M. M. Boudakian
Oct 1, 1981
Citations
0
Influential Citations
16
Citations
Journal
Journal of Fluorine Chemistry
Abstract
Abstract The isolation and stabilization of elusive 4-fluoropyridine as the hydrochloride salt (54% yield) from fluorodediazoniation of 4-aminopyridine in anhydrous hydrogen fluoride (AHF) is described. Unlike the low yields (0–13%) recently reported from the chlorodediazoniation of 2,6-diaminopyridine and 3-halo-2,6-diaminopyridine, fluorodediazoniation gave high yields (49–62%) of the corresponding 2,6-difluoropyridines. In contrast, benzene analogs, i.e. m -phenylenediamine and 4-chloro- m -phenylenediamine, form only tars under similar fluorination conditions. Vicinal aminohalopyridines, e.g. 3-amino-2-chloropyridine and 2-amino-3,5-dichloropyridine give the corresponding fluorohalopyridine in 49–89% yield. Again, the benzene analogs, i.e. o -chloroaniline and 2,4-dichloroaniline, resist fluorination.