Preparation method for diether diphthalimide

Abstract

The invention discloses a method for preparing diether diphthalimide. The method comprises the following steps: step (A): in a reaction kettle, enabling a diphenol raw material to react with one or more of strong base and strong alkali and weak acid salt in a non-polar solvent, such as methylbenzene or o-xylene, under an inert atmosphere; and step (B): enabling a reaction product of the step (A) to react with phthalimide in the presence of an ionic liquid catalyst, to obtain the diether diphthalimide. The method is capable of performing a nucleophilic reaction in the non-polar solvent, addingionic liquid as a phase transfer catalyst, and improving a reaction yield. After ending the reaction, impurities are removed through a water extraction method, and wastewater generation is greatly reduced. The diether diphthalimide is obtained by reducing a pressure and evaporating an organic layer, a process is simple, and an obtained product is high in purity.

Description

technical field [0001] The invention relates to a preparation method of a diether diphthalimide, in particular to a preparation method of a bisphenol A type diether diphthalimide. Background technique [0002] Diether dianhydride is an important monomer for the synthesis of polyetherimide (PEI), and diether diphthalimide is an important intermediate for the synthesis of bisether dianhydride. The traditional method for preparing diether diphthalimide is to first prepare phenoxide in a non-polar solvent, and then synthesize diether diphthalimide by nucleophilic reaction in a polar aprotic solvent. CN1634904A, US4017511A, US4247464A etc. have all reported in aprotic polar solvents such as dimethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide ( In DMAC), diether diphthalimides are prepared by reacting phenoxides with phthalimide compounds substituted by benzene rings. Although such solvents can accelerate the nucleophilic substitution reaction on carbon...

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Problems solved by technology

CN1634904A, US4017511A, US4247464A etc. have all reported in aprotic polar solvents such as dimethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide ( In DMAC), diether diphthalimides are prepared by reacting phenoxides with phthalimide compounds substituted by benzene rings. Although such solvents can accelerate the nucleophilic substitution reaction on carbon atoms, they have high boiling points and poor thermal stability. , volatile, and miscible with water and organic phases, making it difficult to separate the product

In addition, the first step of preparing phenate usually selects non-polar solvents (such as o-xylene, toluene, etc.) to take away the water generated, and the non-polar solvent needs to be evaporated to dryness before adding the polar solvent for nucleophilic reaction. Solvent residues will affect the yield of subsequent nucleophilic reactions

In fact, evaporation of non-polar solvents is a very difficult process. During the evaporation process, phenoxides are prone to agglomeration, wall hanging, uneven heating, and solvent residues, which require high stirring.

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