Preparation method for phthalyl chloride, m-phthaloyl chloride and paraphthaloyl chloride

Abstract

The invention relates to a preparation method for phthalyl chloride, m-phthaloyl chloride and paraphthaloyl chloride. In the method, benzene dicarboxylic acid and triphosgene are taken as raw materials and mixed for catalytic reaction in an organic solvent of 1, 2-dichloroethane, the mol ratio for the catalytic reaction is 0.5-0.9, the catalyst is N, the dosage of N-dimethyl formamide is 0.1-0.6 time of the weight of the raw material benzene dicarboxylic acid, the catalytic reaction lasts for 2-5 hours, and the reaction temperature is the reflux temperature of the solvent 1, 2-dichloroethane. Compared with the prior art, the invention avoids using toxic and hazardous thionyl chloride, phosphorus oxychloride and phosgene and the like. Therefore, the invention has the advantages of reasonable process conditions, simple and safe operation, high reaction yield, low manufacture cost and easy realization of industrial production, and has high implementation value, social benefit, economic benefit and environmental benefit.

Description

technical field [0001] The invention relates to a method for preparing o-, m-, and terephthaloyl dichlorides, in particular to a method for preparing o-, m-, and terephthaloyl dichlorides by using solid phosgene as a chlorinating agent to react with o, m, and terephthalic acid According to the method, the obtained products of o-, m-, and terephthaloyl chlorides can be used in fields such as macromolecules, medicines, and pesticides. technical background [0002] Phthaloyl chloride is one of the main monomers for the synthesis of polyarylamide, polyesteramide, polyarylate, polyarylsulfone and other high-strength films and high-temperature-resistant materials. It is widely used in pesticides, medicines, dyes and pigments. Among them, phthaloyl chloride is an important starting material for the preparation of plasticizers and synthetic resins, and is also a synthetic structural unit for the synthesis of active ingredients in drugs and pesticides. The uses of terephthaloyl chlo...

AI Technical Summary

Problems solved by technology

[0003] At present, phthalic anhydride or phthalic acid is generally used as raw material to react with chlorinating reagents to prepare corresponding phthaloyl chloride. There are many kinds of chlorinating agents that can be selected, including thionyl chloride, phosgene, pentachloride Phosphorus, phosphorus trichloride, chlorinated hydrocarbons, trichlorotoluene, etc., but the aforementioned chlorination agents all have disadvantages in the preparation of phthaloyl chloride, wherein the reaction temperature of the thionyl chloride production process is about 80 ° C, and the reaction The time is slightly different with the type and quantity of the catalyst, generally 8-12 hours, and the yield is about 85%, but the product quality is low, the purity is not high, and the melting point of terephthaloyl chloride is only about 80°C , cannot be directly used in the synthesis of man-made fibers, and often requires several times of vacuum distillation to reach the specified target, and this method has certain corrosiveness to equipment during post-treatment, resulting in high production costs. , thionyl chloride is highly irritating, leading to harsh operating environments; phosgene is a highly toxic gas with low boiling point and high volatility, which is extremely dangerous in the process of use, transportation and storage, and various strict A little carelessness will cause catastrophic accidents; phosphorus pentachloride has a strong chlorination ability, many side reactions, and the product is not easy to separate and purify, and phosphorus pentachloride is easy to absorb moisture in the air and Decompose and release hydrogen chloride gas; the application of phosphorus trichloride is less, the reaction needs higher temperature and longer time, the process operation is relatively complicated, and the yield is low, and also generates phosphorus oxychloride by-products, phosphorus trichloride and Phosphorus oxychloride is also more corrosive to equipment

The catalysts used in the chlorinated hydrocarbon method include zinc powder, aluminum powder, iron powder, anhydrous zinc chloride, ammonium chloride, ferric chloride, etc. The disadvantage of this method is that the chlorinated hydrocarbons used do not meet environmental protection requirements, and the use of Lewis When acids such as zinc chloride, ferric chloride, etc. are used as catalysts, the mixture of Lewis acid and the generated organic by-products is difficult to handle, and the separation operation cost is high

The shortcoming of trichlorotoluene method is to generate benzoyl chloride by-product and Lewis acid, and aftertreatment is comparatively complicated; In ester chlorination method, chlorine is used as chlorination agent, but due to the production process of raw material dimethyl terephthalate Methanol is consumed, the reaction temperature is higher, the production cycle is long, and ultraviolet light irradiation is often used in the reaction process, the release of tail gas in the reaction process is also relatively large to environmental pollution, and phosgene is released; xylene chlorination method The main feature is that it starts from p-xylene and does not need to go through the acid stage

[0005] Although there have been relevant research reports on the preparation of acid chloride compounds by the reaction of solid phosgene and carboxylic acid, the chlorination technology of carboxylic acid using solid phosgene as chlorinating agent is not yet mature.

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