Chemistry Reference
In-Depth Information
CH
2
COOH
C
CH
2
COOBu
C
150
o
C
/ 10h
HO
COOH
+
3
BuOH
HO
COOBu
EPIC
CH
2
COOH
CH
2
COOBu
Scheme 13.11
200-250ºC/6h
C(CH
2
OH)
4
4RCOOH
+
C(CH
2
OOCR)
4
EPIC
Scheme 13.12
CH
3
O
COOH
140-145
°
C / 24h
130-163
°
C / 24h
O
2
: 50ml / min
O
2
: 50ml / min
CH
3
CH
3
Scheme 13.14
Scheme 13.13
alternative to Friedel-Crafts acylation/benzoylation
(see Scheme 13.14).
Envirocat EPAD can be used also in the oxidation
of aliphatic alcohols. The oxidation of the terminal
OH group of a polyethylene glycol chain to the cor-
responding aldehyde and acid is used in the manu-
facture of shampoo. This oxidation can be achieved
using conventional methods but results in large
volumes of toxic, acidic wastestreams. Envirocat
EPAD can catalyse this oxidation under mild reac-
tion conditions in the absence of solvent. The cata-
lyst is suspended in the neat substrate and warmed
to 110°C with air. Over approximately 30 h, 80%
conversion to a 50 : 50 mixture of the corresponding
aldehyde and carboxylic acid is observed (see
Scheme 13.15).
under an atmosphere of O
2
and several atmospheres
of pressure [27]. To operate a commercial process
using these reaction conditions requires highly
expensive plant equipment that is inert under these
highly corrosive reaction conditions. Large volumes
of corrosive, toxic waste are produced in isolating the
benzoic acid from the reaction mixture.
Envirocat EPAD was one of the first true heteroge-
nous catalysts for performing aerobic oxidations. The
oxidation is performed in a solvent-free environment
at atmospheric pressure, using O
2
as the oxidant. This
means that the only wastestream produced during
the reaction is water.
p
-Toluic acid, an agrochemical
intermediate, can be prepared selectively using
Envirocat EPAD. The reaction is performed at 140-
145°C over 24 h, using O
2
as the oxidant. Typical
yields for this process are around 30%, with a selec-
tivity of 93% for the toluic acid (see Scheme 13.13).
This catalyst also will catalyse the oxidation of
chloro- and bromotoluenes to their respective
benzoic acids.
Similar reaction conditions also can be used to
oxidise aromatic methylenes to produce acetophe-
nones and benzophenones [14,35,36], and this is an
8 Other Applications of Envirocat
Catalysts
The Envirocat range of catalysts was designed ini-
tially for a particular application, e.g. EPZG for
benzoylation, EPIC for high-temperature esterifica-
tion, etc. However, the clay-based reagents possess
Brønsted and Lewis acid sites to various degrees.
Over the last 10 years other researchers and compa-
