Introduction
<P>The well-known NaNO
2 (mp 271 °C, d = 2.17) has multiple applications in organic synthesis but also in
medicine as a vasodilator, bronchodilator and antidote against cyanide and H
2S poisoning. It is produced in the human body from saliva and sodium nitrate to control
bacteria in the stomach.</P><P>The synthetic utilities of NaNO
2 have been extensively investigated in organic chemistry. Nitrosation of primary amines
with nitrous acid (generated in situ from sodium nitrite and a strong acid) leads
to diazonium salts. These salts are useful synthetic intermediates used in named reactions
like Sandmeyer, Balz-Schiemann,
[
1]
Pschorr,
[
2]
and Heck
[
3]
or in the manufacture of diazo dyes.
[
4]
NaNO
2 is also used in the synthesis of alkyl nitrites,
[
5]
reagents used for the synthesis of diazonium salts in non-aqueous media
[
6]
or for the diazotization of primary aliphatic amines
[
7]
in DMF.</P><P>NaNO
2 reacts with SO
2 and potassium hydrogen carbonate to afford potassium hydroxylaminedisulfonate salt,
which gives after oxidation nitrosodisulfonic acid dipotassium salt. This Fremy’s
salt is a useful reagent for the selective oxidation of phenols and aromatic amines
to quinones (the Teuber reaction).
[
8]
</P><P>Hydroxylamine hydrochloride is synthesized from NaNO
2 in a three-step procedure.
[
9]
</P>
