Rate constants of oxidation of thioanisole, PhSMe, by H2O2 mediated by tetraperoxomolybdate dianion, Mo(O2)42- , are almost unaffected by addition of hexan-1-ol or octan-1-ol to micellized cetylpyridinium chloride, CPyCl, although these hydrophobic alcohols should perturb the micellar interfacial region. The equilibrium between tri- and tetraperoxomolybdates and rates of their interconversion are not very sensitive to addition of these alcohols to CPyCl micelles. Micellar binding of octanol is much stronger than that of hexanol, but the two alcohols have similar effects upon rates and equilibria in CPyCl. These results differ from those for micellar-mediated reactions of hydrophilic anionic nucleophiles which are inhibited by hydrophobic solutes due to decreased anion binding and an increased volume of the micellar pseudophase. The 1H NMR spectra of CPyCl and PhSMe, with and without octanol, show that the micellar location of PhSMe is insensitive to added octanol.
Oxidation of Thioanisole by Peroxomolybdate in Alcohol-Modified Micelles of Cetylpyridinium Chloride
CHIARINI, MARCO
2002-01-01
Abstract
Rate constants of oxidation of thioanisole, PhSMe, by H2O2 mediated by tetraperoxomolybdate dianion, Mo(O2)42- , are almost unaffected by addition of hexan-1-ol or octan-1-ol to micellized cetylpyridinium chloride, CPyCl, although these hydrophobic alcohols should perturb the micellar interfacial region. The equilibrium between tri- and tetraperoxomolybdates and rates of their interconversion are not very sensitive to addition of these alcohols to CPyCl micelles. Micellar binding of octanol is much stronger than that of hexanol, but the two alcohols have similar effects upon rates and equilibria in CPyCl. These results differ from those for micellar-mediated reactions of hydrophilic anionic nucleophiles which are inhibited by hydrophobic solutes due to decreased anion binding and an increased volume of the micellar pseudophase. The 1H NMR spectra of CPyCl and PhSMe, with and without octanol, show that the micellar location of PhSMe is insensitive to added octanol.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
