Steric effect ring-opening polymerization

In recent studies of styrene oxide polymerization reactions we found the phenyl substituent to have a significant Influence on the course of the polymerization process, too. In our particular case, however, the influence is due not only to steric factors, but also to the inductive effects of the phenyl ring, which Influences directly the course of the oxirane ring-opening reaction. 

H2)2 Usually the b"asicity of a heteroc lic compound is affected in the expected order by the inductive effects, conjugation, steric effects, and ring size ( ). The order of basicities is the only estimation of the monomer nucleophilicities, and it reflects fairly well the overall reactivity observed in ring-opening cationic polymerization. 

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