Mechanism of polymerization reaction of 4-[(n-butylsulfinyl)methyl]-4′-(chloromethyl)benzene

The polymerization reaction of 4-[(n-butylsulfinyl)methyl]-4′-(chloromethyl)benzene (1a) with t-BuONa in CH₂Cl₂/monomethylformamide (MMF) (4/6) was studied kinetically. The reaction proceeds in two steps; the formation of a p-quinodimethane intermediate (M) followed by the polymerization of M. Results of kinetic studies and H-D exchange experiments reveal that the 1,6-elimination proceeds by the (E1cb)_irr mechanism. The rate of the disappearance of M was increased by the carbanion and S₂O₈^2-, inhibited by TEMPO and unaltered by the addition of HCl. From these results, a free radical polymerization mechanism is proposed.