Octafluorocyclobutane, or perfluorocyclobutane, C₄F₈, is an organofluorine compound which enjoys several niche applications. Octafluorocyclobutane is a colourless gas and shipped as a liquefied gas. It is the perfluorinated analogue of cyclobutane whereby all C–H bonds are replaced with C–F bonds.

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Octafluorocyclobutane

Names
Preferred IUPAC name Octafluorocyclobutane
Other names Freon-C-318, perfluorocyclobutane
Identifiers
CAS Number	115-25-3 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1909266
ChEBI	CHEBI:31007 Y
ChEMBL	ChEMBL444147 Y
ChemSpider	13846040 Y
ECHA InfoCard	100.003.705
EC Number	204-075-2
E number	E946 (glazing agents, ...)
Gmelin Reference	131113
PubChem CID	8263
UNII	V9P1D0A21K Y
CompTox Dashboard (EPA)	DTXSID9041811
InChI InChI=1S/C4F8/c5-1(6)2(7,8)4(11,12)3(1,9)10 N Key: BCCOBQSFUDVTJQ-UHFFFAOYSA-N N InChI=1/C4F8/c5-1(6)2(7,8)4(11,12)3(1,9)10 Key: BCCOBQSFUDVTJQ-UHFFFAOYAW
SMILES C1(C(C(C1(F)F)(F)F)(F)F)(F)F
Properties
Chemical formula	C4F8
Molar mass	200.03 g/mol
Appearance	colourless gas
Density	1.637 g/cm3 at −5.8 °C (liquid) 9.97 kg/m3 at −6 °C and 1 atm (gas) 8.82 kg/m3 15 °C and 1 atm (gas)
Melting point	−40.1 °C (−40.2 °F; 233.1 K)
Boiling point	−5.8 °C (21.6 °F; 267.3 K)
Solubility in water	0.016 vol/vol (1.013 bar and 20 °C)
Viscosity	109e-6 Poise (1.013 bar and 0 °C)
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H280, H411
Precautionary statements	P273, P391, P410+P403, P501
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

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Octafluorocyclobutane is produced by the dimerization of tetrafluoroethylene and the reductive coupling of 1,2-dichloro-1,1,2,2-tetrafluoroethane.^[1]

In the production of semiconductor materials and devices, octafluorocyclobutane serves as a deposition gas and etchant.^[2] It has also been investigated as a refrigerant in specialised applications, as a replacement for ozone depleting chlorofluorocarbon refrigerants. Exploiting its volatility and chemical inertness, octafluorocyclobutane may be found in some aerosolized foods. It is listed by the Codex Alimentarius under number 946 (E946 for EU). It is investigated as a possible replacement for sulfur hexafluoride as a dielectric gas.

• PFC-318 measured by the Advanced Global Atmospheric Gases Experiment (AGAGE) in the lower atmosphere (troposphere) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.