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on a thermomorphic catalyst comprising PNIPAAm. Forma-
tion of a stable emulsion, derived from hydrophobic PNI-
PAAm at high temperature, raises the catalytic activity in the
oxidation of alcohols with hydrogen peroxide. Moreover, the
catalyst is easily recovered and reused. The results described
herein highlight the potential use of PNIPAAm in the field of
organic synthesis. Further investigation into the catalytic
properties of temperature-responsive catalysts are currently
in progress.
Experimental Section
General procedure for the catalytic reaction: A mixture of 1b (80 mg,
0.01 mmol) and 2 (10 mmol) in 10% aqH 2O2 (4.5 mL, 15 mmol) was
heated to 908C and stirred for 6 h. After the reaction mixture had
been allowed to cool to room temperature, Et2O (2.5–5 mL) was
added and this mixture stirred for 5–10 min. The organic and aqueous
phases were removed, and recovered 1b was washed with ether and
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chromatography to give the pure products of 3. Recovered 1b was
dried under vacuum for 12 h and reused for subsequent catalytic
experiments.
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Received: February 16, 2005
Revised: May 2, 2005
Published online: June 21, 2005
Keywords: green chemistry · micelles · oxidation · polymers ·
.
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Angew. Chem. Int. Ed. 2005, 44, 4536 –4538