Oxidation-kinetics of balsalazide
1663
oxidation process, values of K3 and is also related to Acknowledgements
the ease with which these species are generated in reac-
Authors gratefully acknowledge the VGST, Govt. of
Karnataka, India for the CESEM award grant No. 24
(2010-11). We are also thankful to Prof. M.A. Pasha and
the anonymous reviewer for their valuable suggestions.
tions. In these oxidation reactions, the electronegativity
values of Br+ and Cl+ play a vital role. Bromine has
the electronegativity of 2.7, whereas for chlorine it is
2.8. As the electronegativity increases, the electroposi-
tive nature decreases. Further, this trend is also due to
more value of K3 for BAT (1.08 × 103M−1) in compar- References
ison with that of CAT (0.96 × 103 M−1). Therefore, the
1. Sweetman S C 2002 In Martindale: The Complete Drug
reactivity of BAT is more when compared with CAT.
This trend may also be due to the moderate difference
in the van der Waals radii of bromine and chlorine. A
similar behaviour has been noted in the oxidation of
several other substrates with CAT and BAT.34–37 The
facts furnished in this research and the literature reports
led us to conclude that BAT is a stronger oxidant than
CAT.
Reference 33rd edn. (U K: Pharmaceutical Press)
2. Muijsers R B R and Goa K L 2002 Drugs 62 1689
3. Hussain R N, Ajjan R A and Riley S A 2000 British. J.
Clin. Pharmacol. 4 323
4. Ananda kumar K,Varadharajan K, Ayyappan T,
Nageswara Rao P and Sujatha K 2008 Research J.
Pharm. Tech. 1 472
5. Kaja R K, Surendranath K V, Radhakrishanand P, Satish
J and Satyanarayana P V V 2009 Chromatographia 69
1007
6. Mandhanya M, Nithin Dubye, Nidhi Dubey, Sharma
P S and Hardenia 2011 Asian. J. Pharma. Med. Sci. 1 13
7. Campbell M M and Johnson G 1978 Chem. Rev.78 65
8. Bremner D H 1986 Synth. Reagents 6 9
9. Banerji K K, Jayaram B and Mahadevappa D S 1987 J.
Sci. Ind. Res. 46 65
10. Agarwal M C and Upadhyay S K 1990 J. Sci. Ind. Res.
49 13
11. Armesto X L, Canle L, Garia M V and Santaballa J A
1998 Chem. Soc. Rev. 27 453
12. Geethanjali A 2005 Synlet 18 2857
3.11 Activation parameters
The proposed mechanism is also supported by the mod-
erate values of energy of activation and other thermody-
namic parameters (table 3). The energy of activation is
the highest for the slowest reaction and vice-versa, indi-
cating that the reaction is enthalpy controlled. The neg-
ative values of ꢀS# indicate a greater degree of order-
ing in the transition state than in the initial state, due to 13. Kolaveri E and Ghorbeni-Choghamarani A 2007 J. Iran
Chem. Soc. 2 126
an increase in solvation during the activation process.
Further, the closeness values of ꢀG# signify that the
same type of reaction mechanism could be operative for
the oxidation of BSZ with both CAT and BAT in acid
medium. The values of frequency factor (A) specify the
frequency of collisions and the orientation of reacting
molecules.
14. Jagadeesh R V and Puttaswamy 2013 In Encyclopedia of
Reagents for organic synthesis. Chloramine-T: Second
update. RC056 9
15. Nair C G R, Kumari R L and Indrasenan P 1978 Talanta
27 525
16. Puttaswamy, Jagadeesh R V and Gowda N M M 2005
Int. J. Chem. Kinet. 37 700
17. Obeid A A 2009 Rasay. Jour. 2 786
18. Puttaswamy and Shubha J P 2009 AIChE Jour. 55 3234
19. Anu Sukhdev and Puttaswamy 2012 Bull. Korean Chem.
Soc. 33 3544
20. Morris J C, Salazar J A and Wineman M A 1948 J. Am.
Chem. Soc. 70 2036
4. Conclusions
The kinetics of oxidation of BSZ with CAT and
BAT in acidic (HClO4) medium follows the iden-
tical kinetics with a rate law –d[oxidant]/dt = k
[BSZ] [oxidant]x [H+]y, where x and y are less
than unity. 2-hydroxy-5-nitroso-benzoic acid and 3-(4-
nitroso-benzoylamino)-propionic acid are identified as
the oxidation products of BSZ. Thermodynamic param-
eters and reaction constants were deduced. In the pro-
posed mechanism, TsNHX is assumed to be the reac-
tive species, which interacts with the substrate. The
relevant rate law has been deduced. Under identical
set of experimental conditions, the rate of oxidation
of BSZ is about five-fold faster with BAT than with
CAT.
21. Akerloff G 1932 J. Chem. Soc. 54 4125
22. Bishop E and Jennings V J 1958 Talanta 1 197
23. Murthy A R V and Rao B S 1952 Proc. Ind. Acad. Sci.
35 69
24. Pryde B G and Soper F G 1962 J. Chem. Soc. 1582
25. Hardy F F and Johnston J P 1973 J. Chem. Soc. Perkin
Trans II 742
26. Sari N and Gurkan P 2004 Z. Naturforsch 59b 692
27. Moelwyn-Hughes E A 1961 In Physical Chemistry 2nd
edn. (New York: Pergamon)
28. Bensen S W 1960 In The foundation of Chemical Kinet-
ics (New York: McGraw-Hill)
29. Frost A A and Pearson R G 1961 In Kinetics and
Mechanism 2nd edn. (New York: Wiley)
30. Laidler K J 1963 In Reaction Kinetics (New York:
Pergamon)