Tailoring nanoscopic confines to maximize catalytic activity of hydronium ions

Hui Shi, Sebastian Eckstein, Aleksei Vjunov, Donald M. Camaioni, Johannes A. Lercher

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Acid catalysis by hydronium ions is ubiquitous in aqueous-phase organic reactions. Here we show that hydronium ion catalysis, exemplified by intramolecular dehydration of cyclohexanol, is markedly influenced by steric constraints, yielding turnover rates that increase by up to two orders of magnitude in tight confines relative to an aqueous solution of a Brønsted acid. The higher activities in zeolites BEA and FAU than in water are caused by more positive activation entropies that more than offset higher activation enthalpies. The higher activity in zeolite MFI with pores smaller than BEA and FAU is caused by a lower activation enthalpy in the tighter confines that more than offsets a less positive activation entropy. Molecularly sized pores significantly enhance the association between hydronium ions and alcohols in a steric environment resembling the constraints in pockets of enzymes stabilizing active sites.

Original languageEnglish
Article number15442
JournalNature Communications
Volume8
DOIs
StatePublished - 25 May 2017

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