Researchers at Tu Berlin’s UnisyScat Cluster of Excellence synthesized a silicon-based Super Lewis acid containing additional halogen atoms for the first time.
These compounds rank among the most powerful Lewis acids known to date and are capable of attacking very stable chemical bonds, such as the carbon fluorophore bonds of PFA.
New compounds are not consumed during the reaction and can be regenerated instead. Therefore, they act catalytically and present critical advantages for potential applications in recycling processes and green chemistry.
Why is it so difficult for PFAS bonds to break down?
The extreme difficulty of decomposeting PFAS bonds results in a single, incredibly strong chemical bond, namely, a bond of carbon fluorophore (CF). This bond is one of the most powerful organic chemistry due to the high electronegativity of fluorine, allowing for the creation of very stable short covalent bonds with carbon.
This unique chemical stability requires a considerable amount of energy to break it. Traditional chemical and biological degradation processes that can degrade many other organic compounds are simply not strong enough.
This is why PFA is known as an “eternal chemical.” This is because it has been in the environment for decades, leading to extensive contamination of soil and water. The strength of CF bonds is a key issue for scientists developing new repair technologies.
Electronic Hunger allows for PFA degradation
The stability of PFAs is particularly due to strong carbon bonds, and to break them, substances with very high affinity for electron pairs are required.
The newly developed Super Lewis acid meets this requirement. The combination of silicon and halogen atoms produces extreme electron deficiency, allowing the decomposition of PFAS bonds.
The synthesis process is complicated because the material must be treated under inert conditions to prevent contamination. Neither oxygen nor water will encounter any compounds.
Breakthrough was achieved using manufacturing decomposition, which was previously applied to carbon chemistry and is now adapted for use in silicon chemistry.
Lewis acid regeneration provides predictive power
In addition to experimental work, theoretical calculations played an important role. Quantum chemistry allows researchers to predict purely the acidity of molecules from their structure, and these predictions were later verified experimentally using NMR spectroscopy.
According to the team, the new Super Lewis acids are extremely promising in tackling PFA contamination in both environmental and industrial contexts.
Because they are regenerating, even small amounts of acids can be sufficient to neutralize large amounts of these persistent contaminants.
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