Hexafluorothioacetone
Chemical compound
From Wikipedia, the free encyclopedia
Hexafluorothioacetone is an organic perfluoro thione compound with formula CF3CSCF3. At standard conditions it is a blue gas.[2]
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| Names | |
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| Preferred IUPAC name
1,1,1,3,3,3-Hexafluoropropane-2-thione | |
| Other names
Perfluorothioacetone | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
PubChem CID |
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| Properties | |
| C3F6S | |
| Molar mass | 182.08 g·molâ1 |
| Appearance | blue gas |
| Boiling point | 8 °C (46 °F; 281 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production
Hexafluorothioacetone was first produced by Middleton in 1961 by boiling bis-(perfluoroisopropyl)mercury with sulfur.
Properties
Hexafluorothioacetone boils at 8 °C.[3] Below this it is a blue liquid.[2]
Colour
The blue colour is due to absorption in the visible light range with bands at 800â675 nm and 725â400 nm. These bands are due to T1âS0 and S1âS0 transitions.[2] There is also a strong absorption in ultraviolet around 230-190 nm.[2]
Reactions
Hexafluorothioacetone acts more like a true thiocarbonyl (C=S) than many other thiocarbonyl compounds, because it is not able to form thioenol compounds (=C-S-H), and the sulfur is not in a negative ionized state (C-Sâ).[4] Hexafluorothioacetone is not attacked by water or oxygen at standard conditions as are many other thiocarbonyls.[2]
Bases trigger the formation of a dimer 2,2,4,4-tetrakis-(trifluoromethyl)-1,3-dithietane.[2] Bases includes amines.[4]
The dimer can be heated to regenerate the hexafluorothioacetone monomer.[2]
The dimer is also produced in a reaction with hexafluoropropene and sulfur with some potassium fluoride.[2][5]
Hexafluorothioacetone reacts with bisulfite to form a Bunte salt CH(CF3)2SSO2â.[4]
Thiols reacting with hexafluorothioacetone yield disulfides or a dithiohemiketal:
- R-SH + C(CF3)2S â R-S-S-CH(CF3)2.[4]
- R-SH + C(CF3)2S â RSC(CF3)2SH (for example in methanethiol or ethanethiol).[4]
With mercaptoacetic acid, instead of a thiohemiketal, water elimination yields a ring shaped molecule called a dithiolanone -CH2C(O)SC(CF3)2S- (2,2-di(trifluoromethyl)-1,3-dithiolan-4-one).[4] Aqueous hydrogen chloride results in the formation of a dimeric disulfide CH(CF3)2SSC(CF3)2Cl.[4] Hydrogen bromide with water yields the similar CH(CF3)2SSC(CF3)2Br.[4] Dry hydrogen iodide does something different and reduces the sulfur making CH(CF3)2SH. Wet hydrogen iodide only reduces to a disulfide CH(CF3)2SSC(CF3)2H. Strong organic acids add water to yield a disulfide compound CH(CF3)2SSC(CF3)2OH.[4]
Chlorine and bromine add to hexafluorothioacetone to make CCl(CF3)2SCl and CBr(CF3)2SBr.[4]
With diazomethane hexafluorothioacetone produces 2,2,5,5-tetrakis(trifluoromethyl)-l,3-dithiolane, another substituted dithiolane.[4] Diphenyldiazoniethane reacts to form a three membered ring called a thiirane (di-2,2-trifluoromethyl-di-3,3-phenyl-thiirane)
Trialkylphosphites (P(OR)3) react to make a trialkoxybis(trifluoromethyl)methylenephosphorane (RO)3P=C(CF3)2 and a thiophosphate (RO)3PS.[4]
Hexafluorothioacetone can act as a ligand on nickel.[6]
Hexafluorothioacetone is highly reactive to alkenes and dienes combining via addition reactions. With butadiene it reacts even as low as -78 °C to yield 2,2-bis-(trifluoromethyl)-3,6-dihydro-2H-l-thiapyran.[7]
See also
- Hexafluoroacetone
- Trifluoronitrosomethane â Toxic gaseous compound
