A simple method for the iodination of activated arenes, using molecular iodine and
sodium peroxodisulfate as the oxidant, is presented. The reaction is conducted in
the presence of catalytic amounts of tetramethylammonium iodide as a phase-transfer
catalyst in acetonitrile. For non-polar substances, which are not soluble in pure
acetonitrile such as calix[4]arenes bearing long alkyl chains, a modified reaction
is introduced. In this case the phase-transfer catalyst is changed to methyltriphenylphosphonium
peroxodisulfate. Chloroform as a cosolvent mediates solubility. Furthermore, we show
that the slightly basic conditions obtained upon the addition of sodium bicarbonate
have a beneficial effect on the yield.
calixarenes - phase-transfer catalysis - iodination - oxidative halogenation - peroxides