Acyl fluorides
Acyl fluorides are organofluorine compounds with the formula RCF. In terms of structure, they resemble the more common acyl chlorides, i.e., an acyl group bonded to a halide. The synthesis and properties of acyl fluorides are somewhat distinctive however.
Preparation
The several routes to acyl fluorides can be roughly subdivided into three approaches.Halide exchange
react with hydrogen fluoride to give acyl fluorides. This reaction is relevant to the use of electrofluorination route to perfluorinated carboxylic acids, such as PFOA.S- and P-based reagents
The OH group of carboxylic acids can be converted to fluoride using various oxophilic reagents. Aromatic acyl fluorides can be prepared from carboxylic acids with and fluoride sources. Cyanuric fluoride as well as sulfur tetrafluoride also convert carboxylic acids to acyl fluorides.Fluorophosgene
Salts of trifluoromethoxide react with carboxylic acids to give acyl fluorides. The process entails formation of difluorophosgene. Solutions of trifluoromethoxide are prepared by displacement from aryl trifluoromethyl ethers.Reactions
A common reaction of acyl fluorides is hydrolysis to the carboxylic acid.Perfluoroacyl fluorides react with fluoride salts to perfluoroalkoxides: