Introduction
<P>Barium hydroxide is a highly valuable reagent, in organic synthesis,
due to the availability of the hydroxide ion in solution, the size
of the barium counter ion, and for some of its forms, its microcrystalline
structure
[
1]
when it is insoluble
or partly insoluble in the medium. Ba(OH)
2·8H
2O is
the most common form and is commercially available.
[
2]
Activated barium hydroxide
Ba(OH)
2 (C-200), [Ba(OH)
2·H
2O] is
obtained by heating commercial Ba(OH)
2·8H
2O
in an oven at 200 °C for 3 h and powdering the
resulting product.
[
3]
Barium
hydroxide reacts as a base
[
4-7]
or
as a nucleophile,
[
8]
[
9]
in homogenous
[
9]
[
10]
or heterogeneous conditions.
[
1]
[
4]
[
7]
[
11]
Barium
hydroxide was revealed to be efficient in deacylations,
[
12]
in Michael addition,
[
3]
in aldol or aldol-type
condensation,
[
13]
in
Wittig-Horner reactions,
[
11]
[
14]
[
15]
in
Claisen-Schmidt reactions,
[
16]
in Canizzaro
reactions,
[
6]
and in Suzuki coupling.
[
5]
[
10]
[
17]
</P>