Polymerization of α‐halogenated p‐xylenes with base

Abstract Various α‐halo‐ p ‐xylenes have been polymerized with base yielding p ‐xylylene polymers. The reaction involves a 1,6‐dehydrohalogenation to give a xylylene which then polymerizes. α,α′‐Dichloro‐ p ‐xylene forms poly‐α‐chloro‐ p ‐xylylene and polymers containing stilbene units; α,α,α′,α′‐tetrachloro‐ p ‐xylene gives poly‐α,α,α′‐trichloro‐ p ‐xylylene; alkyl, aryl, and halogen ring‐substituted α‐chloro‐ p ‐xylenes give the corresponding ring‐substituted poly‐ p ‐xylylenes. The more halogens in the α positions (up to five), the weaker the base necessary for dehydrohalogenation. Sodium hydroxide in methanol will polymerize tetrachloro‐ p ‐xylene, while potassium tert ‐butoxide in refluxing p ‐xylene is necessary to polymerize α‐chloro‐ p ‐xylenes. Stilbenes are formed when α‐halo‐ p ‐xylenes are reacted with potassium tert ‐butoxide in polar solvents such as dimethyl sulfoxide.