Studies in pyrolysis. Part XXVI. Model systems for the pyrolysis of poly(ethylene fumarate) and allied polyesters

Abstract

Pyrolysis of ethyl maleate leads to cis→trans inversion, with concurrent alkyl–oxygen scission (A¹; predominating), acyl–oxygen scission (B²), and decarboxylation (C²). For methyl maleate, A¹ scission is structurally precluded; there is cis→trans inversion, with concurrent B² and C² scission. Ethylene diacrylate and dimethacrylate both undergo a predominating double C² scission, in competition with A¹ scission and a minor B² scission: the products of the primary A¹ scission partially interact to give an ethylidene diester, followed by disproportionation and further breakdown. All pyrolyses were at ca. 450–500° in the vapour phase. The bearing of these results on the pyrolysis of poly(ethylene fumarate) is discussed.