Chemistry Reference
In-Depth Information
An investigation of eight classes of catalysts (exchange resins, zirconium, tita-
nium, and tin homogeneous catalysts, Group VB and VIB compounds, alkali metal
silicates, zeolites, acidic resins, tertiary phosphine polymer catalysts) for DMC
production from EC is given in [700]. The relative performance advantages and
mechanistic pathways of these different classes of catalysts are compared and dis-
cussed.
The above presented process with CoYO as catalyst is employed in the produc-
tion of DPhC in 95% yield from EC [701]. It is a continuous process using a fixed
bed reactor at 130
C, a pressure of 9 kg cm
2
, and an LHSV of 3 h
1
.
Cat = CoYO
1. MeOH
O
O
+
OH
O
H
O
O
2. PhOH
O
O
DPhC
95 %
4.3.3.8
Carbon Oxides, CO, CO
2
, and MCO
3
Another route to DPhC, besides transesterification of DMC or EC with phenol as
in Section 4.3.3.7, is the oxidative carbonylation of phenol with carbon monoxide
(CO) and aerial oxygen, as catalyzed by a Pd dinuclear complex and a redox catalyst
[702, 703].
OH
O
2
O
+
CO
+
2
H
2
O
Pd
2
(Ph
3
PPy)
2
Cl
2
redox catalyst
NH
4
Cl, 100°C
O
O
DPhC
The reaction proceeds smoothly on Pd dinuclear complexes bridged by the pyri-
dylphosphine ligand, i.e. [Pd
2
(Ph
2
Ppy)
2
X
2
], in the presence of a redox catalyst,
ammonium halide, CO, and air at 100
C; the TOF reaches 19.21 (mol-DPhC/
mol-Pd h).
Carbon dioxide (CO
2
) can be reacted with alcohols under various conditions to
form dialkyl carbonates. One of the most attractive synthetic goals starting from
CO
2
is DMC. An approach is the reaction of dehydrated derivatives of methanol
(ortho ester and acetals 978) with supercritical CO
2
[704-706].
978
DMC
979
supercritical
O
O
CO
2
O
O
+
R
R
O
O
R
R
R
2
Sn(OMe)
2
cat.
+ 2 MeOH
- H
2
O
