Polymerization of β‐cyanopropionaldehyde. V. Anionic polymerization initiated by benzophenone–alkali metal complexes

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Abstract
Anionic polymerization of β‐cyanopropionaldehyde was studied with use of benzophenone‐monosodium, ‐disodium, and ‐dilithium complexes as initiators. The resulting poly(cyanoethyl)oxymethylene was compared with that obtained by cationic and coordinated initiators previously reported. Polymer of higher stereoregularity but lower molecular weight was formed in the present system. The marked influence of the initiator concentration on the polymer yield and stereoregularity is explained on the basis of the difference in the degree of association of the alcoholate ion pair, i.e., the associated ion pair may form stereoregular polymer and the nonassociated or less‐associated ion pair may form a large amount of amorphous atactic polymer. The initiation with benzophenone‐dialkali metal complex was found to be bond‐formation type. Chain transfer with active hydrogen of β‐cyanopropionaldehyde frequently occurs.