Thermal degradation of alkylated phenols

Six alkylated phenols were selected as model compounds to study the effects of alkyl substitution, e.g., the blocking of 2,4, or 6 positions and steric shielding of phenolic OH, on thermal stability of phenols. Methylphenols are substantially more stable than tert-butylphenols at temperatures between 350 and 450°C in nitrogen and in air. Thermal degradation of tert-butylphenols appears to be governed by the reactions of tert-butyl groups, including intramolecular interactions between tert-butylgroups and phenolic OH. Alkylated benzofurans produced from tert-butylphenols are likely precursors to the sediment and solids. Coupling of alkylated phenols occurs through alkyl groups via formation of methylene bridges at relatively low conversions.