Oxidation of substituted toluenes with molecular oxygen in the presence of N,N′,N-trihydroxyisocyanuric acid as a key catalyst

N,N',N-Trihydroxyisocianuric acid (THICA) was found to be a very efficient catalyst for the oxidation of alkylbenzenes with dioxygen. Thus, a variety of meta- and para-substituted toluenes bearing an electron-withdrawing substituent such as cyanotoluene, chlorotoluene, and toluic acid under O-2 (1 atm) in the presence of THICA (5 mol %) and Co(OAc)(2) (0.5 mol %) at 100 degreesC were smoothly oxidized to the corresponding benzoic acids in almost quantitative yields. The aerobic oxidation of toluene by THICA was compared with that by N-hydroxyphthalimide. p-Xylene was efficiently oxidized by THICA to telephthalic acid in high yield (over 95%) under mild conditions.