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| Names | |
|---|---|
| Preferred IUPAC name Trichloromethyl carbonochloridate | |
| Other names Trichloromethyl chloroformate, surpalite | |
| Identifiers | |
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3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.007.242 |
| EC Number |
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| RTECS number |
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| UNII | |
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| Properties | |
| C2Cl4O2 | |
| Molar mass | 197.82 g/mol |
| Appearance | liquid at room temperature |
| Density | 1.65 g/cm3 |
| Melting point | −57 °C (−71 °F; 216 K) |
| Boiling point | 128 °C (262 °F; 401 K) |
| insoluble, reacts | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | highly toxic, maybe corrosive; asphyxiant |
| GHS labelling: | |
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| Danger | |
| H300,H301,H314,H330 | |
| P260,P264,P270,P271,P280,P284,P301+P310,P301+P330+P331,P303+P361+P353,P304+P340,P305+P351+P338,P310,P320,P321,P330,P363,P403+P233,P405,P501 | |
| Flash point | 32 °C (90 °F; 305 K) |
| Related compounds | |
Related compounds | COCl2, Cl2 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Diphosgene is an organicchemical compound with the formula ClCO2CCl3. This colorless liquid is a valuable reagent in thesynthesis of organiccompounds. Diphosgene is related tophosgene and has comparabletoxicity, but is more conveniently handled because it is a liquid, whereas phosgene is a gas.
Diphosgene is prepared byradical chlorination ofmethyl chloroformate underUV light:[1]
Another method is the radical chlorination of methyl formate:[2]
Diphosgene converts to phosgene upon heating or uponcatalysis withcharcoal. It is thus useful for reactions traditionally relying on phosgene. For example, it convertamines intoisocyanates, secondary amines intocarbamoyl chlorides,carboxylic acids intoacid chlorides, andformamides intoisocyanides. Diphosgene serves as a source of two equivalents of phosgene:
With α-amino acids diphosgene gives the acid chloride-isocyanates, OCNCHRCOCl, orN-carboxy-amino acid anhydrides depending on the conditions.[3]
It hydrolyzes to release HCl in humid air.
Diphosgene is used in some laboratory preparations because it is easier to handle than phosgene.
Diphosgene was originally developed as apulmonary agent forchemical warfare, a few months after the first use of phosgene. It was used as a poison gas inartillery shells byGermany duringWorld War I. The first recorded battlefield use was in May 1916.[4] German forces preferred diphosgene, liquid at room temperature, because it was easier to handle than gaseous phosgene.[5] Diphosgene was developed because the vapors could destroy the filters of thegas masks in use at the time.
Diphosgene has a relatively highvapor pressure of 10 mm Hg (1.3 kPa) at 20 °C and decomposes tophosgene around 300 °C. Exposure to diphosgene is similar in hazard to phosgene.
