difluorophosphoric acid

{{Chembox

|ImageFile = HPO2F2.svg

|ImageSize = 140

|IUPACName = Difluorophosphinic acid

|OtherNames = {{ubl|Difluorophosphoric acid|Fluophosphoric acid|Phosphorodifluoridic acid}}

|Section1 = {{Chembox Identifiers

|CASNo = 13779-41-4

| ChemSpiderID = 55585

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = 3QNA5YG39L

|PubChem = 61681

|EC_number = 237-421-6

|UNNumber = 1768

|InChI = 1S/F2HO2P/c1-5(2,3)4/h(H,3,4)

|InChIKey = DGTVXEHQMSJRPE-UHFFFAOYSA-N

|SMILES = OP(=O)(F)F

}}

|Section2 = {{Chembox Properties

|Formula = {{chem2|HPO2F2}}

|F=2|H=1|O=2|P=1

|Appearance = Colorless liquid

|Density = 1.583 g/cm³

|MeltingPtC = −96.5

|BoilingPtC = 115.9

|MeltingPt_ref = {{cite thesis|last1=Reed|first1=William|title=Studies of Difluorophosphoric Acid and its Alkali Metal Salts|date=September 1965|url=https://open.library.ubc.ca/media/download/pdf/831/1.0062126/2|access-date=23 April 2023}}

|BoilingPt_ref =

}}

|Section3 = {{Chembox Structure

|MolShape = Tetrahedral at phosphorus atom

}}

|Section7 = {{Chembox Hazards

|MainHazards = Corrosive to living tissue

|GHSPictograms = {{GHS05}}

|GHSSignalWord = Danger

|HPhrases = {{H-phrases|314}}

|PPhrases = {{P-phrases|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|405|501}}

}}

}}

Difluorophosphoric acid is an inorganic compound with the formula {{chem2|HPO2F2}}. It is a mobile colorless strongly fuming liquid.{{cite web | url=https://pubchem.ncbi.nlm.nih.gov/compound/Difluorophosphoric-acid | title=Difluorophosphoric acid }} The acid has limited applications, in part because it is thermally and hydrolytically unstable.{{cite encyclopedia|title=Fluorine Compounds, Inorganic, Phosphorus|author=Charles B. Lindahl |author2=Tariq Mahmood |encyclopedia=Kirk-Othmer Encyclopedia of Chemical Technology|year=2000|doi=10.1002/0471238961.1608151912091404.a01|isbn=0-471-23896-1}} Difluorophosphoric acid is corrosive to glass, fabric, metals and living tissue.

A method to make pure difluorphosphoric acid involves heating phosphoryl fluoride with fluorophosphoric acid and separating the product by distillation:{{cite journal|last1=Lange|first1=Willy|last2=Livingston|first2=Ralph|title=Studies of Fluorophosphoric Acids and their Derivatives. XIV. Preparation of Anhydrous Difluorophosphoric Acid|journal=Journal of the American Chemical Society|date=March 1950|volume=72|issue=3|pages=1280–1281|doi=10.1021/ja01159a057|bibcode=1950JAChS..72.1280L }}

:{{chem2|POF3 + H2PO3F → 2 HPO2F2}}

It is prepared by hydrolysis of phosphoryl fluoride:

:{{chem2|POF3 + H2O → HPO2F2 + HF}}

Further hydrolysis gives fluorophosphoric acid:

:{{chem2|HPO2F2 + H2O → H2PO3F + HF}}

Complete hydrolysis gives phosphoric acid:

:{{chem2|H2PO3F + H2O → H3PO4 + HF}}

The salts of difluorophosphoric acid are known as difluorophosphates.