ChemInform Abstract: Syntheses and Properties of N-Fluoropyridinium Salts.

Abstract

Various stable N-fluoropyridinium salts with a non- or weakly nucleophilic counter anion such as TfO−, FSO3−, BF4−, SbF6−, ClO4−, CH3SO3− etc., or with an electron-donating or -withdrawing substituent(s) on the pyridine ring were synthesized and their properties investigated. N-Fluoropyridinium-2-sulfonates, N-fluoroquinolinium triflate, and highly hindered N-fluoro-2,6-di-t-butylpyridinium salts were also synthesized. They were synthesized by counter anion displacement reactions of unstable pyridine-F2 compounds, fluorination of salts of pyridines with protonic acids or silyl esters with F2, and/ or fluorination of Lewis acid complexes of pyridines. The scope of each method was examined in detail. Each of the N-fluoropyridinium salts was assigned as the first stable 1 : 1 salt structure of the pyridine nucleus and halogen atom on the basis of the spectral and elemental analyses. The stability depended on the nucleophilicity or basicity of the counter anions and electronic nature or position of the ring s...