Radical-anions nucleophilic behaviour

In order to measure the absorption spectra, the radical anions were generated electrochemically in the optical path of a spectrophotometer. The absorption spectrum of 3,5-dinitroanisole radical anion (Figure 11, curve c) is very similar to that of the 550-570 nm species produced photochemically. So we believe this species to be the radical anion formed by electron transfer from the nucleophile to the excited 3,5-dinitroanisole and decaying by interaction with its surroundings including the nucleophile radical cation. The behaviour described seems to be rather general for aromatic nitro-compounds since it is observed with a series of these compounds with various nucleophilic reagents. 

Mesitylfhjorenyl anion (9MsF ) is unreactive towards Mel at temperatures below —78 °C.100 Above —60 °C the absorption spectrum of 9MsF in the presence of Mel is replaced by that of the corresponding 9-mesitylfluorenyl radical (9MsF), and 9-methyl-9-mesitylfluorene is formed in low yield, hi a study of the electron-transfer photochemistry of chrysanthemol, an intramolecular S 2 reaction of a vinylcycloprop-ane radical cation has been observed.101 hi a long series of studies of the reactivity of the acids of trivalent phosphorus and their derivatives, the behaviour of P—O nucleophiles towards arylmethyl bromide systems has been examined.102 Further evidence for an X-philic substitution/SET tandem mechanism has been obtained. 

If, apart from the halide anion, other nucleophiles are present, the reaction may take a different course. For instance, in methanol the reaction shown in equation 28 took place. Initially formed l-bromo-2-methoxyhexene has rapidly reacted further to 52, which was hydrolysed to ketone 53. A similar behaviour was observed for bromine instead of chlorobromine ". With iodine in methanol a different product composition resulted terminal alkynes RC=CH (R = Bu, r-Bu and Ph) as well as 3-hexyne almost exclusively gave diiodoalkenes. The authors suggested that this addition of iodine follows a radical course. In the presence of silver nitrate, however, products expected for an ionic process were observed. 

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