Method for preparing 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate

The invention discloses a method for preparing 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate. The method includes the following steps: first, adding cyanuric acid trisodium salt and 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl into a polar aprotic solvent, second, adding a phase transfer catalyst, third, heating the mixture to 100-120 DEG C and leaving the mixture to carry out thermal reaction for 8-20h under the protection of nitrogen, fourth, cooling the mixture to 50-60 DEG C and filtering out the salt, fifth, distilling off the solvent under a pressure of 0.005-0.015MPa, sixth, adding a non-polar solvent and water for solution and washing, seventh, distilling off residual water and a large part of solvent after settlement water diversion, eighth, adding methyl alcohol for dissolution, ninth, adding activated carbon for decoloration, tenth, cooling filtrate to achieve separation by crystallization after hot filtration, and eleventh, carrying out filtration to obtain the 1,3,5-tris(4-tert-