Method for preparing 4-tert-octyl-2,6-dicumyl phenol

The invention relates to the method for preparing 4-tert-octyl-2,6-dicumyl phenol. The method is used for solving the problems in the existing 4-tert-octyl-2,6-dicumyl phenol production processes that the reaction selectivity is poor and disproportionation occurs at high temperatures. The method comprises the steps: (1) adding 4-tert-octyl phenol, metallic aluminum and rare earth chloride into a reactor, heating to carry out reaction until no bubble is discharged, carrying out heat preservation, adding ionic liquid into the reaction product, and uniformly mixing the ionic liquid and the reaction product, thereby obtaining a mixture; (2) dropwise adding alpha-methyl styrene into the mixture, and continuing to carry out reaction after alpha-methyl styrene is dropwise added completely, so as to obtain a reaction mixture; and (3) adding dilute sulfuric acid into the reaction mixture, adding an organic solvent into the dilute sulfuric acid added reaction mixture, precipitating to separate a water layer, then, directly cooling to precipitate crystals, filtrating the precipitated crystals to obtain a crude product, and recrystallizing the crude product with an ethanol-water mixed solvent, thereby obtaining 4-tert-octyl-2,6-dicumyl phenol. According to the method, the selectivity of 4-tert-octyl-2,6-dicumyl phenol is greatly improved. 4-tert-octyl phenol is effectively prevented from being disproportionated into phenol. The method is used for preparing 4-tert-octyl-2,6-dicumyl phenol.