Difluorophosphoric acid

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Difluorophosphoric acid
HPO2F2.svg
Names
IUPAC name
Difluorophosphinic acid [1]
Other names
  • Difluorophosphoric acid
  • Fluophosphoric acid [1]
  • Phosphorodifluoridic acid [1]
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.034.005 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 237-421-6
PubChem CID
UNII
UN number 1768
  • InChI=1S/F2HO2P/c1-5(2,3)4/h(H,3,4)
    Key: DGTVXEHQMSJRPE-UHFFFAOYSA-N [1]
  • OP(=O)(F)F
Properties
HPO2F2
Molar mass 101.977 g·mol−1
AppearanceColorless liquid [1]
Density 1.583 g/cm3 [1] [2]
Melting point −96.5 °C (−141.7 °F; 176.7 K) [2]
Boiling point 115.9 °C (240.6 °F; 389.0 K) [2]
Structure
Tetrahedral at phosphorus atom
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Corrosive to living tissue
GHS labelling:
GHS-pictogram-acid.svg
Danger
H314
P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Difluorophosphoric acid is an inorganic compound with the formula HPO2F2. It is a mobile colorless strongly fuming liquid. [1] The acid has limited applications, in part because it is thermally and hydrolytically unstable. [3] Difluorophosphoric acid is corrosive to glass, fabric, metals and living tissue. [1]

A method to make pure difluorphosphoric acid involves heating phosphoryl fluoride with fluorophosphoric acid and separating the product by distillation: [4]

POF3 + H2PO3F → 2 HPO2F2

It is prepared by hydrolysis of phosphoryl fluoride:

POF3 + H2O → HPO2F2 + HF

Further hydrolysis gives fluorophosphoric acid:

HPO2F2 + H2O → H2PO3F + HF

Complete hydrolysis gives phosphoric acid:

H2PO3F + H2O → H3PO4 + HF

The salts of difluorophosphoric acid are known as difluorophosphates.

References

  1. 1 2 3 4 5 6 7 8 "Difluorophosphoric acid".
  2. 1 2 3 Reed, William (September 1965). Studies of Difluorophosphoric Acid and its Alkali Metal Salts (Thesis). Retrieved 23 April 2023.
  3. ↑ Charles B. Lindahl; Tariq Mahmood (2000). "Fluorine Compounds, Inorganic, Phosphorus". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.1608151912091404.a01. ISBN   0-471-23896-1.
  4. ↑ Lange, Willy; Livingston, Ralph (March 1950). "Studies of Fluorophosphoric Acids and their Derivatives. XIV. Preparation of Anhydrous Difluorophosphoric Acid". Journal of the American Chemical Society. 72 (3): 1280–1281. Bibcode:1950JAChS..72.1280L. doi:10.1021/ja01159a057.
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