STUDIES OF POLYMERS AND POLYMERIZATION: V. THE INFLUENCE OF METHYL AND PHENYL SUBSTITUTION ON THE POLYMERIZABILITY OF BUTADIENE

Abstract

A number of methyl- and phenyl- substituted butadienes were prepared and polymerized by different means under properly comparable conditions. The velocity and extent of polymerization were measured and the influence of the number and position of substituent groups on these two factors are discussed. The extent of polymerization depends upon the number of unsubstituted hydrogen atoms on the terminal carbon atoms of the conjugated system, and the ability of a conjugated diene to form a synthetic rubber depends upon the presence of at least three of these hydrogen atoms. The presence of phenyl substituents favors a tendency to dimer formation. The dimers from all the hydrocarbons were unsaturated ring compounds. 1-Phenyl-3-methyl butadiene and 1-3-diphenyl butadiene were found to polymerize spontaneously. The action of methyl magnesium iodide on benzalacetophenone results in both 1-2 addition to yield 1-3 diphenyl buten-1-ol-3, and in 1-4 addition to yield 2-4-diphenyl butanone-4, the former reaction preponderating.