Study of phenolic resins by PMR spectroscopy with arsenic trichloride as a solvent
Herman A. Szymanski, Albert Bluemle · Journal of Polymer Science Part A General Papers · 1965
Abstract The PMR spectra of several phenolic resins and model compounds related to these resins are reported. Arsenic trichloride as a PMR solvent for the resins is suggested. The PMR spectra of a resin which is linked in the ortho position only is compared to that of a resin where both ortho and para linkages occur. It is shown that the completely ortho‐linked resin gives a phenolic OH signal which does not shift when HCl gas is added, while it does shift if the resin has both ortho and para linkages. This observation is explained by assigning a strong intramolecular hydrogen bond to the ortho‐linked resin. The behavior of the phenolic OH signal when HCl is added can therefore be used to distinguish between ortho and ortho,para‐linked resins. A semiquantitative approach to obtaining average molecular weights is also presented. By integrating the PMR signals of various structural units of the resin it is possible to estimate the relative number and therefore the total number of units of this type in a molecule. The total number is a measure of the molecular weight. Spectral assignments are given for the various types of structural units present in the resins.