Catalyst for synthesis of vanillin and preparation method of catalyst

Abstract

The invention provides a catalyst for synthesis of vanillin and preparation method of the catalyst. The catalyst is a coordination compound and has structural expression as described in the specification. The preparation method of the catalyst comprises the following steps: 1) dropwise adding butyl lithium into alkylpyridine, then adding trimethyltin chloride, and conducting reacting to obtain a product 1; 2) mixing the product 1, a 2-bromo-4-sulfonyl pyridine compound and a catalyst, and conducting reacting to obtain a product 2; and 3) mixing and stirring a ferrous compound and the product 2 in a solvent to prepare the catalyst. By synthesizing the iron ligand catalyst and applying the iron ligand catalyst to a glyoxylic acid-process synthesis method for vanillin, the yield of an oxidation reaction and a condensation reaction can be greatly improved, so the production efficiency and yield of vanillin are improved; and the method has the advantages of simple process and no extra introduction of redundant impurities, and is suitable for wide industrial application.

Description

technical field [0001] The invention relates to a preparation method, in particular to a vanillin synthesis catalyst and a preparation method thereof, belonging to the technical field of catalysts. Background technique [0002] Vanillin, commonly known as vanillin, chemically named 3-methoxy-4-hydroxybenzaldehyde, has the unique aroma of vanilla, usually white or light yellow crystalline powder, and is the largest synthetic fragrance in the world. The global annual production capacity is about 30,000 tons. At present, more than 80% of vanillin is synthesized by glyoxylic acid route, which includes the steps of glyoxylic acid condensation, mandelic acid oxidation and acidification decarboxylation. The glyoxylic acid method has the following problems: 1. The selectivity of the condensation reaction is low, and a large number of ortho by-products and di-condensation by-products are generated, and the condensation by-products are difficult to recover, resulting in high COD of w...

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Problems solved by technology

The glyoxylic acid method has the following problems: 1. The selectivity of the condensation reaction is low, and a large number of ortho by-products and di-condensation by-products are generated, and the condensation by-products are difficult to recover, resulting in high COD of wastewater; 2. The mainstream oxidation process is still Using copper oxide as an oxidant, although it has a high yield, the reaction rate is slow, and a large amount of copper oxide needs to be added to participate in the reaction, and a large amount of cuprous oxide is produced by-product, which brings great harm to the filtration and regeneration of the oxidant in the later stage. many inconveniences

This process route is simple, directly oxidize after recovering guaiacol under acidic conditions, which not only reduces the consumption of lye, but also can obtain vanillin in one step of oxidation, but the biggest disadvantage is that vanillin is unstable Further reaction under the conditions, resulting in lower yield of vanillin

Chinese patent CN102260150A discloses a high-efficiency oxidation method for mandelic acid aqueous solution. A self-priming reactor is used to feed oxygen, which effectively reduces the reaction time and realizes catalyst recycling. However, it is difficult to control the reaction end point and prone to insufficient oxidation or excessive oxidation. The problem

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