Study of the condensation products of abietic acid with formaldehyde

Abietic acid and paraformaldehyde, taken in various molar ratios, were condensed in acid catalysis (p-toluenesulfonic acid). Toluene was used both as reaction medium and carrier for aqueous condensate. The obtained polymeric products (resins) were characterized by determination of acid number, melting point, molecular weight and viscosity. Spectral methods, e.g. I. R. and ¹H-NMR, were also used in the same scope. The experimental data evidence the fact that abietic acid is a substance with a functionality of minimum 3 as against formaldehyde. There have been obtained some condensation products with three-dimensional structure and low molecular weight. The polymerization average degree of the resins was found to be 3, although some fractions with polymerization average degree of 6 have been observed. The chemical bonds established between the structural units can be of both methylenic and dimethylene ether type, depending on the molar ratio of reacting substances.