Method for preparing 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride

Abstract

The invention relates to a method for preparing 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride. The method comprises the following steps: step 1, mixing 4, 4'-(hexafluoroisopropenyl) di-o-xylene,a metal ion catalyst, a cocatalyst and a solvent to form a homogeneous solution; step 2, injecting the prepared solution into a continuous reactor at a certain speed through a pump, and introducing corresponding equivalent pure oxygen into the reactor; step 3, enabling a reactant solution and pure oxygen to react in the continuous reactor, carrying out separation from the continuous reactor afterstaying for a certain period of time, and enabling a product to enter a gas-liquid separation tank after passing through a cooling module; step 4, separating the product solution to obtain 4, 4 '-(hexafluoroisopropenyl) diphthalic acid (6-FTA); and step 5, performing refining to obtain 4, 4'-(hexafluoroisopropenyl) diphthalic anhydride (6-FDA).

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for preparing 4,4'-(hexafluoroisopropenyl) diphthalic anhydride. Background technique [0002] Polyimide has the advantages of high strength, high dielectric constant, and non-toxicity. It is increasingly used in the electronics industry and is the substrate material for flexible circuit boards. Ordinary polyimide film is yellow and has a light transmittance of less than 70%, so it cannot be used as a flexible display cover. The introduction of fluorine-containing groups into polyimide polymer monomers can effectively improve its light transmittance, and prepare polyimide transparent films that meet the requirements of folding screens. Among the many transparent monomers, 4,4'-(hexafluoroisopropenyl) diphthalic anhydride (6-FDA) is the most critical one. [0003] The current preparation route of 6-FDA is mainly prepared by oxidation and dehydratio...

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Problems solved by technology

[0006] Chinese patent CN101696199A discloses a process for preparing 6-FDA by oxidizing 6-FXP with potassium permanganate, but the oxidizing operation of potassium permanganate is complicated, and a large amount of manganese dioxide is produced in the process, which requires a large amount of solvent and acid and alkali, and there are many wastes. There are still big problems in actual industrial production

However, these reaction processes are mainly carried out around air oxidation in autoclaves. Nitrogen, which accounts for 80% of the reaction gas, cannot participate in the reaction and needs to be discharged, which brings great environmental protection and process problems;

[0008] The process conditions described in the above patents still have various defects, such as many wastes, high reaction risk coefficient, complex operation process, insufficient process stability, and difficulty in realizing industrial scale-up, etc.

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