ChemInform Abstract: Cleavage of Perfluorinated Tertiary Amines with Antimony(V) Fluoride.

Abstract

Cleavage reactions of perfluorinated tertiary amines in the presence of antimony pentafluoride are studied in detail.

The Chemistry of Highly Fluorinated Carbocations

“…The mechanism of the isomerization is similar to that proposed for the isomerization of cyclic tertiary perfluoroamines by SbF 5 (see section IV.F.7.c) and involves formation of immonium cation 191 as a result of abstraction by SbF 5 of fluoride from the CF 2 group, then ring opening leading to formation of final product through carbocation 192 .

…”

“…As a result, a number of reactions with strong electrophiles are known for fluorinated amines. Examples of reactions with strong Lewis acids have now been found for practically all groups of polyfluoroamines, including CF 3 ONF 2 , SF 5 NF 2 , CINF 2 , R f NF 2 , (R f ) 2 NF, and (R f ) 3 N. − All have basically the same mechanism involving coordination of Lewis acid at fluorine to form a positively charged nitrogen species, then decomposition of the intermediate into perfluoroalkane and either a stable nitrogen-containing transient species (for example, :N−F) or an imine. In the case of perfluoroamines containing the −NF 2 group, reaction starts with ionization or polarization of a weak N−F bond.…”

“…Reasonable rates of reaction can be achieved at 120−130 °C to give a mixture of perfluoroalkane and imidoyl fluoride 247 . Perfluoro- N -alkylpiperidines with SbF 5 eliminate the N-alkyl group to form cyclic imine (eq 198) …”

Synthesis of trifluoromethylated heterocycles using partially fluorinated epoxides

“…CsF (Aldrich) was dried at 100-120 8C under dynamic vacuum for 4-8 h and was stored and handled inside of the dry box. C 4 F 9 N5 5CFC 3 F 7 was prepared using literature procedure [36]. Due to a high ratio of sulfur to fluorine, elemental analysis was not attempted for new materials prepared in this study.…”

“…Perfluorinated isothiocyanates 25 [29][30][31] and 26 [32] readily prepared by the reaction of perfluoro(2-methyl)pentene-2 [33,34] or perfluoro-4-aza-nonene-3 [35,36] with sodium thiocyanate were used for the synthesis of a variety of fluorinated heterocycles (see Refs. [37][38][39][40][41][42][43][44][45][46][47][48] and [32] for reactions of 25 for 26, respectively).…”