Diflunisal (CAS NO.: ), with other name of ifluoro-4-hydroxy-1,1-biphenyl-3-carboxylic acid, could be produced through many synthetic methods.

This chemical can be prepared in two different ways both starting from 2,4-difluoroaniline (I):

1). The diazotation of (I) with isoamyl nitrite (B) and condensation with anisole (A) produces 4-(2,4-difluorophenyl)anisole (II), which is hydrolyzed with HI in refluxing acetic acid yielding 4-(2,4-difluorophenyl)phenol (III). At last, this compound is carbonated with K₂CO₃ and CO₂ at 175 C and 1300 p.s.i.
2). The diazotation of (I) with isoamyl nitrite (B) and then condensation with benzene in the presence of powdered Cu gives 2,4-difluorobiphenyl (IV), which is acetylated with acetic anhydride by means of AlCl₃ in CH₂Cl₂ yielding 4-(2,4-difluorophenyl)acetophenone (V). The oxidation of (V) with H₂O₂ in refluxing CH₂Cl₂ affords 4-(2,4-difluorophenyl)phenyl acetate (VI), which can be hydrolyzed with NaOH in refluxing water to give the phenol (III).