Aerosol direct fluorination : syntheses of perfluoroketones

A series of perfluoroketones has been synthesized utilizing the aerosol direct fluorination method. The perfluoroketones are obtained directly from the hydrocarbon analog in the case of acyclic ketones, and in a two-step process from the corresponding methyl ether or ethylene glycol ketal in the case of cyclic ketones. Aerosol direct fluorination of the hydrocarbon analog produced the following perfluoroketones directly: F-3-pentanone, F-2-heptanone, F-3-heptanone, F-4-heptanone, F-2-butanone, F-acetone, and F-3,3-dimethyl-2- butanone. Aerosol direct fluorination of 2,2,4,4-tetramethyl-3-pentanone produced £-2,2,5-trimethyl-3-hexanone, a rare example of a skeletal rearrangement occuring during aerosol fluorination. Aerosol direct fluorination of methoxycyclopentane and methoxycyclohexane produced the perfluorinated analogs, which were then hydrolyzed in 100% sulfuric acid to F-cyclopentanone and F-cyclohexanone, respectively. Aerosol direct fluorination of the ethylene glycol ketals of cyclopentanone and cyclohexanone produced the perfluorinated analogs, which could also be hydrolyzed in 100% sulfuric acid to F-cyclopentanone and F-cyclohexanone, respectively, the first example of the use of a protecting group in direct fluorination. The perfluoroketones were characterized by infrared spectrophotometry, electron-impact and chemical ionization mass spectroscopy, and ¹⁹F nuclear magnetic resonance spectroscopy.

In the course of the syntheses the basic aerosol fluorination system was modified to produce a more versatile system. The modifications have made possible the aerosol direct fluorination of both solid and high boiling liquid hydrocarbon materials on a routine basis.