2,5-dimethyl-1,4-phenylenediamine preparation method

Abstract

The invention relates to a preparation method of 2,5-dimethyl-1,4-phenylenediamine. The method is characterized in that aniline substances are used as a raw material and are made into 2,5-dimethyl-1,4-phenylenediamine through a diazotization reaction, a coupled reaction, a hydrogenolysis reaction and purification treatment. According to the invention, the main and the auxiliary raw materials are cheap and easy to obtain, the reaction steps are relatively few, the yield is high, the operation is simple and convenient, and the method is used for further replacing the old technology to realize and develop the novel industrialized production of the product; the aniline substances are reclaimed to be still used as auxiliary raw materials for preparing aniline diazonium salt, so that cost and pollution are reduced, circular economy is produced, and cleaner production is realized; the quality of the obtained product is improved greatly, and the content is far more than the old product, especially an exported product of the content of 75%; the prepared product can not only be used for dye and paints, but also can expand using functions of a high-performance material monomer.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a preparation method of 2,5-dimethyl-1,4-phenylenediamine. Background technique [0002] 2,5-Dimethyl-1,4-phenylenediamine, also known as 2,5-dimethyl-p-phenylenediamine, is included in the 06 new material technology field (serial number 88, customs Product No. 29215190, yellow or green-yellow powder, content ≥75%). Since 2,5-dimethyl-1,4-phenylenediamine contains two para-amino groups, it is firstly used to prepare monomers of rigid linear polyamide and polyimide, intermediate materials for preparing chemical pigments, and use For hair dye ingredients. Synthesis of 2,5-dimethyl-p-phenylenediamine as an intermediate of organic pigments, N,N'-bis-acetoacetyl-2,5-dimethyl-1,4-phenylenediamine, and further preparation of condensation pigments Yellow 95 (Cromophtal GR) has a stable demand for high-end inkjet printing; and monomers for the preparation of modif...

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Problems solved by technology

[0003] Regarding the synthesis route of 2,5-dimethyl-1,4-phenylenediamine, there are currently relevant literature reports at home and abroad: p-xylene is used as raw material, and 2,5- Xylene, react with acetic anhydride, nitrate with mixed acid, and alkaline hydrolyze with NaOH to obtain 2,5-dimethyl-4-nitroaniline, and finally react with SnCl 2 / HCl reduction to obtain the product 2,5-dimethyl-1,4-phenylenediamine (Dye Industry, 2000, 37 (4): 16-18), but the synthetic route adopted is complicated and the product yield is relatively low Low

[0004] Patent CZ9501363A3 uses p-aminobenzenesulfonic acid as a raw material, under the action of sodium nitrite, a diazonium reaction occurs, and then coupled with 2,5-dimethylaniline, and the product 2,5-dimethylaniline is obtained by reduction of hydrosulfite -1,4-phenylenediamine, but the by-products produced by this route will cause difficulties in the recovery of aminobenzenesulfonic acid, and there are also problems such as the high cost of reducing agent hydrochloric acid

[0005] In addition, there are also literature reports using 1,4-dibromo-2,5-xylene in Cs 2 CO 3 and Bu 4 The product 2,5-dimethyl-1,4-phenylenediamine (JOC 2012,77:6653-6656) was obtained by pressure ammonolysis reaction with ammonia water at 110-140°C under the catalysis of NBr. Although the purity of the product obtained by this method is Higher, but the reaction time is longer, and the raw material 1,4-dibromo-2,5-xylene and the cost of the catalyst are high, thus losing the value of industrial development

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