Phosphonate

Phosphonates are salts of the phosphonic acid and organic compounds. As salts exist primary ( ) and secondary ( ) phosphonates. ( M: monovalent metal )

The organic compounds of this group of substances ( phosphites ) have the formula R -PO (OH) 2 (R = alkyl radical or aryl radical ) and differ from the esters of phosphoric acid by the direct bond of phosphorus to carbon ( C-P bond ). In contrast, phosphates are (analogous to sulfates and sulfones ) COP bonds before, which can be hydrolyzed much easier compared to CP bonds. In compounds of this type, the properties of a salt (or acid ) are associated with the properties of the organic compound. So there are many compounds of this type that are soluble in water.

Natural Occurrence

1959 was identified with 2- amino ethyl phosphonic acid, the first natural. It occurs in plants and many animals, especially in membranes. Phosphonates are widely used in many different organisms, such as prokaryotes, eubacteria, fungi, insects and molluscs. The biological role of phosphonates is not yet finally resolved. There are no natural bis-or other polyphosphates have been discovered.

Technical Applications

An important industrial use of phosphonates is in cooling water systems, desalination plants and in oil extraction, where they prevent the precipitation of salts. In the paper and textile industries, they are used as a stabilizer for peroxide bleaching and complex there metals that would otherwise inactivate the peroxide.

In detergent compositions they are used as a combination of chelating agents to prevent precipitation and as a bleaching agent stabilizer. You can have properties similar to EDTA and used as a substitute of triphosphate. You are complexing agents and are mainly used as a water softener. As a builder they can support the ion exchanger or the water softener zeolite A as a carrier. You can participate as corrosion inhibitors or serve as a stabilizer for peroxides (eg, bleach ).

1998, approximately 56,000 tons of phosphonates have been used throughout the world - 40,000 tons in the U.S., 15,000 tons in Europe and less than 800 tons in Japan.

Examples

Herbicides

Main article: glyphosate

One of the best known and most economically important phosphonates is glyphosate ( RoundUp ®), a herbicide from Monsanto containing a phosphonate, a carboxylate and an amino group.

Toxicology

The toxicity of the phosphonates mentioned in the examples is small, the LC50 values ​​for fish are between 0.1 and 1 mM. Also, they are practically not bioaccumulate. These phosphonates in the gastrointestinal tract is very poorly absorbed and most of the absorbed amount is excreted through the kidneys. The human toxicity of these phosphonates is also very low. Phosphonates phosphates are similar to, but have a C-P bond instead of a COP bond. This similarity often leads to that phosphonic acid are inhibitors of many enzymes.

Biodegradation

Bacteria play an important role in the degradation of phosphonates in nature. Bacteria, which can cleave the CP bond can survive with phosphonates as the sole P source. Amino phosphonates can be used by many organisms as a source of nitrogen. The data used in the industry Polyphosphonates differ from the natural phosphonates, as they are much larger, and a strong negative charge and are complexed with metals. Degradation tests with sewage sludge have shown that HEDP and NTMP are not degraded. Also available in standard tests, no degradation of HEDP, NTMP, EDTMP and DTPMP showed. For various environmental compartments ( soil, water, sewage sludge, compost) bacteria could be isolated which are able to reduce under P deficiency HEDP. Generally, bacteria only phosphonates from having a functional group.

Environmental behavior

The phosphonates mentioned in the examples have some properties which distinguish them from other complexing agents and determine what their environmental behavior. Phosphonates react very strongly with surfaces, leading to a strong elimination in technical and natural systems by adsorption, although they are not biodegradable. Therefore phosphonates unlikely to lead to a metal mobilization in the environment. The photochemical reduction of Fe ( III) phosphonates is fast. Aminopolyphosphonates are oxidized rapidly in the presence of manganese (II) and oxygen; the stable products of this reaction were identified in sewage treatment plants. The lack of data on the environmental fate and concentrations of phosphonates in the environment comes from analytical problems with the trace analysis. In natural waters, phosphonates occur mainly as Ca and Mg complexes.

In Medicine

Phosphonates are used in medicine, especially for the treatment of bone diseases and calcium metabolism disorders. Under bisphosphonates used in medicine compounds of the phosphonic acid having the general structural formula ( ( O3P ) 2-C - R1R2 ) 4 - understood. They are analogues to diphosphates ( pyrophosphates ) ( O3P -O- PO3 ) 4 - and engage the calcium homeostasis. They are therefore used, inter alia, for the treatment of osteoporosis and bone metastases.

Synthesis

Mono- and Dialkylphosphonate are visualized via the Michaelis- Arbuzov or Michaelis- Arbuzov Phosphonatsynthese reaction. Halogenated phosphonates can be represented by the Michaelis -Becker reaction. Silyl phosphonates may be formed by a Kinnear -Perren reaction.