Conjugative Effect of the Pyridazinone Ring on the Polymerizabilities of N-Vinylpyridazinones

Abstract

3-(2-Vinyl)-6-methyl-4, 5-dihydropyridazinone C_2CJ, whose conjugation ability will be expect rather smaller than 3- (2-viny1)-6-methylpyridazinone [1] has been polymerized under various reaction conditions and the results were discussed in terms of the conjugation stability of the pyridazinone ring.
Cationic catalysts ware found to give homopolymer of [ 2 ] but not that of C / J. It was noted that the radical polymerization rate of C_2C J was rather lower than that of C / J (Table 1). Radical copolymerizations of C 2 J and C / D with styrene (St), methyl methacrylate (MMA), and acrylonitrile (AN) have been carried out and the average Q and e values were obtained as O.33 and .23 for 2 and O.54 and 0.54 for, respectively (Table [2]).
Hydrogen bonding parameters (r), using CH₃OD, were determined as 8.0 for 2 J and 9.6 for [2], respectively (Table 4). While, it was observed that Cl J was more effective than C 2 J in accelerating the nucleophilic reaction of sodium n-butyl malonate with n-butyl bromide. All these observations clearly suggest that the pyridazinone ring in Cl J is stabilzed by the effective ring conjugation among the carbonyl group, a pair of electrons on a nitrogen atom and the double bond in the ring.