Nucleophilic displacement in polyhalogenoaromatic compounds. Part 8. Kinetics of methoxydefluorination of some polyfluoronaphthalenes

Abstract

The kinetics of methoxydefluorination of some 2-X-heptafluoronaphthalenes (X = H, F, Cl, OMe, or C₆H₅) and of 1,2,3,4,5,6-hexafluoronaphthalene in methanol at 323.2 K have been measured. The orientation of attack has been confirmed in the naphthalene derivatives as mainly involving displacement at C-6, although some evidence has been found for attack at C-7 in 2-methoxyheptafluoronaphthalene. Similar studies have been made of the orientation of methoxydefluorination of 2,3,4,5,6-penta- and of octa-fluorotoluene, together with a study of the rate of reaction of the latter compound. The rate constants are explained in terms of a transmission of the total substituent effect of the groups across the biannular system.