Phosphonate
Encyclopedia
Aryl
In the context of organic molecules, aryl refers to any functional group or substituent derived from an aromatic ring, be it phenyl, naphthyl, thienyl, indolyl, etc....
). Bisphosphonates were first synthesized in 1897 by Von Baeyer and Hofmann. An example of such a bisphosphonate is HEDP
Etidronic acid
Etidronic acid or 1-hydroxyethane 1,1-diphosphonic acid is a bisphosphonate used in detergents, water treatment, cosmetics and pharmaceutical treatment....
(Etidronic acid or Didronel). Since the work of Schwarzenbach
Gerold Schwarzenbach
Gerold Karl Schwarzenbach was a Swiss chemist.Schwarzenbach was born and grew up in Horgen, Switzerland. He studied chemistry at the ETH Zurich and graduated in 1928 with his dissertation Studien über die Salzbildung von Beizenfarbstoffen...
in 1949, phosphonic acids are known as effective chelating agents. The introduction of an amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
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 common phosphonates are the structure analogues to the well-known aminopolycarboxylates NTA
Nitrilotriacetic acid
Nitrilotriacetic acid , C6H9NO6, is a polyamino carboxylic acid and is used as a chelating agent which forms coordination compounds with metal ions such as Ca2+, Cu2+ or Fe3+.The uses of NTA are similar to that of EDTA...
, EDTA
EDTA
Ethylenediaminetetraacetic acid, widely abbreviated as EDTA , is a polyamino carboxylic acid and a colourless, water-soluble solid. Its conjugate base is named ethylenediaminetetraacetate. It is widely used to dissolve limescale. Its usefulness arises because of its role as a hexadentate ligand...
, and DTPA. 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 soluble. Phosphonates are not volatile and are poorly soluble in organic solvents.
Phosphonate compounds
- AEPn: 2-Aminoethylphosphonic acid
- DMMP: Dimethyl methylphosphonate
- HEDPEtidronic acidEtidronic acid or 1-hydroxyethane 1,1-diphosphonic acid is a bisphosphonate used in detergents, water treatment, cosmetics and pharmaceutical treatment....
: 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid - ATMPATMPATMP or aminotris is a phosphonic acid. It has chelating properties.-Properties:ATMP has better antiscale performance than that of polyphosphate through its excellent chelating ability, low threshold inhibition and lattice distortion process. It can prevent scale formation in water systems...
: Amino tris(methylene phosphonic acid) - EDTMPEDTMPEDTMP or ethylenediamine tetra is a phosphonic acid. It has chelating and anti corrosion properties. EDTMP is the phosphonate analog of EDTA.-Properties:...
: Ethylenediamine tetra(methylene phosphonic acid) - TDTMP: Tetramethylenediamine tetra(methylene phosphonic acid)
- HDTMP: Hexamethylenediamine tetra(methylene phosphonic acid)
- DTPMPDTPMPDTPMP or diethylenetriamine penta is a phosphonic acid. It has chelating and anti corrosion properties.-Properties:...
: Diethylenetriamine penta(methylene phosphonic acid) - PBTC: Phosphonobutane-tricarboxylic acid
- PMIDA: N-(phosphonomethyl)iminodiacetic acid
- CEPA: 2-carboxyethyl phosphonic acid
- HPAA: 2-Hydroxyphosphonocarboxylic acid
- AMP: Amino-tris-(methylene-phosphonic acid)
Occurrence in nature
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 prokaryotes to eubacteria and fungi, mollusks, insects and others. The biological role of the natural phosphonates is still poorly understood. Bis- or polyphosphonates have not been found to occur naturally.Properties and uses
Phosphonates are effective chelating agents that bind tightly to di- and trivalent metal ions, preventing them from forming insoluble precipitates (scale) and suppressing their catalytic properties. They are stable under harsh conditions. An important industrial use of phosphonates is in cooling waters, desalination systems, and in oil fields to inhibit scale formation. 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 phosphonateSamarium-153-ethylene diamine tetramethylene phosphonate
Samarium lexidronam is a complex of a radioisotope of the lanthanide element samarium with the chelator EDTMP. It is used to treat pain when cancer has spread to the bone.It is injected into a vein and distributes throughout the body...
).
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.
In conjunction with organosilicates, phosphonates are also used to treat "sudden oak death
Sudden oak death
Sudden Oak Death is the common name of a disease caused by the oomycete plant pathogen Phytophthora ramorum. The disease kills oak and other species of tree and has had devastating effects on the oak populations in California and Oregon as well as also being present in Europe...
", which is caused by the fungus-like eukaryote Phytophthora ramorum.
Toxicology
The toxicity of phosphonates to aquatic organisms is low. Reported values for 48 h LC50 values for fish are between 0.1 and 1.1 mM. Also the bioconcentration factorBioconcentration factor
Bioconcentration factor is the concentration of a particular chemical in a biological tissue per concentration of that chemical in water surrounding that tissue...
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 are one of the three sources of phosphate intake in biological cells (The other two being inorganic phosphate and organophosphate)
Environmental behavior
Phosphonates have a very strong interaction with surfaces, which results in a significant removal in technical and natural systems. Due to this strong adsorption, little or no remobilization of metals is expected.Synthesis and reactions
Phosphonates can be synthesized using the Michaelis–Arbuzov reaction. In one study a α-aminophosphonate is prepared by condensationCondensation reaction
A condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride,...
of benzaldehyde
Benzaldehyde
Benzaldehyde is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. This colorless liquid has a characteristic pleasant almond-like odor...
, aniline
Aniline
Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...
, and trimethyl phosphite
Trimethyl phosphite
Trimethylphosphite is an organophosphorus compound with the formula P3, often abbreviated P3. This colorless liquid is used as a ligand in organometallic chemistry and as a reagent in organic synthesis...
catalyzed by Copper triflate in a one-pot synthesis
One-pot synthesis
In chemistry a one-pot synthesis is a strategy to improve the efficiency of a chemical reaction whereby a reactant is subjected to successive chemical reactions in just one reactor...
.
The phosphonates (and other phosphorus esters) can also be synthesized via transesterification reaction catalyzed by organic catalysts. N-heterocyclic carbenes have been reported to catalyze the reaction efficiently.
In organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
, phosphonates are used in the Horner-Wadsworth-Emmons reaction
Horner-Wadsworth-Emmons reaction
The Horner-Wadsworth-Emmons reaction is the chemical reaction of stabilized phosphonate carbanions with aldehydes to produce predominantly E-alkenes....
.
See also
- OrganophosphorusOrganophosphorusOrganophosphorus compounds are degradable organic compounds containing carbon–phosphorus bonds , used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment...
compounds - PhosphinePhosphinePhosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
- PR3 - Phosphine oxidePhosphine oxidePhosphine oxides are either inorganic phosphorus compounds such as phosphoryl trichloride or organophosphorus compounds with the formula OPR3, where R = alkyl or aryl...
- OPR3 - PhosphinitePhosphinitePhosphinites are organophosphorus compounds with the formula PR2. They are esters of phosphinous acid.-See also:*Phosphine - PR3*Phosphine oxide - OPR3*Phosphonite - P2R*Phosphite - P3*Phosphinate - OPR2*Phosphonate - OP2R...
- P(OR)R2 - PhosphonitePhosphonitePhosphonites are organophosphorus compounds with the formula P2R. They are derivivatives of phosphonous acid.- See also :*Phosphine - PR3*Phosphine oxide - OPR3*Phosphinite - PR2*Phosphinate - OPR2...
- P(OR)2R - PhosphitePhosphiteA phosphite is a salt of phosphorous acid. The phosphite ion is a polyatomic ion with a phosphorus central atom where phosphorus has an oxidation state of +3...
- P(OR)3 - PhosphinatePhosphinatePhosphinates are organophosphorus compounds with the formula OPR2.-See also:*Phosphine - PR3*Phosphine oxide - OPR3*Phosphinite - PR2*Phosphonite - P2R*Phosphite - P3*Phosphonate - OP2R*Phosphate - OP3...
- OP(OR)R2 - PhosphatePhosphateA phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
- OP(OR)3
methyl phosphonic acid is used as active ingredient in scale inhibitor.