Hypofluorous acid

Hypofluorous acid, chemical formula HOF, is the only known oxoacid of fluorine and the only known oxoacid in which the main atom gains electrons from oxygen to create a negative oxidation state. The oxidation state of the oxygen in hypofluorites is 0. It is also the only hypohalous acid that can be isolated as a solid. HOF is an intermediate in the oxidation of water by fluorine, which produces hydrogen fluoride, oxygen difluoride, hydrogen peroxide, ozone and oxygen. HOF is explosive at room temperature, forming HF and O2:

2 HOF → 2 HF + O2[1]
Hypofluorous acid

Gas-phase structure
Names
IUPAC name
Hypofluorous acid
Other names
Hydrogen hypofluorite
Hydrogen fluorate(-I)
Fluoric(-I) acid
Hydrogen monofluoroxygenate(0)
hydroxyl fluoride
Identifiers
3D model (JSmol)
ChemSpider
Properties
HOF
Molar mass 36.0057 g mol−1
Appearance pale yellow liquid above −117 °C
white solid below −117 °C
Melting point −117 °C (−179 °F; 156 K)
Boiling point
decomposes at 0 °C  
Structure
Cs
Hazards
Main hazards strong oxidizer, corrosive
NFPA 704 (fire diamond)
Related compounds
Other cations
 lithium hypofluorite
Related compounds
 hypochlorous acid
nitroxyl
hydrogen cyanide
formaldehyde
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

It was isolated in the pure form by passing F2 gas over ice at −40 °C, collecting the HOF gas, and condensing it:

F2 + H2O → HOF + HF

The compound has been characterized in the solid phase by X-ray crystallography[1] as a bent molecule with an angle of 101°. The O–F and O–H bond lengths are 144.2 and 96.4 picometres, respectively. The solid framework consists of chains with O–H···O linkages. The structure has also been analyzed in the gas phase, a state in which the H–O–F bond angle is slightly narrower (97.2°).

Hypofluorous acid in acetonitrile (generated in situ by passing gaseous fluorine through "wet" acetonitrile) is commonly known as Rozen's reagent.[2][3][4]

Hypofluorites

Hypofluorites are formally derivatives of OF−, which is the conjugate base of hypofluorous acid. One example is trifluoromethyl hypofluorite (CF3OF).

See also
  • Hypochlorous acid, a related compound that is more technologically important but has not been obtained in pure form.

References
  1. W. Poll; G. Pawelke; D. Mootz; E. H. Appelman (1988). "The Crystal Structure of Hypofluorous Acid : Chain Formation by O-H · · · O Hydrogen Bonds". Angew. Chem. Int. Ed. Engl. 27 (3): 392–3. doi:10.1002/anie.198803921.
  2. Rozen, Shlomo (2001). "Hypofluorous Acid". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rh074. ISBN 0471936235.
  3. Rozen, Shlomo (2014). "HOF·CH3CN: Probably the Best Oxygen Transfer Agent Organic Chemistry Has To Offer". Acc. Chem. Res. 47 (8): 2378–2389. doi:10.1021/ar500107b. PMID 24871453.
  4. Singh, Raman; Kaur, Rajneesh; Gupta, Tarang; Kulbir, Kulbir; Singh, Kuldeep (2019). "Applications of Rozen's Reagent in Oxygen-Transfer and C-H Activation Reactions". Synthesis. 51 (2): 371–383. doi:10.1055/s-0037-1609638.
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