AbstractThe reaction of several dimethyl phenols with formaldehyde in alkaline medium was investigated. The addition products were separated by means of high pressure liquid chromatography and identified using IR and NMR spectroscopy. 2,3‐dimethyl phenol yields four, 2,4‐dimethyl phenol one, 2,5‐dimethyl phenol four, 2,6‐dimethyl phenol one, 3,4‐dimethyl phenol three, and 3,5‐dimethyl phenol five addition products. 3,5‐dimethyl phenol was the most reactive, 2,6‐dimethyl and 2,4‐dimethyl phenols the least reactive species. Rate constants for individual reactions were obtained from the dependence of concentrations on