1,1-Dichlorocyclopropanes, polymerization

Polymerization of 1,1 -Dichlorocyclopropanes. Experiments were first carried out on vinyldichlorocyclopropanes derived from isoprene and butadiene. The polymers obtained were very different from the cyclopropane macromolecular products already described (17), and it was found that cyclopropane participates in polymerization reactions. The study was therefore repeated in the simplest case—i.e., that of saturated cyclopropane monomers. 

The remarkable stability of the 1,1-dichlorocyclopropane system has been recognized ever since the discovery of the carbenes has enabled them to be prepared easily (6). The structure is, however, destroyed by Lewis acids (27). Therefore, polymerizations were first carried out using cationic catalysts and then Ziegler-Natta catalysts which give better results. A first group of monomers consists of 2,2-dimethyl-, 2,2,3-tri-... 

The results obtained have revealed the complexity of the effects involved during the polymerization of the 1,1-dichlorocyclopropanes. Experiments now in progress will undoubtedly indicate the nature of the structures formed. It will then be possible to study in detail the reactions between these monomers and the Ziegler-Natta catalysts. 

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