Etude de la réactivité du fluorure de potassium sur des esters polyhalogénés

Reactions of polyhalogenated esters with potassium fluoride in polar solvents have been studied. Two kinds of reactions are possible depending on the starting compound: the hydrochlorinated estersRCCl₂CH₂CHR′CO₂CH₃ (R=Cl, -CF₃ ; R′=H, -CH₃ give the corresponding α-β unsaturated derivatives. Moreover when using ethylene glycol as a solvent, a transesterification reaction occurs after the dehydrohalogenation. From perhalogenated esters, mainly decarboxylation products are formed; for example in DMSO as a solvent, the fluorination of the telomers Cl-(CFClCF₂)_n-CO₂CH₃ yields the corresponding perfluoroalkenes C_2nF_4n. Some mechanistic interpretations are given in order to explain the formation of the different compounds.