Analyses of synthetic resins by application of 13C NMR

Abstract In a study of synthetic resin analysis, 13C NMR spectra of phenol resins were measured, and the chemical shifts of the various carbon sites compared with the resins' reactivity with formaldehyde. Measurements were made with phenol, para‐substituted phenols, chlorophenols, hydroxytoluenes, dimethyl(hydroxy)benzenes, dihydroxybenzenes, and dihydroxytoluenes. The chemical shifts of these phenols were compared with calculated shifts obtained by using a simple summing rule. These chemical shifts are closely related in magnitude to the reactivity of the phenols with formaldehyde. For example, resorcin has the greatest reactivity with formaldehyde of the above‐mentioned phenols and this experimental result agrees well with the measured large 13C chemical shifts for resorcin.