Oxidation reactions that exhibit potential energy values consistent with experimental results are Q2, Q7, and Q9. Each reaction evolves from a different thermodynamic species; i.e., i) [Al(EtOH) 6 ] 3+ + QH 2 , ii) [Al(EtOH) 5 (EtO -)] 2+ + QH 2 , and iii) [Al(EtOH) 5 (QH -)] 2+ , respectively. Oxidation reactions with higher negative oxidation potentials than Q2, Q7, and Q9 reactions entail more endergonic processes than these where unstable species are formed and, consequently, they can be automatically discarded as possible hydroquinone's oxidation reactions in solution with the presence of Al 3+ . Q4 and Q10 reactions deserve further comments because entail exergonic and spontaneous processes that should be preferred over endergonic ones. However, further remarks can be made taking into account the experimental conditions.