can't read?
4-Formylbenzoic acid is an organic compound]] with the formula OCHC6H4CO2H. It consists of a benzene ring substituted with both an aldehyde and a carboxylic acid functional groups.
F 1519 (OTTO) 4-Formylbenzoic acid, puriss, 99% Cas 619-66-9 - 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.