PBTC; PBTCA; FOSFONOBUTANE TRICARBOXYLIC ASİT; 2-Fosfonobutan-1,2,4-Trikarboksilik Asit; 2-Fosfonobutan-1,2,4-trikarboksilik asit PBTC; Phosphonates and phosphonic acids are organophosphorus compounds containing C−PO(OH)2 or C−PO(OR)2 groups (where R = alkyl, aryl). Phosphonic acids, typically handled as salts, are generally nonvolatile solids that are poorly soluble in organic solvents, but soluble in water and common alcohols. Many commercially important compounds are phosphonates, including glyphosate (the active molecule of the herbicide "Roundup"), and ethephon, a widely used plant growth regulator. Bisphosphonates are popular drugs for treatment of osteoporosis.
Clodronic acid is a bisphosphonate used as a drug to treat osteoporosis.
In biology and medicinal chemistry, phosphonate groups are used as stable bioisoteres for phosphate, such as in the antiviral nucleotide analogue, Tenofovir, one of the cornerstones of anti-HIV therapy.
1 Basic properties
2.1 From phosphonic acid
2.2 Michaelis-Arbuzov reaction
2.3 From phosphorus trichloride
3 Occurrence in nature
4.1 Metal chelants
5.1 Niche uses
8 Phosphonate compounds
9 See also
11 Further reading
Phosphonates feature tetrahedral phosphorus centers. They are structurally closely related to (and often prepared from) phosphorous acid.
Phosphonic acids and derivatives are chemically and structurally related to phosphorous acid.
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.
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 derivatives to afford carboxyl functionalized phosphonic acids. This reaction is a variant of the Michael addition:
CH2=CHCO2R + 3 H3PO3 → (HO)2P(O)CH2CH2CO2R