4-Formylbenzoic acid is an important intermediate in the synthesis of terepthalic acid. It reacts with barium carbonate to yield two-dimensional barium(II) coordination polymer.Usually used as reagent during esterification of 2,2,6,6-tetramethyl-4-oxopiperidinyl-1-oxyl to yield 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl 4-formylbenzoate. 4-Formylbenzoic acid is an important intermediate in the synthesis of terepthalic acid. It reacts with barium carbonate to yield two-dimensional barium(II) coordination polymer. Usually used as reagent during esterification of 2,2,6,6-tetramethyl-4-oxopiperidinyl-1-oxyl to yield 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl 4-formylbenzoate.