|
The United States, Western Europe and Asia are currently the major producing
and consuming regions for phosgene, primarily consumed captively to manufacture
p,p'-methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI)
and polycarbonate resins.
In 2006, global production/demand was estimated at over 7 million metric tons.
About 75–80% of global phosgene is consumed for isocyanates, 18% for
polycarbonates and about 5% for other fine chemicals. Fine chemical applications
are further broken down to 50% for intermediates, 25% for agrochemicals, 20%
for pharmaceuticals and 5% for monomers and coloring agents.
The following pie chart shows world consumption of phosgene:
Very little active worldwide trade takes place for phosgene; most phosgene
is consumed in the plant locations where it is produced. Small volumes of phosgene
are transported by tanks to use in other locations.
Phosgene (carbonyl chloride), an extremely poisonous and reactive gas, was
discovered in 1812 by John Davy, who obtained phosgene by the action of light
on a mixture of chlorine and carbon monoxide. Phosgene was produced for use
during World War I as a warfare agent because of its high degree of toxicity.
Phosgene is currently used to produce isocyanates (intermediates for polyurethane
resins and pesticides), polycarbonates, acid chlorides, chloroformates, chlorocarbamates
and organic carbonates. Phosgene is not a very efficient intermediate; although
yields are high, in most of its uses only about 30% of its weight ends up in
the derivative.
|
