Synthesis and polymerization of 1- and 2-cyano-1,3-butadienes

1-Cyano-1,3-butadiene and 2-cyano-1,3-butadiene were prepared and designated 1-cyanoprene and 2-cyanoprene, respectively. These compounds, and their intermediates, were characterized by their infrared and proton magnetic resonance spectra. Their polymerizations with lithium or aluminum alkyl catalysts are described. The synthesis of these monomers involves a thermal cracking process (400–500°C). The yield of monomer by this process depends on the positions of the cyano and acetoxy groups in the butene intermediate; if the cyano and the acetoxy groups are attached to the same allylic carbon, a low monomer yield is obtained. The polymers of 1-cyanoprene are the results of 1,4-enchainment (cis and trans) and are amorphous; the polymers of 2-cyanoprene may involve 1,4-enchainment but are partially crystalline. Both of these polymers are thermoplastic.