Perfluoroalkylsulfonylimide Zwtterions-induced Recovery Of Used Acid Catalyst

The emissions of acidic substances on industrial lead to serious environmental roblems such as soil and water contamination, Along with environmental protection oice rising, the research of rational design of acid become focus. We desighed a strategy recycle the widely used liquid acid catalysts in industry.To demonstrate the feasibility of this strategy, four perfluorobutyl ulfonylimide-containing imidazolium-based zwitterions was synthesized. Their tructrues were confirmed by FT-IR, 1H NMR,13C NMR,19F NMR, MS technology.Having the expected zwitterion in hand, we then tried to use it to recover triflic acid rom nitromethane. Recycling mechanism as follows:The optimal condition is:zwitterion:CF3SO3H=2:1, strring at 40℃ for 1 h in ound glask, After three times of extractions,90% of triflic acid could be recovered, witterion was also achieved a nice recovery ratio(> 91%). Compare the acid recycling bility of different zwitterions, found that imidazole- zwitterions is better than pyridine ype.To explore the effect Factors of acid recovery, the zwitterions reacted with several cids to form ILs. Then measured their acid strength using Hammett and Guttaman nethod. Results revealed that:(1) The acidity of ILs synthesized in this topic weaker han their corresponding liquid acids, H+ shifted from O to N, ILs were formed; (2) The cidity of ILs synthesized in this topic stronger than the ILs [(HO3S)C3C1im][OTf], (HO3S)C3pyr][OTf], which have been used as recyclable catalysts. Therefore, the ormed ILs in this topic were unstable. In general, zwitterions designed in this topic all ad the ability of recovery acids. Acid strength affect recovery effect.The Micheal addtion and rupe rearrangement reaction were selected as model eaction to examine the application value of the acid recycle strategy. The recovery of CF3SO3H reached 90%, and triflic acid catalyst could be recycled at least two times without significant mass and catalytic activity losses.