Effect of ZnCl2 on the Spontaneous Copolymerization of Acrylonitrile with Substituted 1,3-Dienes

Autor:	Anne Buyle Padias, H. K. Hall, Michael G. Mikhael
Rok vydání:	1994
Předmět:	Reaction mechanism Polymers and Plastics Diene Chemistry Organic Chemistry Concentration effect Cycloaddition Inorganic Chemistry chemistry.chemical_compound Polymer chemistry Materials Chemistry Copolymer Lewis acids and bases Acrylonitrile Isoprene
Zdroj:	Macromolecules. 27:7499-7503
ISSN:	1520-5835 0024-9297
DOI:	10.1021/ma00104a001
Popis:	Acrylonitrile was allowed to react with three substituted hydrocarbon 1,3-dienes, namely, 2,3-dimethyl-1,3-butadiene (DMB), 4-methyl-1,3-pentadiene (MPD), and isoprene (IP) in 1,2-dichloroethane in the presence of various amounts of ZnCl 2 at different temperatures. Alternating copolymers and [4+2] cycloadducts formed spontaneously. The structure of the diene and its electron-rich character control the product distribution. In the reaction of DMB and AN, raising the temperature and increasing the ZnCl 2 concentration enhance the cycloaddition process, while the maximum yield of the copolymerization is at 45°C. At higher temperatures, no copolymers formed. With MPD, only copolymer is formed because the two terminal methyl groups preclude the concerted [4+2] cycloaddition. IP is less reactive than DMB, and the overall yields are lower. These results are in agreement with a postulated mechanism involving competition between a π-allyl 2-hexene-1,6-diradical and concerted cycloaddition. A H-transfer mechanism is suggested to explain the lack of copolymer for DMB/AN or IP/AN at higher temperatures and ZnCl 2 concentrations
Databáze:	OpenAIRE
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