Triphosgene (bis(trichloromethyl) carbonate (BTC) is a chemical compound with the formula OC(OCCl3)2. It is used as a solid substitute for phosgene, which is a gas and diphosgene, which is a liquid.[5][6] Triphosgene is stable up to 200 °C.[7] Triphosgene is used in a variety of halogenation reactions.[8]
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Preferred IUPAC name
Bis(trichloromethyl) carbonate | |
Other names
BTC
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Identifiers | |
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3D model (JSmol)
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ChemSpider |
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ECHA InfoCard | 100.046.336 |
PubChem CID
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UNII |
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CompTox Dashboard (EPA)
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Properties | |
C3Cl6O3 | |
Molar mass | 296.748 g/mol |
Appearance | white solid |
Density | 1.780 g/cm3 |
Melting point | 80 °C (176 °F; 353 K) |
Boiling point | 206 °C (403 °F; 479 K) |
Reacts | |
Solubility | *soluble in dichloromethane[1] |
Hazards | |
GHS labelling: | |
[4] | |
Danger | |
H314, H330[4] | |
P260, P280, P284, P305+P351+P338, P310[4] | |
Safety data sheet (SDS) | SDS Triphosgene |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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This compound is commercially available. It is prepared by exhaustive free radical chlorination of dimethyl carbonate:[6]
Triphosgene can be easily recrystallized from hot hexanes.
Triphosgene is used as a reagent in organic synthesis as a source of CO2+. It behaves like phosgene, to which it cracks thermally:
Alcohols are converted to carbonates. Primary and secondary amines are converted to ureas and isocyanates.[6][7][9][10]
Triphosgene has been used to synthesize chlorides.[8] Some Alkyl chlorides are prepared by treating alcohols with a mixture of triphosgene and pyridine. Alkyl dichlorides and trichlorides can similarly be synthesized using triphosgene. Vinyl chlorides are synthesized from ketones using triphosgene and DMF to form a Vilsmeier reagent, followed by a ring opening by chloride ions. Aryl chlorides can also be produced using a Vilsmeier reagent from triphosgene and DMF.
Triphosgene's low vapor pressure makes it possible for it to reach concentrations that are considered toxicologically unsafe.[11] While several properties of triphosgene are not yet readily available, it is known that it is very toxic if inhaled. A toxic gas is emitted if it comes in contact with water.[12] There is a lack of information and variability regarding the proper handling of triphosgene. It is assumed to have the same risks as phosgene.[13][14]