Fluoroboric acid

Fluoroboric acid
Canonical, skeletal formula of oxonium tetrafluoroborate
Hydronium tetrafluoroborate
Names
Preferred IUPAC name
Tetrafluoroboric acid[1]
Other names
  • Fluoboric acid
  • Fluoroboric acid
  • Hydrogen tetrafluoroborate
  • Oxonium tetrafluoroboranuide
  • Oxonium tetrafluoridoborate(1-)
  • Oxonium tetrafluoroborate
Identifiers
  • 14219-41-1 ([H3O]+[BF4]−) ☒N
  • 16872-11-0 (solvent free) checkY
  • 80628-99-5 ([H5O2]+[BF4]−) ☒N
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.037.165 Edit this at Wikidata
EC Number
  • 240-898-3
21702
MeSH Fluoroboric+acid
RTECS number
  • ED2685000
UNII
UN number 1775
  • InChI=1S/BF4H/c2-1(3,4)5/h2H ☒N
    Key: YKRRMQXMWYXWJW-UHFFFAOYSA-N ☒N
  • F[B-](F)(F)[FH+]
  • [H+].F[B-](F)(F)F
Properties
H[BF4]
Molar mass 87.81 g·mol−1
Appearance Colourless liquid
Melting point −90 °C (−130 °F; 183 K)
Boiling point 130 °C (266 °F; 403 K)
Acidity (pKa) ~1.8 (MeCN solution)[2]
Hazards
GHS labelling:
GHS05: Corrosive
Danger
H314
P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Safety data sheet (SDS) External MSDS
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Fluoroboric acid or tetrafluoroboric acid (archaically, fluoboric acid) is an inorganic compound with the simplified chemical formula H+[BF4]−. Solvent-free tetrafluoroboric acid (H[BF4]) has not been reported. The term "fluoroboric acid" usually refers to a range of compounds including hydronium tetrafluoroborate ([H3O]+[BF4]−), which are available as solutions. The ethyl ether solvate is also commercially available, where the fluoroboric acid can be represented by the formula [H((CH3CH2)2O)n]+[BF4]−, where n is 2.

It is mainly produced as a precursor to other fluoroborate salts.[3] It is a strong acid. Fluoroboric acid is corrosive and attacks the skin. It is available commercially as a solution in water and other solvents such as diethyl ether. It is a strong acid with a weakly coordinating, non-oxidizing conjugate base.[2] It is structurally similar to perchloric acid, but lacks the hazards associated with oxidants.

  1. ^ IUPAC. "Nomenclature of Inorganic Chemistry". Retrieved 2021-04-08.
  2. ^ a b Kütt, A., et al., "Equilibrium Acidities of Superacids", J. Org. Chem. 2010, volume 76, pp. 391-395. doi:10.1021/jo101409p
  3. ^ Gregory K. Friestad, Bruce P. Branchaud "Tetrafluoroboric Acid" E-Eros Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt035