Synthesis
4'-Hydroxy-4-biphenylcarboxylic acid may be prepared by hydrolysis of the compound represented by the following general formula (2).
In formula 2, R1 denotes an alkyl, cycloalkyl or aryl radical containing 1 to 6 carbon atoms;
R denotes hydrogen or alkyl;
X denotes a leaving group selected from chlorine, bromine, iodine, mesyl, benzenesulfonyl, or toluenesulfonyl;
the quaternary ammonium group denotes an ammonium group bearing three identical or different alkyl groups or a pyridinium group. Hydrolysis is conducted in an alkaline aqueous solution or a mixed solution of an alkaline aqueous solution and an organic solvent. The alkali used for hydrolysis is selected from the group consisting of NaOH, KOH, CsOH, Na₂CO₃, K₂CO₃, and Cs₂CO₃-4-biphenylcarboxylic acid. The hydrolysis reaction is conducted at temperatures between 60 and 100°C. Compounds of formula (2) are prepared by reacting compounds of formula (3) with tertiary amines.
