On the dichotomy of the S N2/ET reaction pathways: an apparent S N2 reactivity in the reaction of naphthalene dianion with alkyl fluorides

Abstract

Dilithium naphthalene (Li 2C 10H 8) displays a S N2 reactivity profile in its reaction with alkyl fluorides ( n-, s- and t-octyl fluoride). S N2 seems to be the dominant mechanism operating with primary alkyl fluorides, which presumably turns into competition with ET as we move to secondary and tertiary alkyl fluorides. Significantly, lithium naphthalene (LiC 10H 8) seems to have also an important nucleophilic component when reacting with alkyl fluorides, in contrast to the previously proposed general ET process valid for all alkyl halides. These results explain the observed distribution of products and are reinforced by a complete analysis of the products originated by the reaction with 6-halohexenyl radical probes, whose main alkylation products are described here for the first time.