Phosphonates
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In
organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...
, phosphonates or phosphonic acids are
organophosphorus compound 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 in ...
s containing
groups A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...
(where R =
alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloalk ...
,
aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as ...
, or just
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
). Phosphonic acids, typically handled as salts, are generally nonvolatile solids that are poorly
soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...
in
organic solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...
s, but soluble in water and common
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. Many commercially important compounds are phosphonates, including
glyphosate Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum Herbicide, systemic herbicide and Crop desiccation, crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plan ...
(the active molecule of the herbicide
Roundup A roundup is a systematic gathering together of people or things. Roundup, Round Up or Round-up may also refer to: Agriculture * A muster (livestock) (AU/NZ) or a roundup (US/CA) is the process of gathering livestock. * Roundup (herbicide), a M ...
), and ethephon, a widely used plant growth regulator.
Bisphosphonates Bisphosphonates are a class of drugs that prevent the loss of bone density, used to treat osteoporosis and similar diseases. They are the most commonly prescribed drugs used to treat osteoporosis. They are called bisphosphonates because they h ...
are popular drugs for treatment of
osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...
.Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2008. . In
biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
and medicinal chemistry, phosphonate groups are used as stable bioisoteres for phosphate, such as in the antiviral nucleotide analog, Tenofovir, one of the cornerstones of anti-
HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...
therapy. And there is an indication that phosphonate derivatives are "promising ligands for
nuclear medicine Nuclear medicine or nucleology is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. Nuclear imaging, in a sense, is "radiology done inside out" because it records radiation emitting ...
."


Basic properties

Phosphonates feature tetrahedral phosphorus centers. They are structurally closely related to (and often prepared from) phosphorous acid.''Modern Phosphonate Chemistry'' by Philippe Savignac and Bogdan Iorga, CRC Press, Boca Raton, FL, 2003. Phosphonate salts are the result of deprotonation of phosphonic acids, which are diprotic acids: :RPO(OH)2 + NaOH → H2O + RPO(OH)(ONa) (monosodium phosphonate) :RPO(OH)(ONa) + NaOH → H2O + RPO(ONa)2 (disodium phosphonate) Phosphonate esters are the result of condensation of phosphonic acids with alcohols.


Synthesis

Several methods exist for the preparation of phosphonic acids and their salts.


From phosphonic acid

Most processes begin with phosphorous acid (aka phosphonic acid, H3PO3), exploiting its reactive P−H bond. Phosphonic acid can be alkylated under Mannich conditions to give aminomethylated phosphonates, which are useful as complexants. One example is the industrial preparation of nitrilotris(methylenephosphonic acid): :NH3 + 3 H3PO3 + 3 CH2O → N(CH2PO3H2)3 + 3 H2O Phosphonic acid also can be alkylated with
acrylic acid Acrylic acid (IUPAC: propenoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a ...
derivatives to afford carboxyl functionalized phosphonic acids. This reaction is a variant of the Michael addition: :CH2=CHCO2R + 3 H3PO3 → (HO)2P(O)CH2CH2CO2R In the Hirao coupling dialkyl phosphites (which can also be viewed as di-esters of phosphonic acid: (O=PH(OR)2) undergo a palladium-catalyzed coupling reaction with an aryl halide to form a phosphonate.


Michaelis-Arbuzov reaction

Phosphonic esters are prepared using the Michaelis–Arbuzov reaction. For example, methyl iodide catalyses the conversion of trimethylphosphite to the phosphonate ester
dimethyl methylphosphonate Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petroc ...
: :P(OMe)3 → MePO(OMe)2 These esters can be hydrolysed to the acid (Me = methyl): :MePO(OMe)2 + H2O → MePO(OH)2 + 2 MeOH In the
Michaelis–Becker reaction The Michaelis–Becker reaction is the reaction of a hydrogen phosphonate with a base, followed by a nucleophilic substitution of phosphorus on a haloalkane, to give an alkyl phosphonate. Yields of this reaction are often lower than the correspond ...
, a hydrogen phosphonate diester is first deprotonated and the resulting anion is alkylated.


From phosphorus trichloride

Vinylphosphonic acid Vinylphosphonic acid is an organophosphorus compound with the formula C2H3PO3H2.Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," In 'Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2008. . It is a color ...
can be prepared by the reaction of PCl3 and
acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the mos ...
: :PCl3 + CH3CHO → CH3CH(O) This adduct reacts with acetic acid: : CH3CH(O) + 2 CH3CO2H → CH3CH(Cl)PO(OH)2 + 2 CH3COCl This chloride undergoes dehydrochlorination to afford the target: :CH3CH(Cl)PO(OH)2 → CH2=CHPO(OH)2 + HCl In the Kinnear–Perren reaction alkylphosphonyl dichlorides and esters are generated by
alkylation Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...
of
phosphorus trichloride 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 a ...
in the presence of
aluminium trichloride Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contam ...
. Alkyltrichlorophosphonium salts are intermediates: :PCl3 + RCl + AlCl3 → RPCl + AlCl The RPCl product can then be decomposed with water to produce an alkylphosphonic dichloride RP(=O)Cl2.


Reactions


Hydrolysis

Phosphonate esters are generally susceptible to hydrolysis under both acidic and basic conditions. Cleavage of the P-C bond is harder but can be achieved under aggressive conditions. :O=PC(OR)2 + 2 H2O → O=PC(OH)2 + 2 ROH


Horner–Wadsworth–Emmons reaction

In the
Horner–Wadsworth–Emmons reaction The Horner–Wadsworth–Emmons (HWE) reaction is a chemical reaction used in organic chemistry of stabilized phosphonate carbanions with aldehydes (or ketones) to produce predominantly E-alkenes. In 1958, Leopold Horner published a modifi ...
dialkyl-phosphonates are deprotonated to give stabilized carbanions, which react with aldehydes to give E-alkenes with elimination of a dialkyl-
phosphate 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 . The phosphate or orthophosphate ion is derived from phospho ...
. :


Structural sub-classes


Bisphosphonates

Compounds containing 2 geminal phosphonate groups are known as
bisphosphonates Bisphosphonates are a class of drugs that prevent the loss of bone density, used to treat osteoporosis and similar diseases. They are the most commonly prescribed drugs used to treat osteoporosis. They are called bisphosphonates because they h ...
. They were first synthesized in 1897 by Von Baeyer and
Hofmann Hoffman is a surname of German and Jewish origin. The original meaning in medieval times was "steward", i.e. one who manages the property of another. In English and other European languages, including Yiddish and Dutch, the name can also be spelle ...
and now form the basis for an important class of drugs, used to treat osteoporosis and similar diseases. Examples include HEDP (etidronic acid or Didronel), which is prepared from phosphorous acid and
acetic anhydride Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a col ...
: :2 H3PO3 + (CH3CO)2O → CH3C(OH)(PO3H2)2 + CH3CO2H


Thiophosphonates

A thiophosphonate group is a functional group related to phosphonate by substitution of an oxygen atom for a sulphur. They are a reactive component of many
pesticide 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 lampri ...
s and nerve agents. Substituted thiophosphonates can have 2 main
structural isomer In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a chemical compound, compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct chemical bond, b ...
s bonding though either O or S groups to give thione and thiol forms respectively. This is a property they share with related functional groups such as
thiocarboxylic acid In organic chemistry, thiocarboxylic acids are organosulfur compounds related to carboxylic acids by replacement of one of the oxygen atoms with a sulfur atom. Two tautomers are possible: a Thioketone, thione form () and a thiol form (). These ar ...
s and
organothiophosphate Organothiophosphates or organophosphorothioates are a subclass of organophosphorus compounds. Many are used as pesticides, some have medical applications, and some are used as oil additives. They generally have the chemical formula (RO)3PS, RO)2P( ...
s.


Phosphonamidates

Phosphonamidates are related to phosphonates by substitution of an oxygen atom for a nitrogen. They are a rarely encountered functional group. The nerve agent Tabun is an example.


Occurrence in nature

Phosphonates are one of the three sources of phosphate intake in biological cells. The other two are inorganic phosphate and organophosphates. The naturally occurring phosphonate 2-aminoethylphosphonic acid was first identified in 1959 in plants and many animals, where it is localized in membranes. Phosphonates are quite common among different organisms, from
prokaryote A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connec ...
s to
eubacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
and
mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...
s,
mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is e ...
s,
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s and others. They were first reported in natural soils by Newman and Tate (1980). The biological role of the natural phosphonates is still poorly understood. Bis- or polyphosphonates have not been found to occur naturally. A number of natural product phosphonate substances with
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
properties have been identified. Phosphonate natural product antibiotics include
fosfomycin Fosfomycin, sold under the brand name Monurol among others, is an antibiotic primarily used to treat lower UTI. It is not indicated for kidney infections. Occasionally it is used for prostate infections. It is generally taken by mouth. Common ...
which is approved by FDA for the treatment of non-complicated
urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...
as well as several pre-clinically investigated substances such as Fosmidomycin (inhibitor isoprenyl synthase), SF-2312 (inhibitor of the glycolytic enzyme
enolase Phosphopyruvate hydratase, usually known as enolase, is a metalloenzyme () that catalyses the conversion of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP), the ninth and penultimate step of glycolysis. The chemical reaction is: :2-p ...
, and substances of unknown mode of actions such as alahopcin. Although phosphonates are profoundly cell impermeable, natural product phosphonate antibiotics are effective against a number of organisms, because many bacterial species express glycerol-3-phosphate and glucose-6-phosphate importers, which can be hijacked by phosphonate antibiotics. Fosfomycin resistant bacterial strains frequently have mutations that inactivate these transporters; however, such mutations are not maintained in the absence of antibiotic because of the fitness cost they impose.


Uses

In 1998 the consumption of phosphonates was 56,000 tons worldwide – 40,000 tons in the US, 15,000 tons in Europe and less than 800 tons in Japan. The demand of phosphonates grows steadily at 3% annually.


Metal chelants

Since the work of Gerold Schwarzenbach in 1949, phosphonic acids are known as effective
chelating agent Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...
s. The introduction of an
amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...
group into the molecule to obtain −NH2−C−PO(OH)2 increases the metal binding abilities of the phosphonate. Examples for such compounds are NTMP, EDTMP and DTPMP. These phosphonates are the structural analogues to the well-known
aminopolycarboxylate left, 120px, a metal complex with the EDTA anion 120px, Aspartic acid is an aminodicarboxylic acid and precursor to other ligands. An aminopolycarboxylic acid (sometimes abbreviated APCA) is a chemical compound containing one or more nitrogen at ...
such as EDTA. The stability of the metal complexes increases with increasing number of phosphonic acid groups. Phosphonates are highly water-soluble while the phosphonic acids are only sparingly so. Phosphonates are effective chelating agents. That is, they bind tightly to di- and trivalent metal ions, which is useful in
water softening Water softening is the removal of calcium, magnesium, and certain other metal cations in hard water. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. Soft water also extend ...
. In this way, they prevent formation of insoluble precipitates (scale). The binding of these ligands also suppresses the catalytic properties of metal ions. They are stable under harsh conditions. For these reasons, an important industrial use of phosphonates is in cooling waters, desalination systems, and in oil fields to inhibit scale formation. Phosphonates are also regularly used in reverse osmosis systems as antiscalants. Phosphonates in cooling water systems also serve to control corrosion of iron and steel. In pulp and paper manufacturing and in textile industry they serve as "peroxide bleach stabilizers", by chelating metals that could inactivate the peroxide. In detergents they are used as a combination of chelating agent, scale inhibitor, and bleach stabilizer. Phosphonates are also increasingly used in medicine to treat disorders associated with bone formation and calcium metabolism. Furthermore, they serve as carriers for radionuclides in bone cancer treatments (see samarium-153-ethylene diamine tetramethylene phosphonate).


Concrete admixtures

Phosphonates are also used as concrete retarder. They delay the cement setting time, allowing a longer time to place the concrete or to spread the cement hydration heat on a longer period of time to avoid too high temperature and resulting cracks. They also have favourable dispersing properties and so are investigated as a possible new class of superplasticizers. However, presently, phosphonates are not commercially available as superplasticizers. Superplasticizers are concrete admixtures designed to increase the concrete fluidity and workability of concrete or to decrease its water-to-cement (w/c) ratio. By reducing the water content in concrete, it decreases its porosity, improving so the mechanical properties (compressive and tensile strength) and the durability of concrete (lower water, gas and solutes transport properties).


Medicine

In medicine, phosphonates and bisphosphonates are commonly used as inhibitors of enzymes which utilize phosphates and diphosphates as substrates. Most notably, these enzymes include those that produce the intermediates of cholesterol biosynthesis. Phosphonate nucleotide analogues such as tenofovir, cidofovir and adefovir are critical antiviral medications, which in various pro-drug forms are used for the treatment of
HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...
, hepatitis B and others.


Niche uses

In conjunction with organosilicates, phosphonates are also used to treat "sudden oak death", which is caused by the fungus-like eukaryote '' Phytophthora ramorum''.


Toxicology

The toxicity of phosphonates to organisms living in water is low. Reported values for 48-hour LC50 values for fish are between 0.1 and 1.1 mM. Also the
bioconcentration factor Bioconcentration is the accumulation of a chemical in or on an organism when the source of chemical is solely water. Bioconcentration is a term that was created for use in the field of aquatic toxicology. Bioconcentration can also be defined as the ...
for fish is very low.


Biodegradation

In nature bacteria play a major role in the degradation of phosphonates. Due to the presence of natural phosphonates in the environment, bacteria have evolved the ability to metabolize phosphonates as nutrient sources. Some bacteria use phosphonates as a phosphorus source for growth. Aminophosphonates can also be used as sole nitrogen source by some bacteria. The polyphosphonates used in industry differ greatly from natural phosphonates such as 2-aminoethylphosphonic acid, because they are much larger, carry a high negative charge and are complexed with metals. Biodegradation tests with sludge from municipal sewage treatment plants with HEDP and NTMP showed no indication for any degradation. An investigation of HEDP, NTMP, EDTMP and DTPMP in standard biodegradation tests also failed to identify any biodegradation. It was noted, however, that in some tests due to the high sludge to phosphonate ratio, removal of the test substance from solution observed as loss of DOC was observed. This factor was attributed to adsorption rather than biodegradation. However, bacterial strains capable of degrading aminopolyphosphonates and HEDP under P-limited conditions have been isolated from soils, lakes, wastewater, activated sludge and compost. "No biodegradation of phosphonates during water treatment is observed but photodegradation of the Fe(III)-complexes is rapid. Aminopolyphosphonates are also rapidly oxidized in the presence of Mn(II) and oxygen and stable breakdown products are formed that have been detected in wastewater. The lack of information about phosphonates in the environment is linked to analytical problems of their determination at trace concentrations in natural waters. Phosphonates are present mainly as Ca and Mg-complexes in natural waters and therefore do not affect metal speciation or transport." Phosphonates interact strongly with some surfaces, which results in a significant removal in technical and natural systems.


Phosphonate compounds

* Tenofovir alafenamide: A pro-drug of the nucleotide analogue tenofovir, critical for HIV treatment. *AMPA: Aminomethylphosphonic acid, degradation product of glyphosate *
Vinylphosphonic acid Vinylphosphonic acid is an organophosphorus compound with the formula C2H3PO3H2.Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," In 'Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2008. . It is a color ...
: monomer *
Dimethyl methylphosphonate Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petroc ...
(DMMP), one of the simplest phosphonate diesters * Etidronic acid (HEDP): 1-hydroxyethylidene-1,1-diphosphonic acid, used in detergents, water treatment, cosmetics and pharmaceuticals * ATMP: Aminotris(methylenephosphonic acid), chelating agent * EDTMP: Ethylenediaminetetra(methylenephosphonic acid), chelating agent *TDTMP: Tetramethylenediaminetetra(methylenephosphonic acid), chelating agent *HDTMP: Hexamethylenediaminetetra(methylenephosphonic acid), chelating agent *
DTPMP , Section2={{Chembox Properties , Formula=C9H28N3O15P5 , MolarMass = 573.20 , Appearance= solid , Density= , MeltingPt= , BoilingPt= , Solubility= , Section3={{Chembox Hazards , MainHazards= , FlashPt= , AutoignitionPt = DTPMP ...
: Diethylenetriaminepenta(methylenephosphonic acid), chelating agent *PBTC: Phosphonobutanetricarboxylic acid *PMIDA: N-(phosphonomethyl)iminodiacetic acid *CEPA: 2-carboxyethyl phosphonic acid *HPAA: 2-Hydroxyphosphonocarboxylic acid *AMP: Aminotris(methylenephosphonic acid) *BPMG: ''N'',''N''-Bis(phosphonomethyl)glycine * Glyphosate: a common agricultural herbicide * Foscarnet: for treatment of herpes *
Perzinfotel Perzinfotel (EAA-090) is a drug which acts as a potent NMDA antagonist. It has neuroprotective Neuroprotection refers to the relative preservation of neuronal structure and/or function. In the case of an ongoing insult (a neurodegenerative insult ...
: for treatment of stroke *
SF2312 SF may refer to: Locations * San Francisco, California, United States * Sidi Fredj, Algeria * South Florida, an urban region in the United States * Suomi Finland, former vehicular country code for Finland In arts and entertainment Genres ...
: a natural product phosphonate antibiotic inhibitor of
enolase Phosphopyruvate hydratase, usually known as enolase, is a metalloenzyme () that catalyses the conversion of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP), the ninth and penultimate step of glycolysis. The chemical reaction is: :2-p ...
*
Selfotel Selfotel (CGS-19755) is a drug which acts as a competitive NMDA antagonist, directly competing with glutamate for binding to the receptor. Initial studies showed it to have anticonvulsant, anxiolytic, analgesic and neuroprotective effects, and it ...
: an abandoned experimental drug for stroke


See also

* Organophosphorus compounds *
Phosphine oxide Phosphine oxides are phosphorus compounds with the formula OPX3. When X = alkyl or aryl, these are organophosphine oxides. Triphenylphosphine oxide is an example. An inorganic phosphine oxide is phosphoryl chloride (POCl3). Structure and bonding ...
– OPR3 *
Phosphinite In organic chemistry, phosphinites are organophosphorus compounds with the formula . They are used as ligands in homogeneous catalysis and coordination chemistry. Preparation Phosphinites are prepared by alcoholysis of organophosphinous chlori ...
– P(OR)R2 *
Phosphonite In organic chemistry, phosphonites are organophosphorus compounds with the formula P(OR)2R. They are found in some pesticides and are used as ligands. Preparation Although they are derivatives of phosphonous acid (RP(OH)2), they are not prepar ...
– P(OR)2R * Phosphite – P(OR)3 *
Phosphinate Phosphinates or hypophosphites are a class of phosphorus compounds conceptually based on the structure of hypophosphorous acid. IUPAC prefers the term phosphinate in all cases, however in practice hypophosphite is usually used to describe inorganic ...
– OP(OR)R2 *
Phosphate 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 . The phosphate or orthophosphate ion is derived from phospho ...
– OP(OR)3


References


Further reading

* * * {{Organophosphorus Functional groups * * Chelating agents Concrete admixtures