The dehydrogenation of γ-terpinene was studied under catalyst- and solvent-free reaction conditions using air as an oxidant. The dehydrogenation affords p-cymene in good yields in a continuous flow reaction setup. The initial optimization of the reaction parameters showed that the dehydrogenation is highly dependent on the vapour/liquid phase equilibrium and the availability of oxygen in the vapour phase.
Asikainen, M., Jauhiainen, O., Aaltonen, O., & Harlin, A. (2013). Continuous catalyst-free aromatization of γ-terpinene using air as an oxidant. Green Chemistry, 15(11), 3230-3235. https://doi.org/10.1039/c3gc41224e