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Preparation method of 4-bromophthalic acid

A technology of phthalic acid and phthalic anhydride, which is applied in the field of preparation of 4-bromophthalic acid, can solve the problems of easily polluted environment, complicated operation, low utilization rate of bromine, etc., and achieves good selectivity , the effect of high yield and stable product quality

Active Publication Date: 2014-08-13
SINOPHARM CHEM REAGENT
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Problems solved by technology

[0005] The problem to be solved by this invention is to provide a kind of preparation method of 4-bromophthalic acid, to overcome the cumbersome operation of the preparation process of 4-bromophthalic acid in the prior art, easy to pollute the environment, and low utilization rate of bromine lack of

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  • Preparation method of 4-bromophthalic acid

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Comparison scheme
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Embodiment 1

[0025] Slowly add 148g of phthalic anhydride and 40g of sodium hydroxide to 690g of water under ultrasound, place in a 2000ml four-necked reaction flask with a condenser and a thermometer, then add 106g of sodium bromide, and mix well by ultrasound. Heat to 55° C., and slowly drop in an aqueous solution containing 77 g of sodium hypochlorite (concentration: 2 mol / L) under ultrasound, while adjusting the pH value between 5-8 with 5 wt % dilute hydrochloric acid. After feeding, keep warm for 1 hour, then raise the temperature to 80°C for 2 hours. Cool to 2° C., treat under ultrasonic for 0.5 hour, let stand, and filter to obtain 236.2 g of crude product (HPLC purity: 92%).

[0026] The crude product was recrystallized with pure water to obtain 198.3 g of 4-bromophthalic acid, the content detected by HPLC was 98.9%, and the yield was 81%.

[0027] Add hydrochloric acid to the filtrate to acidify to about pH2, cool down, and recover unreacted phthalic acid.

Embodiment 2

[0029] Slowly add 100g of phthalic anhydride and 26g of sodium hydroxide into 600g of water successively under ultrasound, place in a 1000ml four-necked reaction flask with a condenser tube and a thermometer, then add 77g of sodium bromide, and mix well by ultrasound. Heat to 65°C, slowly drop into aqueous solution containing 50g of sodium hypochlorite (concentration: 3mol / L) under ultrasound, and adjust the pH value between 5-8 with 10wt% dilute hydrochloric acid at the same time. After feeding, keep warm for 2 hours, then raise the temperature to 90°C for 1 hour. Cool to -2°C, treat with ultrasound for 1 hour, let stand, and filter to obtain 161.5 g of crude product (HPLC purity: 93%).

[0030] The crude product was recrystallized with pure water to obtain 137.3 g of 4-bromophthalic acid, the content detected by HPLC was 98.6%, and the yield was 83%.

[0031] Add hydrochloric acid to the filtrate to acidify to about pH2, cool down, and recover unreacted phthalic acid.

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Abstract

The invention discloses a preparation method of 4-bromophthalic acid. The preparation method comprises the following steps: by taking phthalic anhydride, sodium hydroxide and sodium bromide as raw materials, evenly mixing phthalic anhydride and sodium hydroxide, under the ultrasonic condition, adding a sodium hypochlorite water solution for reaction, and controlling the pH value of the reaction liquor, to obtain a target product 4-bromophthalic acid. The purity of the 4-bromophthalic acid obtained by adopting the method is more than 98.5%, and the yield is more than 80%, so that the method meets the green and environment-friendly demands. Compared with the prior art, the preparation method has the advantages that the use of high-toxicity and volatile high-price bromine can be avoided, the utilization rate of bromine can achieve more than 90%, the unreacted phthalic acid can be recovered, and thus the green chemical demand is met; under the ultrasonic condition, the method is good in selectivity, the reaction is slow and easy to control, the 4-bromophthalic acid is high in yield, stable in quality and suitable for industrial production.

Description

technical field [0001] The invention relates to a preparation method of 4-bromophthalic acid. Background technique [0002] 4-Bromophthalic acid is an important chemical intermediate, widely used in dyestuffs, polymer industries, etc. Polyurethane with 4-bromophthalic acid as a raw material has been widely used in the microelectronics industry as a packaging material. In recent years, with the increase in the amount of polyamide and phthalocyanine dyes, professionals in this industry have paid attention to 4-bromophthalic acid. [0003] In the prior art, the preparation method of 4-bromophthalic acid uses bromine (Br 2 ) to react, the utilization rate of bromine is low, and the remaining bromine is easy to cause environmental pollution and operational safety hazards. It is necessary to increase equipment to reclaim excess bromine, increase the operation steps, and the utilization rate of its bromine atom is only about 40%. . [0004] In the prior art, "Fine Chemical Inter...

Claims

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Application Information

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IPC IPC(8): C07C63/68C07C51/363
CPCC07C51/083C07C51/363C07C63/68C07C63/16
Inventor 王刚刘征宙陆莉峻干海平施虹
Owner SINOPHARM CHEM REAGENT
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