View source for Chemistry:Oxygen difluoride

{{chembox
| Watchedfields = changed
| verifiedrevid = 445419652
| Name = Oxygen difluoride
|IUPACName=Oxygen difluoride
| ImageFile = Oxygen-difluoride-2D.png
| ImageSize = 160px
| ImageName = Structure and dimensions of the oxygen difluoride molecule
| ImageFile1 = Oxygen-difluoride-3D-vdW.png
| ImageSize1 = 160px
| ImageName1 = Space-filling model of the oxygen difluoride molecule
| OtherNames = {{Unbulleted list|Oxygen fluoride|Hypofluorous anhydride}}
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22953
| InChI = 1/F2O/c1-3-2
| InChIKey = UJMWVICAENGCRF-UHFFFAOYAI
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 30494
| SMILES = FOF
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/F2O/c1-3-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = UJMWVICAENGCRF-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 7783-41-7
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 7BCS2CW398
| PubChem = 24547
| RTECS = RS2100000
| EINECS = 231-996-7
}}
|Section2={{Chembox Properties
| Formula = {{chem2|OF2}}
| Appearance = colorless gas, pale yellow liquid when condensed
| Odor = peculiar, foul
| MolarMass = 53.9962&nbsp;g/mol
| Density = {{Unbulleted list|1.90{{nbsp}}g/cm<sup>3</sup> (−224{{nbsp}}°C, liquid)|1.719{{nbsp}}g/cm<sup>3</sup> (−183{{nbsp}}°C, liquid)|1.521{{nbsp}}g/cm<sup>3</sup> (liquid at −145{{nbsp}}°C)|1.88{{nbsp}}g/L (gas at room temperature)}}
| Solubility = hydrolyzes<ref>{{cite web|url=http://www.chemyq.com/En/xz/xz1/2818mqnrv.htm|title=difluorine monoxide; oxygen difluoride, physical properties, suppliers, CAS, MSDS, structure, Molecular Formula, Molecular Weight, Solubility, boiling point, melting point|website=www.chemyq.com}}</ref> slowly
| Solvent = slightly soluble in [[Chemistry:Alcohol|alcohol]]
| MeltingPtC = −223.8
| BoilingPtC = −144.75
| VaporPressure = 48.9{{nbsp}}atm (at {{convert|&minus;58.0|C|F K|1|disp=or}}{{efn|This is its [[Physics:Critical temperature|critical temperature]], which is below ordinary [[Physics:Room temperature|room temperature]].}})
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = −24.5{{nbsp}}kJ mol<sup>−1</sup>
| DeltaGf = 42.5{{nbsp}}kJ/mol
| Entropy = 246.98{{nbsp}}J/mol K
| HeatCapacity = 43.3{{nbsp}}J/mol K
}}
|Section5={{Chembox Hazards
| GHSPictograms = {{GHS03}}{{GHS04}}{{GHS05}}{{GHS06}}
| GHSSignalWord = danger
| PPhrases      = {{PPhrases|}}<!-- No P-phrases were specified. -->
| GHS_ref       = <ref>GHS: [https://gestis.dguv.de/data?name=570242 GESTIS 570242]</ref>
| NFPA-H = 4
| NFPA-F = 0
| NFPA-R = 3
| NFPA-S = OX
| PEL = TWA 0.05{{nbsp}}ppm (0.1{{nbsp}}mg/m<sup>3</sup>)<ref name=PGCH>{{PGCH|0475}}</ref>
| IDLH = 0.5{{nbsp}}ppm<ref name=PGCH/>
| LC50 = {{Unbulleted list|2.6{{nbsp}}ppm (rat, 1 hour)|1.5{{nbsp}}ppm (mouse, 1 hour)|26{{nbsp}}ppm (dog, 1 hour)|16{{nbsp}}ppm (monkey, 1 hour)}}<ref>{{IDLH|7783417|Oxygen difluoride}}</ref>
| REL = C 0.05{{nbsp}}ppm (0.1{{nbsp}}mg/m<sup>3</sup>)<ref name=PGCH/> 
}}
|Section8={{Chembox Related
| OtherCompounds = {{Unbulleted list|[[Chemistry:Hypofluorous acid|{{chem2|HFO}}]]|[[Chemistry:Dioxygen difluoride|{{chem2|O2F2}}]]|{{chem2|NHF2}}|[[Chemistry:Nitrogen trifluoride|{{chem2|NF3}}]]|[[Chemistry:Sulfur dichloride|{{chem2|SCl2}}]]|[[Chemistry:Properties of water|{{chem2|H2O}}]]|[[Chemistry:Dichlorine monoxide|{{chem2|Cl2O}}]]|[[Chemistry:Dibromine monoxide|{{Chem2|Br2O}}]]|{{chem2|I2O}}}}}}
}}
'''Oxygen difluoride''' is a [[Chemistry:Chemical compound|chemical compound]] with the [[Chemistry:Chemical formula|formula]] {{chem2|OF2}}. As predicted by [[Physics:VSEPR theory|VSEPR theory]], the molecule adopts a bent [[Physics:Molecular geometry|molecular geometry]]. It is a strong oxidizer and has attracted attention in rocketry for this reason.<ref>{{Cite web |title=Oxygen Difluoride - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/chemistry/oxygen-difluoride |access-date=2023-11-03 |website=www.sciencedirect.com}}</ref> With a [[Physics:Boiling point|boiling point]] of &minus;144.75&nbsp;°C, OF<sub>2</sub> is the most volatile (isolable) triatomic compound.<ref>{{Greenwood&Earnshaw2nd|page=819}}</ref> The compound is one of many known [[Chemistry:Oxygen fluoride|oxygen fluoride]]s.

==Preparation==
Oxygen difluoride was first reported in 1929; it was obtained by the electrolysis of molten [[Chemistry:Potassium fluoride|potassium fluoride]] and [[Chemistry:Hydrofluoric acid|hydrofluoric acid]] containing small quantities of [[Chemistry:Water (molecule)|water]].<ref>{{cite journal |last1=Lebeau |first1=P. |last2=Damiens |first2=A. |year=1929 |title=Sur un nouveau mode de préparation du fluorure d'oxygène |trans-title=A new method of preparation of oxygen fluoride |journal=Comptes rendus hebdomadaires des séances de l'Académie des Sciences |volume=188 |pages=1253–1255 |language=fr |access-date=February 21, 2013 |url=http://visualiseur.bnf.fr/CadresFenetre?O=NUMM-3141&I=1253&M=chemindefer}}</ref><ref>{{cite journal |last1=Lebeau |first1=P. |author-link=Paul Lebeau |last2=Damiens |first2=A. |year=1927 |title=Sur l'existence d'un composé oxygéné du fluor |trans-title=The existence of an oxygen compound of fluorine |journal=Comptes rendus hebdomadaires des séances de l'Académie des Sciences |volume=185 |pages=652–654 |language=fr |access-date=February 21, 2013 |url=http://visualiseur.bnf.fr/CadresFenetre?O=NUMM-3138&I=652&M=tdm}}</ref> The modern preparation entails the reaction of [[Chemistry:Fluorine|fluorine]] with a dilute aqueous solution of [[Chemistry:Sodium hydroxide|sodium hydroxide]], with [[Chemistry:Sodium fluoride|sodium fluoride]] as a side-product:
:{{chem2|2 F2 + 2 NaOH -> OF2 + 2 NaF + H2O}}
==Structure and bonding==
It is a covalently bonded molecule with a [[Physics:Bent molecular geometry|bent molecular geometry]] and a F-O-F bond angle of 103 degrees. Its powerful oxidizing properties are suggested by the oxidation number of +2 for the [[Chemistry:Oxygen|oxygen]] atom instead of its normal −2.

==Reactions==
Above 200&nbsp;°C, {{chem2|OF2}} decomposes to oxygen and fluorine by a [[Biology:Radical|radical]] mechanism.
:{{chem2|2 OF2 ->  O2  +  2 F2}}
{{chem2|OF2}} reacts with many metals to yield [[Chemistry:Oxide|oxide]]s and [[Chemistry:Fluoride|fluoride]]s. [[Chemistry:Nonmetal|Nonmetal]]s also react: [[Chemistry:Phosphorus|phosphorus]] reacts with {{chem2|OF2}} to form [[Chemistry:Phosphorus pentafluoride|{{chem2|PF5}}]] and {{chem2|POF3}}; [[Chemistry:Sulfur|sulfur]] gives [[Chemistry:Sulfur dioxide|{{chem2|SO2}}]] and [[Chemistry:Sulfur tetrafluoride|{{chem2|SF4}}]]; and unusually for a [[Chemistry:Noble gas|noble gas]], [[Chemistry:Xenon|xenon]] reacts (at elevated temperatures) yielding [[Chemistry:Xenon tetrafluoride|{{chem2|XeF4}}]] and xenon oxyfluorides.

Oxygen difluoride reacts very slowly with water to form [[Chemistry:Hydrofluoric acid|hydrofluoric acid]]:
:{{chem2|OF2 + H2O ->  2 HF + O2}}

It can oxidize sulphur dioxide to [[Chemistry:Sulfur trioxide|sulfur trioxide]] and elemental [[Chemistry:Fluorine|fluorine]]:
:{{chem2|OF2 + SO2 -> SO3 + F2}}
However, in the presence of UV radiation, the products are [[Chemistry:Sulfuryl fluoride|sulfuryl fluoride]] ({{chem2|SO2F2}}) and pyrosulfuryl fluoride ({{chem2|S2O5F2}}):
:{{chem2|OF2 + 2 SO2 -> S2O5F2}}

==Safety==
Oxygen difluoride is considered an unsafe gas due to its oxidizing properties. Hydrofluoric acid produced by the hydrolysis of {{chem2|OF2}} with water is highly corrosive and toxic, capable of causing [[Biology:Necrosis|necrosis]], leaching calcium from the bones and causing cardiovascular damage, among a host of other highly toxic effects.

==Popular culture==
In [[Biography:Robert L. Forward|Robert L. Forward]]'s science fiction novel ''Camelot 30K'', oxygen difluoride was used as a biochemical solvent by fictional life forms living in the solar system's [[Astronomy:Kuiper belt|Kuiper belt]]. While {{chem2|OF2}} would be a solid at 30{{nbsp}}K, the fictional alien lifeforms were described as endothermic, maintaining elevated body temperatures and liquid {{chem2|OF2}} blood by radiothermal heating.

==Notes==
{{notelist}}

==References==
{{Reflist|2}}

==External links==
* [https://web.archive.org/web/20060116134617/http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Fluoride and compounds fact sheet]
* [http://webbook.nist.gov/cgi/cbook.cgi?ID=C7783417 WebBook page for {{chem2|OF2}}]
* [https://www.cdc.gov/niosh/npg/npgd0475.html CDC - NIOSH Pocket Guide to Chemical Hazards]

{{Fluorides}}
{{Oxygen compounds}}
{{Fluorine compounds}}

[[Category:Rocket oxidizers]]

{{Sourceattribution|Oxygen difluoride}}