Glass Surface as Strong Base, ‘Green’ Heterogeneous Catalyst and Degradation Reagent

Abstract

Systematic screening of accelerated chemical reactions at solid/solution interfaces has been carried out in high-throughput fashion using desorption electrospray ionization mass spectrometry and it provides evidence that glass surfaces accelerate various base-catalyzed chemical reactions. The reaction types include elimination, solvolysis, condensation and oxidation, whether or not the substrates are pre-charged. In a detailed mechanistic study, we provide evidence using nanoESI showing that glass surfaces can act as strong bases and convert protic solvents into their conjugate bases which then act as bases/nucleophiles when participating in chemical reactions. In aprotic solvents such as acetonitrile, glass surfaces act as ‘green’ heterogeneous catalysts that can be recovered and reused after simple rinsing. Besides their use in organic reaction catalysis, glass surfaces are also found to act as degradation reagents for phospholipids with increasing extents of degradation occuring at low concentrations. This finding suggests that the storage of base/nucleophile-labile compounds or lipids in glass containers should be avoided. <br>

Water–solid contact electrification causes hydrogen peroxide production from hydroxyl radical recombination in sprayed microdroplets

“…Typically, Si- 18 O - ions can work as a base to accelerate some reactions by promoting the stoichiometric deprotonation step ( 33 , 34 ). Si- 18 O - ions could react with H 2 O + to form hydroxyl radicals during the contact electrification process: …”

“…The results of this study may therefore help us understand the mechanism of H 2 O 2 generation in the environment and explain how nature behaves, such as the seasonality of viral respiratory infections ( 38 ). In addition, we have considered a recent report ( 34 ) that glass surfaces can act as heterogeneous catalysts to accelerate various base-catalyzed reactions. The present study may help us further understand the heterogeneous catalytic reaction at the solid–water interface and design interfacial catalysts to replace homogeneous catalysts that need to be dispersed in the bulk phase.…”