A unique ultrasonic online spectrophotometric system for kinetic measurements of homogeneous polar reactions under ultrasound was developed. The setup consists of an ultrasonic bath, an HPLC UV/Vis detector, an HPLC pump, a refrigerated heating circulator bath, and a data processing unit. An analogue–digital converter was constructed and a data processing program AD_com was written for registration of detector signal. The pH-independent hydrolysis of 4-nitrophenyl chloroacetate as a model reaction and also sonolytic degradation of 4-nitrophenol were used for the examination of the online spectrophotometric system. Preliminary kinetic studies proved that the system can be successfully applied for ultrasonic kinetic investigations of polar homogeneous reactions. This online system allows a sensitive and reproducible monitoring of various homogeneous processes, which can be detected spectrophotometrically under ultrasonic irradiation.
1. Mason, T. J. Practical Sonochemistry: User's Guide to Applications in Chemistry and Chemical Engineering. Ellis Horwood Limited, Chichester, 1991.
2. Mason, T. J. (ed.) Sonochemistry: The Uses of Ultrasound in Chemistry. The Royal Society of Chemistry, Cambridge, 1990.
3. Cravotto, G. and Cintas, P. Power ultrasound in organic synthesis: moving cavitational chemistry from academia to innovative and large-scale applications. Chem. Soc. Rev., 2006, 35(2), 180–196.
http://dx.doi.org/10.1039/b503848k
4. Luche, J. L. Synthetic Organic Sonochemistry. Plenum Press, New York, 1998.
5. Tuulmets, A., Cravotto, G., Salmar, S., and Järv, J. Sonochemistry of homogeneous ionic reactions. Mini-Rev. Org. Chem., 2010, 7(3), 204–211.
http://dx.doi.org/10.2174/157019310791384155
6. Tuulmets, A., Salmar, S., and Järv, J. Sonochemistry in Water Organic Solutions. Nova Science Publishers, New York, 2010.
7. Salmar, S., Cravotto, G., Tuulmets, A., and Hagu, H. Effect of ultrasound on the base-catalyzed hydrolysis of 4-nitrophenyl acetate in aqueous ethanol. J. Phys. Chem. B, 2006, 110, 5817–5821.
http://dx.doi.org/10.1021/jp057405w
8. Hagu, H., Salmar, S., and Tuulmets, A. Impact of ultrasound on hydrophobic interactions in solutions: ultrasonic retardation of benzoin condensation. Ultrason. Sonochem., 2007, 14(4), 445–449.
http://dx.doi.org/10.1016/j.ultsonch.2006.09.012
9. Tuulmets, A., Järv, J., Salmar, S., and Cravotto, G. Ultrasonic detection of hydrophobic interactions: a quantitative approach. J. Phys. Org. Chem., 2008, 21, 1002–1006.
http://dx.doi.org/10.1002/poc.1415
10. Tuulmets, A., Järv, J., Tenno, T., and Salmar, S. Significance of hydrophobic interactions in water-organic binary solvents. J. Mol. Liq., 2009, 148, 94–98.
http://dx.doi.org/10.1016/j.molliq.2009.06.008
11. Petrier, C. and Casadonte, D. The sonochemical degradation of aromatic and chloroaromatic contaminants. Adv. Sonochem., 2001, 6, 91–109.
12. Abedini, R. and Mousavi, S. M. Preparation and enhancing of materials using ultrasound technique: polymers, catalysts and nanostructure particles. Petroleum Coal, 2010, 52(2), 81–98.
13. Cornpton, R. G., Eklund, J. C., and Marken, F. Sonoelectrochemical processes: a review. Electroanalysis, 1997, 9(7), 509–522.
http://dx.doi.org/10.1002/elan.1140090702
14. Mason, T. J., Lorimer, J. P., and Mistry, B. P. The effect of ultrasound on the solvolysis of 2-chloro-2-methylpropane in aqueous ethanol. Tetrahedron, 1985, 41, 5201–5204.
http://dx.doi.org/10.1016/S0040-4020(01)96767-5
15. Mark, G., Tauber, A., Laupert, R., Schuchmann, H.-P., Schulz, D., Mues, A., and von Sonntag, C. OH-radical formation by ultrasound in aqueous solution. Part II: Terephthalate and Fricke dosimetry and the influence of various conditions on the sonolytic yield. Ultrason. Sonochem., 1998, 5(2), 41–52.
http://dx.doi.org/10.1016/S1350-4177(98)00012-1
16. Jiang, Y., Petrier, C., and Waite, T. D. Sonolysis of 4-chlorophenol in aqueous solution: effects of substrate concentration, aqueous temperature and ultrasonic frequency. Ultrason. Sonochem., 2006, 13(5), 415–422.
http://dx.doi.org/10.1016/j.ultsonch.2005.07.003
17. Piiskop, S., Hagu, H., Järv, J., Salmar, S., and Tuulmets, A. Sonication effects on ester hydrolysis in alcohol–water mixtures. Proc. Estonian. Acad. Sci. Chem., 2007, 56, 199–206.
18. Cravotto, G. and Cintas, P. The combined use of microwaves and ultrasound: improved tools in process chemistry and organic synthesis. Chem. Europ. J., 2007, 13(7), 1902–1909.
http://dx.doi.org/10.1002/chem.200601845
http://dx.doi.org/10.1021/es8013375
