Cyclodimerizations and Copolymerizations of Vinyl Ketones with Vinyl Monomers

Diels-Alder reactions (cyclodimerizations) of chloromethyl vinyl ketone (CMVK) and methyl isopropenyl ketone (MIPK) leading to 2,3-dihydropyran derivatives have been studied kinetically in connection with their radical polymerization. The activation enthalpies and entropies obtained for the cyclodimerizations of CMVK and MIPK were 48.0 and 68.5 kJ/mole and −209 and −177 J/°C-mole, respectively, at 90°C. The rate constants of the cyclodimerizations were almost independent of the solvents used. The reactivities of vinyl ketones as diene or dienophile were also studied for CMVK, MIPK and methyl vinyl ketone in comparison with their structures. The cocyclo-dimerization and copolymerization of CMVK with various vinyl monomers were also investigated. The results obtained are discussed from the viewpoint of the structures and reactivities of these monomers.