On the dichotomy of the S_N2/ET reaction pathways: an apparent S_N2 reactivity in the reaction of naphthalene dianion with alkyl fluorides

摘要

Dilithium naphthalene (Li_2C_(10)H_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 more to secondary and tertiary alkyl fluorides. Significantly, lithium naphthalene (LiC_(10)H_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.