Jp. Lorimer et al., INVESTIGATION OF THE CONSUMPTION OF DIPHENYLPICRYLHYDRAZYL IN SOLUTION IN THE ABSENCE AND PRESENCE OF ULTRASOUND, Journal of the Chemical Society. Faraday transactions, 91(7), 1995, pp. 1067-1074
Citations number
21
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The reaction by which diphenylpicrylhydrazyl (DPPH) is decolorised in
trichlorobenzene, toluene and benzene solution in the absence of ultra
sound and at elevated temperatures has been demonstrated to conform to
first-order kinetics. This reaction is best rationalised as resulting
from an abstraction reaction between DPPH and the solvent. The activa
tion energy for this reaction is in good agreement with those deduced
for the abstraction reactions between a polystyrene macro-radical and
either toluene or benzene. The reaction of DPPH in the presence of ult
rasound has also been shown to occur by an abstraction reaction and no
t by reaction with radicals resulting from the extremes of temperature
and pressure generated as the cavitation bubbles collapse. The rate c
onstants for this reaction, determined over a wide range of sonochemic
al conditions, appear to be dependent on the power dissipated by the u
ltrasonic horn, the diameter of the irradiating horn and the vapour pr
essure of the solvent.