Polymerization of 1‐methylene‐4‐vinylcyclohexane by a cyclic polymerization mechanism,

Abstract

Abstract1‐Methylene‐4‐vinylcyclohexane was prepared by the following reaction sequence: (1) conversion of 4‐methylene‐cyclohexane methanol to the tosylate, (2) oxidation of the tosylate to 4‐methylenecyclohexane carboaldehyde by the method of Kornblum, and (3) reaction of the aldehyde with the ylide from triphenylmethylphosphonium bromide in a Wittig reaction to produce the diene. Polymerization of 1‐methylene‐4‐vinylcyclohexane was attempted with the use of free radical, anionic, cationic, and Ziegler‐type initiators. Polymers were obtained from the cationic (boron trifluoride) and Ziegler (titanium tetrachloride and triethylaluminum complex)‐initiated reactions. The polymer obtained by polymerization of this monomer with gaseous boron trifluoride as the initiator led to a solid polymer which was soluble in a number of organic solvents and had a softening temperature of 150°C. The infrared spectrum of this polymer gave absorption bands for terminal unsaturation. NMR analysis indicated that the unsaturation ratio was one double bond per two monomer units. The NMR analysis also indicated that this unsaturation was due to vinyl rather than methylene groups. Polymerization of this monomer by use of a Ziegler catalyst (titanium tetrachloride and triethylaluminum) led to a solid polymer of which 10% was soluble in a number of organic solvents. Although the infrared spectrum of this polymer indicated the presence of some terminal unsaturation, an NMR analysis indicated only an extremely small amount of residual unsaturation. The essential absence of unsaturation in this linear polymer supports an intramolecular interaction in this monomer, since Ziegler‐type initiators do not ordinarily initiate polymerization of the isobutylene type. These results can be interpreted as additional evidence for the nonbonded interaction concept as a driving force to cyclic polymer.