Chemistry Reference
In-Depth Information
Fuel additive
Surfactants
and emulsifiers
R
O
OH
O
O
HO
O
R
R
R
d
n
9
r
3
n
g
|
0
OH
R = H or tert-BUTYL
HO
OH
R = ALKYL CHAIN
MONO, DI and
TRI-tert-BUTYL
GLYCEROL
GLYCEROL
ALKYL GLYCEROL
d
y
y
f
n
n
3
.
Polymer crosslinker,
lubricant precursor
Precursor for emulsifies
and antifogging agents
HO
OH
OH
OH
O
O
HO
OH
HO
OH
2,2
′
-DIGLYCEROL
1,1
′
-DIGLYCEROL
Scheme 6.10
Oligomerisations and etherifications of glycerol with Bro¨ nsted-acid
catalyst.
OR
O
OR
OH
OH
OH
OR
O
HO
OH
O
n
OR
+
RO
Solid base catalyst
RO
+
OR
RO
O
n = 2-5
T > 200, 2-24 h.
R = H, n
′
OLIGOGLYCEROL ETHERS
AND ISOMERS
(n
GLYCEROL
′
= 0-4)
Scheme 6.11
General scheme for the oligomerisation of glycerol.
OH
OH
OH
HO
O
HO
1) NaOH, 90-150 °C
2) DMST
3) Vacuum distillation
1-O-METHYL-GLYCEROL
GLYCEROL
Scheme 6.12
Mechanism for the selective production of linear oligoglycerols.
Examples of the synthesis of ethyl glycerol with various solid acid catalysts
161
have been described, as well as other etherification processes using grafted
silicas,
162
and zeolites.
163
The production of methyl glycerols from biodiesel
glycerine seems interesting, due to the in situ ether generation of two major
components of glycerine (glycerol and methanol).
6.6.7.1 Selectivity and Mechanism
CaO (and also MgO to a lesser extent) is a good example of a selective catalyst
for the formation of linear oligoglycerols. The selectivity of the process might
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