Comparison of the reactions of organic bromides and p-toluene sulphonates with polymeric anions

Abstract

Alkyl bromides and tosylates were shown to react quantitatively with the living α-methylstyrene tetramer to yield the dialkyl adduct. Alkyl bromides also reacted with α-methylstyrene and lithium in THF to yield the dimeric adduct quantitatively, whereas only about 10% yield of this product was obtained with alkyl tosylate. This difference in behaviour was interpreted in terms of the different adsorptive powers of the two alkyl salts onto lithium metal. Aryl (phenyl) bromides and tosylates reacted with the tetramer to give only low (<5%) yields of the diaryl adduct and in both cases low molecular weight poly(α-methylstyrene) was produced. Benzene was also formed with phenyl bromide and the reaction was explained in terms of a transmetallation process. With the tosylate, the presence of phenol indicated that scission occurred at the SO 2Obond. The reactions of these reagents with α-methylstyrene and lithium in THF both yielded poly(α-methylstyrene) and phenyl bromide was quantitatively converted into biphenyl. Reactions controlled by competitive adsorption were invoked to explain these findings.