 4,4'-Biphenol is prepared by dealkylation of the tetra t-butyl derivative, generated by the oxidative coupling of 2,6-di-tert-butylphenol.The oxidative coupling of phenol itself typically gives a mixture of isomers.For example, VCl4 reacts with phenols give 4,4'-, 2,4'-, and 2,2'-biphenols