KINETICS OF HYDROLYSIS OF PROCAINE IN AQUEOUS AND MICELLAR MEDIA
9
surface or solubilized inside the hydrophobic interior,
and thereby decreases the rate of hydrolysis. The higher
inhibitive effect of DDTA may be due to better solu-
The project was supported by King Saud University, Dean-
ship of Scientific Research, College of Science Research
Centre.
+
bilization of the reactive ester group to the interior of
micelle by possessing the longer hydrophobic chain.
The lower inhibitive effect by TDTA micelles may
BIBLIOGRAPHY
+
1
2
. Burstein, C. L. Anesthesiology 1946, 7, 13.
. Foldes, F. F.; Hven, M. H. J Pharmacol Exp Ther 1952,
105, 259.
be attributed to its folding, resulting in weak binding
of procaine to the micellar surface.
−
The inhibition by DS micelles is the result of the
3. Raj, P. P.; Ohlweiler, D.; Hitt, B. A.; Denson, D. D.
Anesthesiology 1980, 53, 307.
preferential binding of procaine onto the micellar sur-
−
face/Stern region and expulsion of OH from the mi-
4
. Romsted, L. S. Micellization, Solubilization and Mi-
croemulsions, Mittal, K. L., Ed.; Plenum Press: New
York, 1982; Vol. 2.
cellar region. The reactive part of procaine molecules
binds to the hydrophobic hydrocarbon interior of the
−
micelles, whereas negatively charged OH ions are
5. Rosen, M. J. Surfactants and Interfacial Phenomena. 3rd
repelled by the negatively charged micellar surface.
ed.; Wiley-Interscience: Hoboken, NJ, 2004.
6. Khan, M. N. Micellar Catalysis, Surfactant Science Se-
ries, Vol. 133; CRC Press: Boca Raton, FL, 2007.
. Fendler, J. H.; Fendler, E. J. Catalysis in Micellar and
Macromolecular Systems; Academic Press: New York,
−
Thus, the micelles of DS keep the reactive center of
−
procaine and OH ions away from each other and slow
7
the rate of hydrolysis. The order of binding constant
(i.e., SDS > DDTAB > CTAB > TDTAB) for pro-
1975.
caine with micelles is not in the same order for the
rate of inhibition of the hydrolysis of procaine (i.e.,
SDS > CTAB > TDTAB > DDTAB). This may be
due to the micelles of the different surfactants hav-
ing different volume fractions in the micellar phase
8
. Al-Lohedan, H. A.; Bunton, C. A.; Mhala, M. M. J Am
Chem Soc 1982, 104, 6654.
. Al-Lohedan, H. A. J Chem Soc, Perkin Trans 1995, 2,
9
1
707.
0. Al-Lohedan, H. A. J Chem Soc, Perkin Trans 1990, 2,
401.
1
(at the same surfactant concentration). Among CTAB,
1
TDTAB, and DDTAB surfactants, the binding constant
is highest for DDTAB owing to its having a longer hy-
drocarbon chain; however, in TDTAB, the still longer
hydrocarbon chain may result in folding to have less
space for binding to procaine.
11. Broxton, T. J. Aust J Chem 1982, 35, 1357.
12. Al-Ayed, A. S.; Ali, M. S.; Al-Lohedan, H. A.; Al-
Sulaim, A. M.; Issa, Z. A. J Colloid Inter Sci 2011,
3
61, 205.
3. Menger, F. M.; Portnoy, C. E. J Am Chem Soc 1967, 89,
698.
1
4
1
1
4. Bunton, C. A. Catal Rev Sci Eng 1979, 20, 1.
5. Romsted, L. S. In Symposium on Surfactants in Solu-
tion, Lund: Sweden, 1982.
CONCLUSION
1
6. Al-Lohedan, H.; Bunton, C. A.; Romsted, L. S. J Phys
Chem 1981, 85, 2123.
The alkaline hydrolysis of procaine yields N,N-
diethylaminoethanol and p-aminobenzoate anion. The
rate of hydrolysis under the pseudo–first-order condi-
17. Higuchi, T.; Havinga, A.; Busse, L. W. J Am Pharm
Assoc, Sci Ed 1950, 39, 405.
−
tions ([OH ] ꢀ [procaine]) has been found to be lin-
18. Tomida, H.; Yotsuyanagi, T.; Ikeda, K. Chem Pharm
Bull 1978, 26, 148.
early dependent upon [NaOH]. The addition of cationic
1
2
9. Razvi, N.; Beg, A. E. J Chem Soc Pak 1981, 3, 121.
0. Reichardt, C. Solvents and Solvent Effects in Organic
Chemistry, 3rd ed.; Wiley-VCH: New York, 2003.
1. Rodenas, E.; Vera, S. J Phys Chem 1985, 89, 513.
2. Vera, S.; Rodenas, E. Tetrahedron 1986, 42, 143.
3. Cheong, May-Ye; Ariffin, A.; Khan, M. N. Bull Korean
Chem Soc 2007, 28, 1135.
(CTAB, TDTAB, and DDTAB) and anionic (SDS) sur-
factants to the reaction mixture (procaine and sodium
hydroxide) decreased the rate of hydrolysis. The max-
imum decrease in the rate constant was observed for
SDS micelles. Among the cationic surfactants, CTAB
inhibited the most. The orientation of reactive molecule
to the surfactant, values of the binding constant, and
volume fractions of micelles are attributed to the vari-
ation in the rate of hydrolysis of procaine in the micel-
lar media. The hydrolytic rate becomes negligible in
DDTAB micelles.
2
2
2
2
2
4. Hartley, G. S. Trans Faraday Soc 1934, 30, 444.
5. Meakin, B. J.; Winterborn, I. K.; Davies, D. J. G. J Pharm
Pharmacol 1971, 23, 25S.
26. Eriksson J. C.; Gilberg, G. Acta Chem Scan 1966, 20,
2019.
International Journal of Chemical Kinetics DOI 10.1002/kin.20735