“On-water” catalysis, the unusual activity of water molecules at the organic solvent–water interface, has been demonstrated in many organic reactions. However, the catalytic mechanism has remained unclear, largely because of the irreproducibility of the organic–water interface under the common stirring condition. Here, the interfacial area was controlled by employing adsorbed water on mesoporous silica nanoparticles as the catalyst. Reliable kinetics of the cycloaddition reaction of quadricyclane and diethyl azodicarboxylate (DEAD) at the toluene–water interface within the nanoparticle pores were measured. Data reveal an Eley–Rideal mechanism, wherein DEAD adsorbs at the toluene–water interface via hydrogen bonds formed with interfacial water, which lower the activation energy of the cycloaddition reaction. The mechanistic insights gained and preparation of surface water in silica pores described herein may facilitate the future design of improved “on-water” catalysts.
Bibliographical noteKAUST Repository Item: Exported on 2021-03-22
Acknowledgements: We thank Dr. Ziliang Mao for the fruitful discussion. This work was supported by the UC Office of the President within the Multicampus Research Programs and Initiatives (M21PL3263) (S.C.N., R.J.S.), Director, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy under Contract No. DEAC02-05CH11231 through the Chemical Sciences Division of the Lawrence Berkeley National Laboratory (R.J.S., H.M.), the King Abdullah University of Science and Technology (E.R.), and the University of California’s Leadership Excellence through
Advanced Degrees program (A.G.).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- General Materials Science