Comment on the origin of benzenecarboxylic acids in pyrolysis methylation studies

The presence of benzenecarboxylic acid methyl esters in thermochemolysis or pyrolysis products of humic acids, produced in the presence of tetramethylammonium hydroxide (TMAH), has recently been attributed to the existence of benzenecarboxylic acid moieties in the original materials being examined by this new technique for structural elucidation. Our studies of wood and model compounds, materials free of carboxylic acid-containing structures, by this method indicate that certain benzenecarboxylic acids are produced by the TMAH reagent in the course of reaction at elevated temperatures. This indicates that one should exercise due caution in interpreting the presence of these benzenecarboxylic acid methyl esters as pre-existing structural humic acids.