66
B. S. Chhikara et al.
LETTER
(5) (a) Zhao, H.; Malhotra, S. V. Aldrichimica Acta 2002, 35,
75. (b) Dupont, J.; De Souza, R. F.; Suarez, P. A. Z. Chem.
Rev. 2002, 102, 3667. (c) Wasserscheid, P.; Keim, W.
Angew. Chem. Int. Ed. 2000, 39, 3772. (d) Welton, T.
Chem. Rev. 1999, 99, 2071. (e) Holbrey, J. D.; Seddon, K.
R. Clean Prod. Process. B 1999, 1, 232.
(6) Qiuo, K.; Deng, Y. J. Mol. Catal. A: Chem. 2001, 171, 81.
(7) Huang, J.; Jiang, T.; Han, B.; Chang, Y.; Zhao, G.; Wu, W.
Chem. Commun. 2003, 1654.
In conclusion, we have developed a simple and efficient
protocol for the oxidation of variety of benzylic and ali-
phatic secondary alcohol by hydrogen peroxide catalyzed
by a new catalyst 1-methyl-3-butylimidazolium decatung-
state [bmim][W10O23] in ionic liquid [bmim][BF4]. This
oxidation method shares the advantage of mild reaction
condition, easy recovery of the catalytic system, excellent
yield of the products, and ready separation of the products
and recycling of the catalytic system without much de-
creasing the yield of the product.
(8) Xu, L.; Chen, W.; Xiao, J. Organometallics 2000, 19, 1123.
(9) Yadav, J. S.; Reddy, B. V. S.; Gayathari, K. U.; Prasad, A.
R. Synthesis 2002, 2537.
(10) Mathews, C. J.; Smith, P. J.; Welton, T. Chem. Commun.
2000, 1249.
Acknowledgment
(11) (a) Chauhan, S. M. S.; Kumar, A.; Srinivas, K. A. Chem.
Commun. 2003, 2348. (b) Srinivas, K. A.; Kumar, A.;
Chauhan, S. M. S. Chem. Commun. 2002, 2456.
(12) Handy, S. T.; Zhang, X. Org. Lett. 2001, 3, 233.
(13) (a) Chhikara, B. S.; Mishra, A. K.; Tandon, V. Heterocyles
2004, 1057. (b) Kumar, A.; Jain, N.; Chauhan, S. M. S.
Synth. Commun. 2004, 34, 2835. (c) Chhikara, B. S.;
Tandon, V. Tetrahedron Lett. 2004, accepted for publication.
(14) Chemseddine, A.; Sanchez, C.; Livage, J.; Launay, J. P.;
Fournier, M. Inorg. Chem. 1984, 23, 2609.
(15) Synthesis of Catalyst [bmim]4[W10O23]: The boiling
solutions of Na2WO4·2H2O (16 g) in 100 mL H2O and 35 mL
of 3 M HCl were mixed in a Erlenmeyer flask and further
heated for 5 min to get yellow solution. To this was added 1-
methyl-3-butylimidazolium bromide [bmim][Br] (4.4 g) in
50 mL H2O with stirring. A puff greenish white precipitate
separates out instantly. Washed the solid with H2O
thoroughly and then with MeOH (50 mL) and Et2O (50 mL).
The solid was dried under air at r.t. to obtain puff white
product.
(16) Representative Procedure for the Oxidation of Alcohols:
Pre-saturated catalyst [bmim]4[W10O23] (100 mg) was
dissolved in [bmim][BF4] ionic liquid (2 mL) by heating.
Then added diphenyl carbinol (184 mg, 10 mmol) and
heated the reaction mixture to 90 °C on oil bath, followed by
drop-wise addition of hydrogen peroxide 30% solution (172
mL) with fast stirring. Then, 10 mL of reaction mixture were
taken out at different time interval, extracted with Et2O and
monitored by TLC and GC. The conversion percentage and
purity of product was checked by gas chromatography
(Table 2). On completion of reaction, the reaction mixture
was cooled to r.t. and extracted with Et2O (3 × 3 mL).
Finally, the solvent was evaporated under reduced pressure
to obtain diphenyl ketone (175 mg, 96% yield).
The author BSC is thankful to Council for Scientific and Industrial
Research (CSIR), New Delhi for providing senior research fel-
lowship (SRF).
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Synlett 2005, No. 1, 63–66 © Thieme Stuttgart · New York