*** Welcome to piglix ***

Diphosgene

Diphosgene
Diphosgene
Diphosgene
Names
IUPAC name
Diphosgene
Other names
trichloromethyl chloroformate
Identifiers
503-38-8 YesY
3D model (Jmol) Interactive image
ChemSpider 21154424 YesY
ECHA InfoCard 100.007.242
RTECS number LQ7350000
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)
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).
YesY  (what is YesYN ?)
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.


...
Wikipedia

...