Preparation method of benzoin product

Abstract

The invention relates to the technical field of organic synthesis and particularly relates to a preparation method of a benzoin product. The preparation method is characterized by taking benzaldehyde as a reaction raw material, sodium cyanide or potassium cyanide as a catalyst and water as a reaction solvent. The preparation method comprises the steps of adding an efficient cationic surfactant, a phase transfer catalyst, a dispersant and inorganic salt into a reaction mixing system, heating up to 60-70 DEG C, carrying out thermal reaction for 1.5h-3.0h, cooling to room temperature after the thermal reaction to obtain a solid-liquid mixture of reaction products, filtering the mixture to separate out a solid product, washing the solid product by an ethanol solution to remove surface impurities, and drying to obtain the white granular benzoin crystal product with the melting point being above 133 DEG C, and the purity being above 99.0%. The product yield is high.

Description

technical field [0001] The invention relates to a technical method for preparing a benzoin product, which relates to the technical field of organic synthesis. Benzoin products specifically refer to the following formula (I): [0002] [0003] (I) [0004] Formula (I) chemical name: diphenylethanolone. Background technique [0005] 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. [0006] The classic synthetic method of benzoin is that benzaldehyde is used as raw material, methanol or ethanol solution is used as reaction solvent, sodium cyanide or potassium cyanide is used as catalyst, and benzaldehyde is generated by bimolecular condensation reaction. [0007] [0008] "Journal of Hubei University for Nationalities (Natural Science Edition)" Vol. ...

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Problems solved by technology

[0008] "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

[0009] 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

[0010] 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

[0014] As we all know, methanol has the disadvantages of toxicity, flammability, explosion, and volatility.