An Experimental Study on Direct Hydroxylation of Toluene in a Dielectric Barrier Discharge System Under Ambient Conditions

Non-thermal plasma is a promising alternative to be utilized for the synthesis of hydroxytoluenes through one-pot hydroxylation of toluene. Direct preparation of hydroxytoluenes from vaporized toluene was conducted in air at room temperature and atmospheric pressure using a dielectric-barrier discharge (DBD) reactor. The preliminary results obtained from this study showed that cresols were formed along with benzaldehyde, benzyl alcohol, and phenol. O atoms generated by air plasma in collision with toluene produced OH and benzyl radicals, which led to further reactions. The mechanism of the reaction of reactive oxygen species (ROS) with toluene and toluene-derived radicals to yield the observed oxidation products was discussed.