Electrochemical polymerization of dicarboxylic acids-II. Oligomers and side products in the polymerization of adipic acid

The electrochemical polymerization of adipic acid in methanol and in methanol-pyridine (1:1) via the Kolbe reaction {A figure is presented} was investigated as regards the oligomeric and side products. GC-MS, i.r. and NMR were used to identify the many products. Gaseous and volatile compounds were identified as C₄ and C₈ hydrocarbons besides λ- and δ-valerolactones. The less volatile compounds were separated on silica gel columns to fractions, viz. that eluted by heptane which contained hydrocarbons, that eluted by benzene which contained ether and ester groups and that eluted by methanol which contained higher oligomeric products containing oxygen. Four types of hydrocarbons were formed, viz. n-alkanes, n-alkenes, x-alkenes (the place of the double bond is not known) and cycloalkanes. Saturated and unsaturated oligomeric mono- and di-carboxylic acids were also formed.