Diphosgene

Diphosgene
Names


IUPAC name Diphosgene
Other names trichloromethyl chloroformate
Identifiers
CAS Number	503-38-8^Y
3D model (Jmol)	Interactive image
ChemSpider	21154424^Y
ECHA InfoCard	100.007.242
RTECS number	LQ7350000
InChI InChI=1S/C2Cl4O2/c3-1(7)8-2(4,5)6^Y Key: HCUYBXPSSCRKRF-UHFFFAOYSA-N^Y InChI=1/C2Cl4O2/c3-1(7)8-2(4,5)6 Key: HCUYBXPSSCRKRF-UHFFFAOYAO
SMILES ClC(=O)OC(Cl)(Cl)Cl
Properties
Chemical formula	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)
Solubility in water	insol.
Hazards
Main hazards	toxic
R-phrases	26/28-34
S-phrases	26-28-36/37/39-45
Flash point	32 °C (90 °F; 305 K)
Related compounds
Related compounds	COCl₂, Cl₂
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y (what is ^YN ?)
Infobox references

Diphosgene is a chemical compound with the formula ClCO₂CCl₃. This colorless liquid is a valuable reagent in the synthesis of organic compounds. Diphosgene is related to phosgene and has comparable toxicity, but is more conveniently handled because it is a liquid, whereas phosgene is a gas.

Diphosgene is prepared by radical chlorination of methyl chloroformate under UV light:

Another method is the radical chlorination of methyl formate:

Diphosgene converts to phosgene upon heating or upon catalysis with charcoal. It is thus useful for reactions traditionally relying on phosgene. For example, it convert amines into isocyanates, secondary amines into carbamoyl chlorides, carboxylic acids into acid chlorides, and formamides into isocyanides. Diphosgene serves as a source of two equivalents of phosgene:

With α-amino acids diphosgene gives the acid chloride-isocyanates, OCNCHRCOCl, or N-carboxy-amino acid anhydrides depending on the conditions.

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 a pulmonary agent for chemical warfare, a few months after the first use of phosgene. It was used as a poison gas in artillery shells by Germany during World War I. The first recorded battlefield use was in May 1916. Diphosgene was developed because the vapors could destroy the filters in gas masks in use at the time.

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Wikipedia