The preparation method of 4,5-dibromophthalic acid

Abstract

The invention discloses a preparation method of 4,5-dibromophthalic acid, the steps are as follows: (1) after dissolving phthalic hydrazide in glacial acetic acid, adding N-bromosuccinimide ( NBS), heated to 80~100℃ and reacted for 0.5~1 hour. After the reaction was completed, the system was cooled to room temperature and then poured into ice water to precipitate a solid, which was filtered to obtain dibromophthalhydrazide and the filtrate; (2) Bromophthalohydrazide was dissolved in aqueous sodium hydroxide solution, heated to 60-70°C for hydrolysis reaction, after the hydrolysis reaction, the pH of the hydrolysis reaction system was adjusted to 6-7, a white solid was precipitated, filtered and washed with water to obtain 4 ,5‑Dibromophthalic acid. Its advantages are low cost; the two-step products are precipitated in solid form, the reaction is easy to handle, and the product has high purity; it can fully meet the industrial needs of such products and provide sufficient raw materials for downstream chemical products and material research and development.

Description

technical field [0001] The invention belongs to the field of organic synthesis chemistry, and in particular relates to a preparation method of 4,5-dibromophthalic acid. Background technique [0002] Phthalic acid compounds are excellent metal ligands and valuable organic intermediates, and are important raw materials for the synthesis of phthalocyanine compounds. Phthalocyanine has a large π-conjugated aromatic system and is used in sensors, cancer fluorescence therapy, dyes, optical Records, electrochromic smart materials and solar photovoltaic devices are widely used, especially dibromophthalic acid is an urgently needed raw material for the synthesis of bromophthalocyanine compounds, but 4,5-dibromophthalocyanine Formic acid is basically not sold in batches on the market, and the reported synthesis methods are mostly early literature (Chem. Ber., 1884, 17: 2494-2496; J. Chem. Soc., 1952, 4615-4618; J. Amer. Chem . Soc., 1942, 64:2639-2641), nitric acid is often used to o...

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Problems solved by technology

[0002] Phthalic acid compounds are excellent metal ligands and valuable organic intermediates, and are important raw materials for the synthesis of phthalocyanine compounds. Phthalocyanine has a large π-conjugated aromatic system and is used in sensors, cancer fluorescence therapy, dyes, optical Records, electrochromic smart materials and solar photovoltaic devices are widely used, especially dibromophthalic acid is an urgently needed raw material for the synthesis of bromophthalocyanine compounds, but 4,5-dibromophthalocyanine Formic acid is basically not sold in batches on the market, and the reported synthesis methods are mostly early literature (Chem. Ber., 1884, 17: 2494-2496; J. Chem. Soc., 1952, 4615-4618; J. Amer. Chem . Soc., 1942 , 64:2639-2641), nitric acid is often used to oxidize at a high temperature of 170°C, the method is backward, and it is not conducive to environmental protection

Secondly, phthalic anhydride is used as raw material to prepare with sulfuric acid and bromine at high temperature, which also has strong corrosion and environmental protection problems. These methods have low yield, large pollution, and are not easy to operate. They have long been unable to meet the batch demand of modern materials.

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