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CN-116102418-B - Method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride

CN116102418BCN 116102418 BCN116102418 BCN 116102418BCN-116102418-B

Abstract

The invention relates to the technical field of fine chemical synthesis, and particularly discloses a method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride. The method takes dimethylbenzene and trichlorotoluene as raw materials, the dimethylbenzene and the trichlorotoluene are conveyed into a photochlorination reaction tower to heat materials, then the reaction tower is kept under a micro negative pressure working condition to carry out photochlorination reaction, after the reaction is finished, feed liquid is directly conveyed into a reaction kettle, phthalic acid and a catalyst are added for reaction, and finally the reaction feed liquid is separated in a rectification mode to obtain the products of phthaloyl chloride and benzoyl chloride. The invention greatly improves the selectivity of the photochlorination reaction of the dimethylbenzene, inhibits the side chlorination reaction on the ring, can realize the flexible co-production of the m-phthaloyl chloride, the p-phthaloyl chloride and the benzoyl chloride, can flexibly adjust the generation proportion of the phthaloyl chloride and the benzoyl chloride according to the raw material supply and the product demand condition, and greatly improves the production flexibility of the reaction device.

Inventors

  • DING JUNWEI
  • SHAN YULING
  • YU WENLONG
  • LI LI

Assignees

  • 青岛利伟科技服务有限公司

Dates

Publication Date
20260508
Application Date
20230221

Claims (8)

  1. 1. A method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride, which is characterized by comprising the following steps: (1) The method comprises the steps of taking dimethylbenzene and trichlorotoluene as raw materials, conveying the dimethylbenzene and the trichlorotoluene into a photochlorination reaction tower, heating the materials under the protection of dry nitrogen atmosphere, then starting a vacuum device to enable the reaction tower to keep a micro negative pressure working condition, starting a light source, blowing mixed gas of dry chlorine and dry nitrogen from the bottom of the reaction tower, and monitoring the content of dimethylbenzene and 1-5 chlorodimethylbenzene serving as intermediate products in the photochlorination reaction process; The dimethylbenzene is m-dimethylbenzene or p-dimethylbenzene, and the mass ratio of the dimethylbenzene to the trichlorotoluene is 0.2-5:1, and the dry chlorine and the dry nitrogen form mixed gas in a volume flow ratio of 0.1:1-10:1; (2) After the photochlorination reaction is finished, introducing dry nitrogen into a reaction tower for purging, directly conveying the feed liquid into a reaction kettle, adding phthalic acid and a catalyst into the reaction kettle, and heating for reaction; (3) After the reaction is finished, the reaction feed liquid is separated by adopting a rectification mode, and products of benzoyl chloride and benzoyl chloride are obtained.
  2. 2. The method for highly selectively co-producing phthaloyl chloride and benzoyl chloride according to claim 1, wherein in the step (1), the material is heated to 120-160 ℃ to carry out the photochlorination.
  3. 3. The method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride according to claim 1, wherein in the step (1), the light source is an LED light source, the wavelength of the light source is 300-500 nm, and the illumination intensity is 30000Lux-60000Lux.
  4. 4. The method for highly selectively co-producing phthaloyl chloride and benzoyl chloride according to claim 1, wherein in the step (1), an aeration device made of corrosion-resistant material is installed at the bottom of the photo-chlorination reaction column, and a dry atmosphere is blown into the reaction column through the aeration device.
  5. 5. The method for highly selectively producing phthaloyl chloride and benzoyl chloride according to claim 1, wherein the reaction is terminated when the total mass content of dimethylbenzene and intermediate 1-5 chlorodimethylbenzene in the total reaction mass system in the step (1) is less than 0.5%.
  6. 6. The method for highly selectively co-producing phthaloyl chloride and benzoyl chloride according to claim 1, wherein in the step (2), the phthalic acid is isophthalic acid or terephthalic acid, and the addition amount of the phthalic acid is 1.005-1.05 times of theoretical measurement.
  7. 7. The method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride according to claim 1, wherein in the step (2), the catalyst is one or more of ferric trichloride, zinc chloride and aluminum trichloride, the adding amount of the catalyst is 0.1-0.5% of the mass of phthalic acid, and the reaction is carried out after the temperature is raised to 100-140 ℃.
  8. 8. The method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride according to claim 1, wherein in the step (2), the mixture gas of hydrogen chloride and chlorine discharged from a condenser at the top of the photo-chlorination reaction tower is purged, and then enters an absorption tank for containing saturated sodium chloride solution for full washing, and the rest of chlorine is dried and then recycled to the chlorination reaction tower to continue to participate in the reaction.

Description

Method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride Technical Field The invention relates to the technical field of fine chemical synthesis, in particular to a method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride. Background Terephthaloyl chloride (terephthaloyl chloride and isophthaloyl chloride) are an important class of fine chemicals, and terephthaloyl chloride and isophthaloyl chloride of high purity are important monomer raw materials for preparing high performance fiber materials, aramid 1414 and aramid 1313. Benzoyl chloride is also an important fine chemical intermediate, and is widely applied to the preparation of dyes, rubber and plastic assistants and medical intermediates. The main stream synthesis method of the benzoyl chloride is to take toluene as a raw material, obtain trichlorotoluene through side chain chlorination reaction, and then react with benzoic acid to obtain the benzoyl chloride. Although it has been reported in patent (CN 105001077 a) that terephthalic acid and trichlorotoluene are used as starting materials, and terephthaloyl chloride and benzoyl chloride are co-produced by reaction, the method does not involve the synthesis of chlorotoluene, the prepared terephthaloyl chloride and benzoyl chloride have a fixed proportion and use benzoyl chloride as main component (the molar ratio of terephthaloyl chloride and benzoyl chloride in the product is 1:2), and the formation proportion of terephthaloyl chloride and benzoyl chloride cannot be flexibly adjusted according to the raw material supply and the product demand condition. In the mainstream synthesis method of phthaloyl chloride, side chain chlorination reaction of dimethylbenzene is a key step for determining product quality. Compared with the traditional process adopting thionyl chloride, phosphorus trichloride and phosphorus pentachloride as chlorinating agents, the photocatalysis side chain chlorination process adopting chlorine as the chlorinating agents has the advantages of high product yield, simple and convenient operation, less pollution and the like, and is an advanced side chain chlorination process route. In the above reaction, the chlorination reaction on the aromatic ring is a main side reaction, and thus the resultant aromatic ring chlorinated product has a melting point close to that of the side chain chlorinated product, and is difficult to separate. In order to inhibit the chlorination side reaction on the aromatic ring, side reaction inhibitors added with organic amines or other components are mostly adopted in the prior art to improve the side chain chlorination selectivity, but the doping of the inhibitors in a reaction system greatly increases the complexity of the product purification and post-treatment operation. And the inventors have also found in the study of this reaction that the addition of such inhibitors can lead to side effects such as a slowing of the rate of the main reaction. There are also techniques to increase the reaction selectivity by means of segmented chlorination, segmented temperature control, regulation of the illumination intensity, but this undoubtedly increases the complexity of the apparatus and of the operation. It is still challenging to simply and efficiently increase the side chain chlorination selectivity. In summary, the prior art has not provided a method for co-producing phthaloyl chloride and benzoyl chloride based on a high-selectivity aromatic side chain chlorination process. Disclosure of Invention The invention provides a method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride, which has the advantages of simple steps and flexible production, and overcomes the defects of the prior art. The invention is realized by the following technical scheme: A method for high-selectivity co-production of phthaloyl chloride and benzoyl chloride, comprising the following steps: (1) The method comprises the steps of taking dimethylbenzene and trichlorotoluene as raw materials, conveying the dimethylbenzene and the trichlorotoluene into a photochlorination reaction tower according to a certain proportion, heating the materials to a set temperature under the protection of dry nitrogen atmosphere, then starting a vacuum device to enable the reaction tower to keep a micro negative pressure working condition, starting a light source, blowing mixed gas of dry chlorine and dry nitrogen from the bottom of the reaction tower, and monitoring the content of dimethylbenzene and intermediate products 1-5 chlorodimethylbenzene serving as raw materials in the photochlorination reaction process; (2) After the photochlorination reaction is finished, introducing dry nitrogen into a reaction tower to purge residual chlorine and hydrogen chloride, directly conveying the feed liquid into a reaction kettle without separation, adding phthalic acid and a catalyst into the reaction kettle, and heating to a set te