Acid-assisted water loss in perrhenate-catalysed deoxydehydration: an agent-assisted reaction-network search with microkinetic modelling

Perrhenate is the cheapest and most robust deoxydehydration (DODH) catalyst. Two decades of reports show that protic and acidic environments make it work, and no study has located where the proton acts. We answer that question by providing a predicted mechanism that is consistent with observed kinetics. The authors set the mechanistic hypotheses, and an AI agent located the corresponding transition states, which the authors then validated; solvent participation was resolved shell by shell, including its complex temperature dependence; and the free energy surface was converted into rates via microkinetic simulation on coupled-cluster-anchored energies. The predicted mechanism is proton-gated at its water-loss steps: a proton converts Re-OH into water, which leaves, thereby unlocking both the diol ring closure and alcohol reduction steps. This yields an increase in the predicted rate by eight orders of magnitude over the best proton-free chemistry we could locate. Compared like-for-like with the batch experiments, the model falls within the 31.5-34.0 kcal mol^-1 window derived from reported turnover.