A-Methyl-p-methoxystyrene

Hydride transfer is especially favorable when it generates tertiary carbenium ions which are stabilized by phenyl, alkoxy, and/or vinyl groups. Degradation of poly(p-methoxystyrene) in the presence of acid indicates that hydride transfer occurs in p-methoxystyrene polymerizations [Eq. (98)] [29], Monomeric and oligomeric carbenium ions derived from a-methyl-p-methoxystyrene were detected by both NMR and UV, which indicates that hydride transfer at the chain end generates a tertiary carbenium ion which subsequently depropagates according to Eq. (98). 

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