Surface activity of a series of fluoroether betaine amphoteric surfactants: Oxygen roles

As PFOS, PFOA and their derivatives were banned according to the Stockholm Convention for their potential bioaccumulation and toxicity, people attempted to substitute the legacy fluorosurfactants with short-chain ones. Although short-chain alternatives can alleviate bioaccumulation, surface activity was compromised. Fluorine industry kept seeking for effective solution. In this work, we prepared and investigated a series of fluoroether betaine surfactants for their surface activity and spreading property. The role of oxygen on surface activity was discussed. We found that insertion of oxygen atoms into fluorinated chain could increase hydrophobicity and thus enhance surface activity. The contribution of one oxygen is approximately half of that of a difluoromethylene group by experience. Moreover, introducing oxygen diversified the structure to fill in the gap of surface activity between short and long fluorosurfactants. In summary, this work provided basic knowledge for molecular design.

Deoxyfluorination of Carboxylic, Sulfonic, Phosphinic Acids and Phosphine Oxides by Perfluoroalkyl Ether Carboxylic Acids Featuring CF_(2)0 Units

The deoxyfluorination of carboxylic,sulfonic,phosphinic acids and phosphine oxides is a fundamentally important approach to access acyl fluorides,sulfonyl fluorides and phosphoric fluorides,thus the development of inexpensive,stable,easy-to-handle,versatile,and efficient deoxyfluorination reagents is highly desired.Herein,we report the use of potassium salts of perfluoroalkyl ether carboxylic acids(PFECA)featuring CF_(2)0 units as deoxyfluorination reagents,which are generated mainly as by-products in the manufacture of hexafluoropropene oxide(HFPO).The synthesis of acyl fluorides,sulfonyl fluorides and phosphoric fluorides can be realized via carbonic difluoride(COF_(2))generated in situ from thermal degradation of the PFECA salt.

Catalyst-Free Hydroxytrifluoromethylation of Alkenes UsingIodotrifluoromethane

The importance of CF3-containing molecules in pharmaceuticals, agrochemicals and materials intrigues the intense interest in synthetic methodology of these compounds. With a purpose to enrich trifluoromethylation methodology, we carefully examined the substrate scope of hydroxytrifluoromethylation of alkenes using iodotrifluoromethane, and the reaction provided β-trifluoromethyl alcohols in good yields under extremely mild conditions without catalysts. We found that our reaction can be applied to not only styrenes but also various aliphatic alkenes with excellent selectivity;no ketone was detected in most of our cases. Another feature of our discovery is “simple”. The reaction was carried out in air, irradiated by visible light, at room temperature and most importantly no catalyst was needed. A solution of CF3I in DMSO was used as the facile trifluoromethylating reagent, which simplified the utilization of gaseous CF3I. Based on 19F NMR spectroscopy, we observed a halogen bond between CF3I and tertiary amine in this reaction. The interaction may promote single electron transfer by the visible light irradiation.