Difluorophosphoric acid

Difluorophosphoric acid
Names
	IUPAC name Difluorophosphinic acid
	Other names Difluorophosphoric acid; Fluophosphoric acid; Phosphorodifluoridic acid;
Identifiers
CAS Number	13779-41-4;
3D model (JSmol)	Interactive image;
ChemSpider	55585;
ECHA InfoCard	100.034.005
EC Number	237-421-6;
PubChem CID	61681;
UNII	3QNA5YG39L ;
UN number	1768
CompTox Dashboard (EPA)	DTXSID6065632 ;
	InChI InChI=1S/F2HO2P/c1-5(2,3)4/h(H,3,4) Key: DGTVXEHQMSJRPE-UHFFFAOYSA-N;
	SMILES OP(=O)(F)F;
Properties
Chemical formula	HPO2F2
Molar mass	101.977 g·mol−1
Appearance	Colorless liquid
Density	1.583 g/cm3
Melting point	−96.5 °C (−141.7 °F; 176.7 K)
Boiling point	115.9 °C (240.6 °F; 389.0 K)
Structure
Molecular shape	Tetrahedral at phosphorus atom
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Corrosive to living tissue
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	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). Infobox references

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

^ ^a ^b ^c ^d ^e ^f ^g ^h "Difluorophosphoric acid".
^ ^a ^b ^c Reed, William (September 1965). Studies of Difluorophosphoric Acid and its Alkali Metal Salts (Thesis). Retrieved 23 April 2023.
^ 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.
^ 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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[pubchem-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h "Difluorophosphoric acid".

[Reed65-2] 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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