Introduction <P>Sodium chlorite (NaClO
2 ) is a highly efficient bleaching agent
and oxidative disinfectant, widely applied in bleaching of textile,
fiber, pulp and paper. In addition, this substance is employed to
whiten sugar, starch, grease, ointment and wax.
[
¹ ]
</P><P>In organic synthesis, NaClO
2 is an inexpensive and
versatile reagent, which has been explored for preparations of carboxylic
acids from aldehydes
[
² ]
or
primary alcohols
[
³ ]
, amides
from imines,
[
4 ]
enones from allylic
and benzylic substrates,
[
5 ]
epoxides
from olefins
[
6 ]
and γ-hydroxybutenolides
from furans.
[
7 ]
Moreover, this reagent
has also been employed in the oxidative deprotection of 1,3-dithiane groups,
[
8 ]
as oxidant and hydroxyl ion pump
in osmium-catalyzed asymmetric dihydroxilation
[
9 ]
as
well as in the iodination of aromatic and heterocyclic
compounds.
[
¹0 ]
</P>
Preparation <P>The production of NaClO
2 using a reducing agent is
the most common methodology used to manufacture this substance.
This process consists in the preparation of chlorine dioxide by
reacting sodium chlorate in sulfuric acid (Scheme
[
¹ ]
a) and, then the reaction
of chlorine dioxide with a reducing agent in sodium hydroxide solution (Scheme
[
¹ ]
b). The chlorine dioxide
generation is generally based on the reduction of sodium chlorate
by reducing agents, such as sulfur dioxide, hydrochloric acid, sodium chloride,
methanol and hydrogen peroxide.
[
¹ ]
</P>
Scheme 1
