Direct oxidation of the three xylene isomers (3) with 5 folds excess of 70% aqueous TBHP (each
oxidation requires 6 equivalents of oxidant) under simultaneous cooling were carried out in a 800W
microwave reactor. Results after 30 minutes irradiation are summarized in table 4. 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.