Triphosgene

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]

Triphosgene

Names
Preferred IUPAC name Bis(trichloromethyl) carbonate
Other names BTC
Identifiers
CAS Number	32315-10-9 Y
3D model (JSmol)	Interactive image
ChemSpider	85216 Y
ECHA InfoCard	100.046.336
PubChem CID	94429
UNII	2C0677Q3B2 Y
CompTox Dashboard (EPA)	DTXSID00865631
InChI InChI=1S/C3Cl6O3/c4-2(5,6)11-1(10)12-3(7,8)9 Y Key: UCPYLLCMEDAXFR-UHFFFAOYSA-N Y InChI=1/C3Cl6O3/c4-2(5,6)11-1(10)12-3(7,8)9 Key: UCPYLLCMEDAXFR-UHFFFAOYAA
SMILES ClC(Cl)(Cl)OC(=O)OC(Cl)(Cl)Cl
Properties
Chemical formula	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)
Solubility in water	Reacts
Solubility	*soluble in dichloromethane[1] soluble in THF[2] soluble in toluene[3]
Hazards
GHS labelling:
Pictograms	[4]
Signal word	Danger
Hazard statements	H314, H330[4]
Precautionary statements	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). N verify (what is YN ?) Infobox references

Preparation

This compound is commercially available. It is prepared by exhaustive free radical chlorination of dimethyl carbonate:^[6]

CH₃OCO₂CH₃ + 6 Cl₂ → CCl₃OCO₂CCl₃ + 6 HCl

Triphosgene can be easily recrystallized from hot hexanes.

Uses

Triphosgene is used as a reagent in organic synthesis as a source of CO²⁺. It behaves like phosgene, to which it cracks thermally:

OC(OCCl₃)₂ ⇌ 3 OCCl₂

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.

Safety

The vapor pressure of Triphosgene is sufficiently high 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]

See also

• Phosgene
• Diphosgene