A kind of method for preparing benzoin product by circulation of mother liquor

Abstract

The present invention is a method of preparing a scent product for a mother liquid circulation, which is the field of chemical products preparation technology.In the proportion, the reaction parent, phenyldehyde, water, hydrochloric acid, cationic surface active agent, phase transfer catalyst, dispersant, and inorganic salt are obtained during the reaction of the reaction of the incense product reaction process.Stir, heat up to 45-65 ° C, add cation surfactant agent, and thermal insulation reaction is 1.0-2.0h; add cation surface active agent to 55-70 ° C, the insulation reaction is 1.5-2.5h, until the reaction is over;Rough products, washed with ethanol solution, dry, and white crystal products; separated filtrates reflect the mother liquid, collect, weigh, and use it as a reaction solvent cycle.The present invention has the characteristics of simple production process, high product revenue, good quality, low production cost, and facilitating industrial production.

Description

technical field [0001] The invention relates to a technical method for preparing benzoin products by circulating mother liquor, and belongs to the technical field of chemical product preparation technology. The chemical structural formula of benzoin product is: [0002] Background technique [0003] Benzoin is an important organic synthesis product, which is widely used as a photosensitizer for photosensitive resins and an anti-cratering agent for powder coatings; in addition, benzoin is also widely used as an intermediate for synthetic dyes and synthetic medicines. [0004] The synthetic method of benzoin is that benzaldehyde is used as a raw material, methanol or ethanol solution is used as a reaction solvent, sodium cyanide is used as a catalyst, and benzaldehyde is generated by bimolecular condensation reaction. [0005] [0006] "Journal of Hubei University for Nationalities (Natural Science Edition)" Vol. 26 No. 2, "Packaging Engineering" Vol. 25 No. 6, "Journal...

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Problems solved by technology

[0006] "Journal of Hubei University for Nationalities (Natural Science Edition)" Vol. 26 No. 2, "Packaging Engineering" Vol. 25 No. 6, "Journal of North China Coal Medical College" Vol. 25 No. 6, "Chemical Bulletin" 2002 No. Phase 1 discloses that benzaldehyde is used as a raw material, methanol or ethanol solution is used as a reaction solvent, and vitamin B1 is used as a catalyst to carry out bimolecular condensation reaction under alkaline conditions to prepare benzoin products. The disadvantages are that the reaction yield is low and the production cost higher

[0007] Volume 6, No. 5 of "Fine Chemical Intermediates" discloses the preparation of benzoin products through benzaldehyde condensation reaction using thiazole salts as catalysts. For example, benzaldehyde and thiazole salts are added in proportion to the reaction kettle. , carry out bimolecular condensation reaction, after the reaction is finished, cool and precipitate crystals, filter with suction, wash with ice absolute ethanol, and vacuum-dry to obtain the benzoin product of white needle-like crystals. The disadvantage is that the reaction yield is low and the production cost is relatively high

[0008] Using methanol solution as a reaction solvent, sodium cyanide as a catalyst, and benzaldehyde performing a bimolecular condensation reaction to generate benzoin is a technology commonly used in industrial production processes, and it is also the only feasible industrial production technology compared to the above-mentioned disclosed technologies; The further improved technology is to use 50-60% low-concentration methanol solution, add quaternary ammonium salt cationic surfactant to improve the mass transfer effect of the phase interface, improve the conversion rate of raw materials and the yield of products, the technical method exists The main problem is that after the condensation reaction is over, the product obtained is not a crystalline substance with a relatively large particle size, but a form of fine crystals mixed in the reaction solvent to form a reaction mixture. After cooling, a part of the microcrystalline product aggregates and forms Granular agglomerated product, which contains a lot of impurities; another part of the microcrystalline product is directly mixed in the reaction solvent to form a slurry-like solid-liquid mixture, and the reaction products in the two states are blended to form the final reaction mixture. Carry out solid-liquid separation to extract the required solids as benzoin products; because the slurry-like solid-liquid mixture causes great difficulties in the separation of products, the separation efficiency is very low in the case of forced separation. In addition, the separated solids are filtered The cake contains more impurities and the mother liquor of the encapsulation reaction, forming a stronger wet filter cake, which will form a harder solid block after drying and removing the solvent, which needs to be crushed by a pulverizer to form a light yellow fine powder benzoin product

[0009] The poor quality of the benzoin products produced by the above-mentioned process technology is justifiable. The main reason is that benzaldehyde generates two substances during the condensation reaction, one is benzoin, and the other is mixed with various by-products formed during the reaction process. The oily substance of the non-solid compound, which is brownish red, is mixed with the benzoin product in the reaction mixture from the beginning to the end of the reaction process. When the crystallite aggregate of the benzoin product is formed, the by-product will enter the benzoin aggregate. Or adhere to the surface of the aggregate, washing only removes the colored impurities on the surface, but the internal ones still exist, resulting in the color of the benzoin product obtained after being crushed by a pulverizer is light yellow, and it cannot be eliminated by repeated washing of the product, so The purity of benzoin is low, about 95-98%; the melting point is low, usually less than 132°C

Additives used in powder coatings have poor anti-aging performance under light and heat aging conditions, and the further application of the product is limited

[0010] In order to obtain high-quality benzoin products, it is usually necessary to recrystallize and refine the light yellow fine powder benzoin products to obtain white benzoin particle crystal products, but due to the large dissolution loss, the final yield of the product is low; and the process increases , increased solvent consumption, increased energy consumption, and high production costs

[0011] As we all know, methanol has the disadvantages of toxicity, flammability, explosion, and volatility.

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