4-Methoxy-3-nitrobenzoic acid has been studied as a potential antitumor agent as an aniline mustard analog. 4-Methoxy-3-nitrobenzoic acid is also used as a starting reagent for the synthesis of BIPHEP-1-OMe, a precatalyst for the reaction of butadiene to aldehydes.A substituted nitrobenzoic acid reagent for proteomics and organic synthesis research. 4-Methoxy-3-nitrobenzoic acid has been studied as a potential antitumor agent as an aniline mustard analog. 4-Methoxy-3-nitrobenzoic acid is also used as a starting reagent for the synthesis of BIPHEP-1-OMe, a precatalyst for the reaction of butadiene to aldehydes. A substituted nitrobenzoic acid reagent for proteomics and organic synthesis research.