Nitronium tetrafluoroborate

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Nitronium tetrafluoroborate
IUPAC name
Nitronium tetrafluoroborate
Preferred IUPAC name
Nitronium tetrafluoroborate
Other names
Nitronium tetrafluoroborate
Nitryl tetrafluoroborate
Molar mass 132.81 g/mol
Appearance Colorless crystalline solid
Odor Odorless
Density 1.29 g/cm3 (20 °C)
Melting point 180 °C (356 °F; 453 K) (decomposes)
Boiling point Decomposes
Solubility Reacts with acetic acid, dimethylacetamide, dimethylformamide, THF
Soluble in acetonitrile, sulfolane
Slightly soluble in nitromethane, trifluoroacetic acid
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
180 mg/kg (mouse, IV)
Related compounds
Related compounds
Ammonium tetrafluoroborate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Nitronium tetrafluoroborate is an inorganic compound with the chemical formula NO2BF4. It is a salt of nitronium cation and tetrafluoroborate anion.



Nitronium tetrafluoroborate is used as a nitration agent, replacing the nitrating mixture in many reactions, although due to its poor solubility in many solvents, it's sometimes replaced with the more soluble nitronium hexafluorophosphate.

Nitronium tetrafluoroborate reacts with water.

NO2BF4 + H2O → HNO3 + HBF4

It also reacts rapidly with acetic anhydride, but less so with acetic acid, dimethylformamide and even slower with acetonitrile, although the reaction is faster at high temperatures. Reaction with acetic acid yields acetyl nitrate. It does not react with sulfolane, which is why it's commonly used as reaction solvent.[1]

NO2BF4 decomposes if heated to 180 °C to NO2F and BF3.[2]

Nitronium tetrafluoroborate oxidizes organic sulfides to sulfoxides. Excess NO2BF4 further oxidizes the sulfoxide to sulfone. Phosphines are similarly oxidized to phosphine oxides.


Nitronium tetrafluoroborate is a hygroscopic colorless solid.


Nitronium tetrafluoroborate is sold by chemical suppliers.


Nitronium tetrafluoroborate can be prepared by adding a mixture of anhydrous hydrogen fluoride and boron trifluoride to a nitromethane solution of 100% nitric acid or dinitrogen pentoxide. Nitrosonium tetrafluoroborate is also produced as side-product, if the nitric acid used contains traces of nitrogen oxides (such as RFNA).[3]


  • Aromatic nitration
  • Make acetyl nitrate



Nitronium tetrafluoroborate reacts with water and it's highly corrosive as well as toxic.


In closed airtight bottles.


Should be added slowly to water to safely hydrolyze it, then neutralized with a base.


  1. Kenneth Schofield, Aromatic Nitration, 1980, p. 88

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