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Solvent-Free Benzylic Oxidations
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non-polar ones.33 The 4-nitrotoluene is more polar due to
the presence of nitro group as compared to toluene and
hence, more prone to microwave heating and thus, under-
goes reaction faster than toluene. Under thermal condi-
tions where polarity has no effect on the rate of reaction,
4-nitrotoluene undergoes reaction slower than toluene due
to the deactivating effect of nitro group. Thus, microwave
heating allows faster reaction and higher yields than oil-
bath heating.
(18) Varma, R. S.; Dahiya, R. Tetrahedron Lett. 1998, 39, 1307.
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In conclusion, we have developed a simple, safe and eco-
nomic method for oxidation of substituted toluenes, naph-
thalene, and tetralin. The procedure is environmentally
friendly and is a useful alternative to existing methods.
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(29) General Procedure: Substrate (1 mmol) and UHP (15
mmol) were added to a borosil beaker (50 mL). The mixture
was stirred properly and then irradiated in a microwave oven
for an appropriate time (Table 1) at 300 W (monitored by
TLC). On cooling at r.t., the product was extracted with
CH2Cl2 (3 × 15 mL). The combined methylene extracts were
washed with H2O and dried over anhyd Na2SO4. The product
obtained after removal of the solvent under reduced pressure
was crystallized from an appropriate solvent.
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Synlett 2004, No. 3, 531–533 © Thieme Stuttgart · New York