The polymerization of vinyl mesityl ketone was attempted in order to study the effect of steric hindrance on this type of reaction. Vinyl mesityl ketone was prepared from mesitylene and P- chloropropionyl chloride by the Friedel-Crafts method. Apparently the P- chloropropiomesitylene which might have been expected spontaneously lost hydrogen chloride. The vinyl ketone absorbed bromine to give a dibromide from which it could be ...