1374
R. Suthakaran et al. / Tetrahedron 57 (2001) 1369±1374
prepared by the acid hydrolysis33,34 of tetrapotassium
peroxodiphosphate (FMC Corporation) which was
employed after repeated recrystallization from methanol±
water mixture. Doubly distilled water was used throughout,
the second distillation being from permanganate. Acetic
acid was puri®ed by the method of Orton and Brad®eld.35
All other chemicals used were of AR grade.
Srinivasan, C. Proc. Indian Acad. Sci. (Chem. Sci.) 1991,
103, 637.
9. Chellamani, A.; Kulanthaipandi, P.; Rajagopal, S. J. Org.
Chem. 1999, 64, 2232.
10. Srinivasan, C.; Kuthalingam, P.; Arumugam, N. Int. J. Chem.
Kinet. 1982, 14, 1139.
11. Rajagopal, S. Ph.D. Thesis, Madurai Kamaraj University,
1984.
12. Ogata, Y.; Urasaki, I.; Nagura, K.; Satomi, N. Tetrahedron
1974, 30, 3021.
3.2. Kinetic measurement
13. Ogata, Y.; Tomizawa, K.; Ikeda, T. J. Org. Chem. 1978, 43,
2417.
The kinetic runs of oxidation of aryl methyl sulphoxides
with PMPA were carried out in 50% acetic acid±50%
water (v/v) under pseudo ®rst-order conditions with a
substrate:oxidant ratio of at least 10:1. The studies with
4,40-disubstituted diphenyl sulphoxides were carried out in
80% acetic acid±20% water (v/v) due to their poor solu-
bility in 50% aqueous acetic acid medium. The ionic
strength of the medium was maintained with sodium
perchlorate. Reactions were followed by measuring the
disappearance of PMPA. Aliquots withdrawn at appropriate
time intervals were treated with 1 M sodium hydroxide
solution to maintain the pH of the medium between 4 and
5, and then ®ve drops of ammonium molybdate were added
(to avoid the diffuse end point due to the presence of 2±3%
H2O2 formed during the course of hydrolysis) and estimated
by the usual iodometric procedure.
14. Ogata, Y.; Tomizawa, K.; Ikeda, T. J. Org. Chem. 1979, 44,
2362.
15. Panigrahi, G. P.; Panda, R. Bull. Chem. Soc. Jpn. 1979, 52,
3084.
16. Ogata, Y.; Sawaki, Y.; Tsukamoto, Y. Bull. Chem. Soc. Jpn.
1981, 54, 2061.
17. Panigrahi, G. P.; Panda, R. Bull. Chem. Soc. Jpn. 1980, 53,
2366.
18. Panigrahi, G. P.; Panda, R. Int. J. Chem. Kinet. 1980, 12, 491.
19. Viswamurthy, R.; Maruthamuthu, P. Oxidation Commun.
1981, 2, 37.
20. Panda, A. K.; Mahapatro, S. N.; Panigrahi, G. P. J. Org. Chem.
1981, 46, 4000.
21. Panigrahi, G. P.; Panda, R. Bull. Chem. Soc. Jpn. 1981, 54,
1554.
22. Mahapatro, S. N.; Panda, A. K.; Panigrahi, G. P. Bull. Chem.
Soc. Jpn. 1981, 54, 2507.
3.3. Product analysis
23. Panigrahi, G. P.; Nayak, R. N. Indian J. Chem. 1982, 21A,
361.
The reaction mixture from an actual kinetic run was neutra-
lized with a strong solution of sodium carbonate and
extracted with chloroform. Removal of the solvent gave
solid product. On the basis of mp and TLC, methyl phenyl
sulphone and diphenyl sulphone were identi®ed as ®nal
products in the oxidation of MPSO and DPSO, respectively.
24. Srinivasan, C.; Chellamani, A.; Rajagopal, S. J. Org. Chem.
1985, 50, 1201.
25. Srinivasan, C.; Rajagopal, S.; Chellamani, A. J. Chem. Soc.,
Perkin Trans. 2 1990, 1839.
26. Gould, E. S. Mechanism and Structure in Organic Chemistry;
Holt, Rinehart & Winston: New York, 1964.
27. Peterson, R. C.; Markgraff, J. H.; Ross, S. D. J. Am. Chem.
Soc. 1961, 83, 3819.
Acknowledgements
28. Battaglia, C. J.; Edwards, J. O. Inorg. Chem. 1965, 4, 552.
29. Peroxide Reaction Mechanisms, Edwards, J. O., Ed.; Inter-
science: New York, 1960; pp. 67±106.
R. S. thanks Madurai Kamaraj University for the award of a
Research Fellowship.
30. Behrman, E. J.; Edwards, J. O. In Prog. Phys. Org. Chem.,
Streitwiesser, A., Taft, R. W., Eds.; Interscience: New York,
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