosinate is 0.02 mg/kg. The European Food Safety Authority has set an ADI of 0.021 mg/kg. The Acute reference dose (ARfD) for child-bearing women
1156-495: Was called " phosphinothricin acetyltransferase " or "pat". The two genes and their proteins have 80% homology on the DNA level and 86% amino acid homology, and are each 158 amino acids long. Glufosinate is a broad-spectrum herbicide that is used to control important weeds such as morning glories , hemp sesbania ( Sesbania bispinosa ), Pennsylvania smartweed ( Polygonum pensylvanicum ) and yellow nutsedge similar to glyphosate . It
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