New research results show that glass can accelerate various base-catalyzed reactions and the breakdown of base-labile biomolecules. The work is intended to remind chemists to carefully choose the containers in which to store chemicals and carry out reactions.
Last year, Yangjie Li and colleagues in the Graham Cooks laboratory at Purdue University, USA, reported how glass surfaces can accelerate the Katritzky transamination reaction. I doubted they were lucky enough to “discover the only reaction that glass can accelerate, and thought we should maybe try all the major organic reactions,” Li explains.
The group has now used a high throughput system to screen the rates of various reactions in the presence and absence of glass microspheres. To their surprise, they found that all base-catalyzed reactions, including elimination, solvolysis, condensation, and oxidation reactions, were accelerated by glass. They attribute this to strongly basic silanolate groups on the glass surface, which can take part directly or indirectly in the reaction by converting protic solvents into their conjugate bases. The acceleration effects were greater at lower concentrations because a greater proportion of the material was on the glass surface.
They also found that glass accelerates the breakdown of phospholipids. Yu Xia, a bioanalytical chemist at Tsinghua University in China, says the lipidomist community should be aware of this as lipids are often stored in glass containers to avoid contamination from plastic. “This new finding clearly leads to caution when using methanol or other protic organic solvents for lipid storage in glass containers, as this effect can lead to both incorrect identification and inaccurate quantification in lipid analysis.”
Cooks hopes the work will stimulate chemists to think carefully about the containers in which to store chemicals and perform reactions, “especially when working at very low concentrations, which is increasingly the case as this is where these effects come into play.”
While they might alarm organic and analytical chemists, the results also underscore the potential of glass as a green heterogeneous catalyst. “You can just rinse it out and all of the catalytic power will be recovered,” says Li. “It’s a great way to avoid corrosive chemicals.” Li and colleagues achieved reaction rates up to 1000 times faster with glass. Since the acceleration depends on the glass surface, there is the potential to increase these uniform values even further.