Sb. Sharma et al., RADIATION-CHEMICAL OXIDATION OF BENZALDEHYDE, ACETOPHENONE, AND BENZOPHENONE, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 101(45), 1997, pp. 8402-8408
Radiation chemical reactions of (OH)-O-., O.-, and SO4.- with benzalde
hyde, acetophenone, and benzophenone have been studied using both puls
e and steady-state radiolysis techniques. The observed rates for the (
OH)-O-. addition (k = (2.6-8.8) x 10(9) M-1 s(-1)) are higher than tho
se found for the SO4.- reaction (k = (0.7-4.0) x 10(9) M-1 s(-1)). The
rate for the reaction of O.- with benzaldehyde is higher than that fo
und for (OH)-O-., while a reverse trend is observed in the case of the
two ketones. Optical absorption spectra of the intermediate transient
s formed in the reactions of (OH)-O-. and SO4.- with all three compoun
ds are similar with a peak around 370-380 nm. The absorption spectra f
rom the O.- reaction have shown a major peak at 310 nm and are somewha
t different from those obtained in the reaction of (OH)-O-.. The yield
s of the phenolic products formed in the reaction of (OH)-O-. with ben
zaldehyde and acetophenone in the presence of 0.1 mM ferricyanide corr
esponded to only 30% and 50% (OH)-O-. yields, respectively. Benzoic ac
id is a major product formed with benzaldehyde in the reaction of (OH)
-O-. as well as SO4.- with G values of 2.1 and 1.3 per 100 eV, respect
ively. The formation of the exocyclic OH adduct is a major pathway in
the reactions of (OH)-O-. (by addition) and of SO4.- from hydrolysis o
f the initially formed radical cation (k = 2.4 x 10(4) s(-1)) with ben
zaldehyde. The exocyclic OH adduct undergoes disproportionation to giv
e benzoic acid. The formation of the exocyclic OH adduct of acetopheno
ne is possibly hindered owing to the bulky -COCH3 group.