Perfluoroisobutene

Perfluoroisobutene (PFIB) is the perfluorocarbon with the formula (CF₃)₂C=CF₂. Classified as a perfluoroalkene, it is the fluorinated counterpart of the hydrocarbon isobutene. This colorless gas is notable for its high toxicity.^[1]

Perfluoroisobutene

Names
Preferred IUPAC name 1,1,3,3,3-Pentafluoro-2-(trifluoromethyl)prop-1-ene
Other names Perfluoroisobutene, Perfluoroisobutylene, Octafluoroisobutylene, Octafluoro-sec-butene, PFIB
Identifiers
CAS Number	382-21-8 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL4634291
ChemSpider	55060 Y
ECHA InfoCard	100.108.743
EC Number	609-533-9
PubChem CID	61109
RTECS number	UD1800000
UNII	1J9BGS6NTY Y
CompTox Dashboard (EPA)	DTXSID4073176
InChI InChI=1S/C4F8/c5-2(6)1(3(7,8)9)4(10,11)12 N Key: DAFIBNSJXIGBQB-UHFFFAOYSA-N N InChI=1/C4F8/c5-2(6)1(3(7,8)9)4(10,11)12 Key: DAFIBNSJXIGBQB-UHFFFAOYAF
SMILES FC(F)=C(C(F)(F)F)C(F)(F)F
Properties
Chemical formula	C4F8
Molar mass	200.030 g/mol
Appearance	colorless gas
Density	8.2 g/l
Melting point	−130 °C (−202 °F; 143 K)
Boiling point	7.0 °C (44.6 °F; 280.1 K)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H330, H370
Precautionary statements	P260, P264, P270, P271, P284, P304+P340, P307+P311, P310, P320, P321, P403+P233, P405, 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

Production and reactions

PFIB is one product of pyrolysis of polytetrafluoroethylene (PTFE).^[2] Tetrafluoroethylene thermally dimerizes to octafluorocyclobutane, which above 600 °C degrades to hexafluoropropylene and PFIB.^[1]

Perfluoroisobutene is highly reactive toward nucleophiles, e.g. methanol.^[1] It also forms addition compounds with thiols, and it is this reactivity that may be related to its toxicity.^[3] It hydrolyzes readily to give the relatively innocuous (CF₃)₂CHCO₂H, which readily decarboxylates to give hexafluoropropane.^{[citation needed]}

Oxidation of HFIB with potassium permanganate gives hexafluoroacetone.^[4]

Safety

Perfluoroisobutene is highly toxic with an LCt = 880 mg⋅min⋅m⁻³ (mice).^[3] It is a Schedule 2 substance of the Chemical Weapons Convention. Its toxicity is comparable to that of phosgene.^[1]