Usually 4-nitrophenol exists as a mixture of these two forms.

Genotoxicity and carcinogenicity of 4-nitrophenol are not known.

The product of the reaction, 4-nitrophenol, is yellow at alkaline pH and can be measured by photometry.

Hydrolysis, which deactivates the molecule, occurs at the aryl ester bond resulting in diethyl thiophosphate and 4-nitrophenol.

In peptide synthesis, carboxylate ester derivatives of 4-nitrophenol may serve as activated components for construction of amide moieties.

Diethyl dithiophosphoric acid is chlorinated to generate diethylthiophosphoryl chloride, which is then treated with sodium 4-nitrophenolate (the sodium salt of 4-nitrophenol).

In solution, 4-nitrophenol has a dissociation constant (pKa) of 7.16 at 22 C. Solution of 4-nitrophenol alone appears colorless or pale yellow, whereas its phenolic salts tend to develop a bright yellow color.