Year: 2026
Type: preprint
Abstract: Selectivity between competing thermal reactions is, by textbook account, set either by the relative free energies of the products (thermodynamic control) or by those of the transition states leading to them (kinetic control). Neither principle applies to endergonic reactions: a non-equilibrium product concentration is maintained at the expense of an energy source, with species forming and decomposing simultaneously. Here we show that a third, distinct principle governs selectivity in endergonic reactions: the degree of turnover-frequency control, exerted by each intermediate of the kinetic barrier diagram associated to the reaction network. We demonstrate this principle experimentally, using a dynamic combinatorial system in which two furan derivatives compete for maleic acid in an endergonic Diels–Alder reaction driven by carbodiimide hydration. The product distribution depends on whether the system is at equilibrium or driven, and can be inverted under fueling. Kinetic measurements and analytical modeling quantitatively capture the observed selectivities – including counterintuitive non-monotonic responses – and recover thermodynamic and kinetic control as limiting cases.
Source: ChemRxiv
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221748062