The invention belongs to the technical field of synthesis of 4, 4-(hexafluoroisopropenyl) diphthalic anhydride, in particular to a synthesis method of 4, 4-(hexafluoroisopropenyl) diphthalic anhydride. The synthesis method has the advantages of easy separation of intermediate products, high yield, less waste and good economic benefit, and a mixed
solvent of
isobutanol and
butyl acetate is adoptedto reduce the
solubility of the product, facilitate the separation of the product and increase the yield. Besides, the Pd / C catalyst is pretreated, a proper amount of
sulfide is added for pretreatment, the
sulfur poisoning resistance of the catalyst is improved, the service life of the catalyst is prolonged, and the application frequency of the catalyst is increased; because nitro compounds contain trace amount of sulfides such as
sulfuric acid and like, catalyst is easily poisoned. In the step 2, an
alumina-
silica gel catalyst is added so that 2, 2-bis (3-amino-4-hydroxyphenyl) molecules canbe adsorbed on the surface of the catalyst in a flat shape, hydroxyl is closer to the surface of the catalyst, and the
amination reaction of hydroxyl is facilitated; in the step 4, a small amount of
urea is added in the cyanolysis reaction to prevent diazonium salt from being oxidized, becoming
tar and other side reactions.