Terephthalic,
isophthalic and phthalic acids (4a,b,c) were obtained in moderate yields from p-, m- and o-xylene
respectively (table 4). The oxidation of xylenes is probably a stepwise process. Around 20% of toluic
acids (methylbenzoic) were also obtained. To our surprise, small amount of benzoic acid was also
detected. Using a less powerful 300W reactor, similar results were obtained except the reaction time
required was 2 hours