A kind of preparation method of tetrabromophthalic anhydride

Abstract

The invention relates to a preparation method of tetrabromophthalic anhydride. The preparation method comprises that fuming sulphuric acid, bromine and phthalic anhydride as raw materials undergo a reaction in the presence of a composite catalyst under control of a bromine dropwise addition rate and temperature and a later-stage reaction temperature to produce a product mother liquid, the product mother liquid is subjected to suction filtration, water is added into the filter residue, the filter residues are washed through stirring under control of water washing indexes so that a qualified product is obtained, and the qualified product is subjected to centrifugation and drying so that a finished product is obtained. Compared with the prior art, the preparation method has the characteristics of high product purity and low sulfate radical content.

Description

technical field [0001] The invention relates to the field of flame retardant synthesis, in particular to a preparation method of tetrabromophthalic anhydride. Background technique [0002] Tetrabromophthalic anhydride, also known as tetrabromophthalic anhydride, is an organic brominated flame retardant with a light yellow powder appearance. It can be used as a reactive flame retardant and can be used for flame retardant of polyester resin and epoxy resin. , because of its excellent thermal stability, it can also be used in engineering plastics, and can also be used as an additive flame retardant for flame retardancy of PS, PP, PE, and ABS resins. [0003] At present, the synthesis routes of tetrabromophthalic anhydride include: chlorosulfonic acid bromination method, hydrogen peroxide method, oleum bromination method and oxidation method. Although the chlorosulfonic acid bromination method has a high yield, its raw materials are expensive, the reaction time is long, the tox...

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Problems solved by technology

Although the chlorosulfonic acid bromination method has a high yield, its raw materials are expensive, the reaction time is long, the toxicity is high, and the operation is difficult; the hydrogen peroxide method has the advantages of short reaction time and less consumption of bromine, but the reaction needs about 70% concentration Hydrogen peroxide; the newly developed oxidation method requires high temperature and high pressure, high requirements for equipment, and low reaction yield; the oleum bromination method has the characteristics of cheap raw materials, low toxicity, and relatively simple solvent recovery. Therefore, four domestic and foreign The production of bromophthalic anhydride is mostly produced by the oleum bromination method

The traditional fuming sulfuric acid bromination method for preparing tetrabromophthalic anhydride generally has a product purity of about 94% and a sulfate content of about 0.2%. There are problems such as low preparation purity and high sulfate content.

In order to solve the above problems at present, some methods of preparing tetrabromophthalic anhydride with oleum bromination method have appeared. The bromination reaction of these methods is generally to add bromine dropwise while heating up, and the initial temperature of the bromination reaction is controlled at 90 ° More than above, insulation reaction is about 150 °, and these methods temperature is higher, high temperature energy consumption is high on the one hand, bromine boiling point is low, and temperature is too high to the consumption of bromine; Wrapped inside the product, it is inconvenient to remove. In order to reduce the sulfate content in the product, it needs to be post-treated by crushing, acid-base method, etc., which is troublesome to operate and increases production costs.

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