Phosphinous acid

Phosphinous acid is the inorganic compound with the formula H₂POH. It exists, fleetingly, as a mixture with its less stable tautomer H₃PO (phosphine oxide). This mixture has been generated by low temperature oxidation of phosphine with ozone.^[1] H₂POH is mainly of pedagogical interest. Organophosphinous acids are more prevalent than the parent H₂POH.

Phosphinous acid

Names
Other names hydroxyphosphine
Identifiers
CAS Number	13840-40-9
3D model (JSmol)	Interactive image
ChemSpider	126521
PubChem CID	143409
CompTox Dashboard (EPA)	DTXSID80276387
InChI InChI=1S/H3OP/c1-2/h1H,2H2 Key: RYIOLWQRQXDECZ-UHFFFAOYSA-N
SMILES OP
Properties
Chemical formula	H3OP
Molar mass	49.997 g·mol−1
Related compounds
Related compounds	Hydroxylamine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Organophosphinous acids

Phosphinous acids exist mainly as minor tautomers of secondary phosphine oxides. For example diphenylphosphinous acid, which is not detectable directly, is invoked as the tautomer of diphenylphosphine oxide.

Highly electron-withdrawing substituents stabilize the phosphinous acid tautomer as illustrated by (CF₃)₂POH.^[2]