Synthesis of unsaturated polyesters from dipotassium salts of cis‐aconitic, itaconic and mesaconic acids and 1, 4‐dibromobutane

Abstract

AbstractThe polycondensation of dipotassium salts of cis‐aconitic, itaconic and mesaconic acids and 1, 4‐dibromobutane in 1‐methyl‐2‐pyrrolidone at 105°C led in all the cases to the formation of an unsaturated copolyester containing at least three different units: butylene itaconate, butylene mesaconate and butylene citraconate units. At the equilibrium, the relative molar portions of the three units were found to be equal to 36, 59, and 5%, respectively. The polycondensation of the cisaconitic acid salt was accompanied by a decarboxylation reaction which excluded the possibility of preparing unsaturated polyesters with pendant carboxylic acid groups. The study of model reactions carried out with hexyl bromide did not allow us to determine the structure of unexpected units resulting from side reactions occurring only in the polycondensation of cis‐aconitic and itaconic acid salts.