Chemistry Reference
In-Depth Information
Fig. 14.4
Heteropolymetallate-catalysed production of adipic and other diacids.
Scheme 14.13
industry has been as a replacement for phosgene in
the production of polyurethanes, which is a very
large market (4.7 ¥ 10
6
t year
-1
in 1990 growing to
7.7 ¥ 10
6
t year
-1
in 2000) [56]. However, replace-
ment of phosgene with dimethylcarbonate has been
considered too expensive.
A new, less-expensive commercial process for
dimethylcarbonate has been developed that proceeds
via CuCl-catalysed oxidative carbonylation of
methanol. Carbonylation is carried out at 120°C and
27 atm with oxygen as the terminal oxidant. The
selectivity for dimethylcarbonate production is high,
with CO
2
from CO combustion being the only side
product (Fig. 14.5) [57].
A disadvantage of this process is that it must be
run as a slurry and is highly corrosive, requiring
specialised equipment. Some recent attempts to
improve the reaction have been reported [58]. Other
reports indicate that dimethylcarbonate can be made
directly from the reaction of CO
2
and methanol [59]
