Method for preparing 2,3,5-trimethylbenzoquinone by using ionic liquid carrying catalyst

Abstract

The invention relates to a method of preparing 2, 3, 5-trimethyl benzoquinone through ionic liquid-supported catalyst, which uses 2, 3, 6-trimethylphenol raw material, uses ionic liquid-supported acetylacetone metal as catalyst and uses alcohol solvent containing three to ten carbon atoms. At the reaction temperature from -30 DEG C to 150 DEG C, molecular oxygen or oxygen-enriched gas is used to oxidize 2, 3, 6-trimethylphenol to form 2, 3, 5-trimethyl benzoquinone. The catalyst has the following general formula of [ace-Cnmim][X]-M, wherein ace represents the category of acetylacetone; mim represents the category of imidazole; X represents the category of anion; M represents metal. The catalyst used in the invention has very good thermal stability, good solubility, little corrosion, simple recycling and repeated utilization capability.

Description

Method for preparing 2,3,5-trimethylbenzoquinone with ionic liquid supported catalyst technical field The invention relates to a method for preparing 2,3,5-trimethylbenzoquinone (TMBQ) by oxidation of 2,3,6-trimethylphenol (TMP) by using metal acetylacetonate supported by ionic liquid as a catalyst. Background technique 2,3,5-Trimethylbenzoquinone is an important intermediate for the preparation of vitamin E. There have been many known methods for the oxidation of trimethylphenol to 2,3,5-trimethylbenzoquinone for a long time. In US3956346, the oxidation of trimethylphenol in the presence of sulfuric acid is described using natural manganese dioxide as oxidizing agent. This method will generate a large amount of corresponding reduced metal sludge-like waste, and waste acid will be generated, which will cause great environmental problems, and it will cost a lot to regenerate or treat the waste. In EP0659727, a manganese tetraaza[14]annulene or cadmium complex is used a...

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Problems solved by technology

This method will produce a large amount of corresponding reduced metal sludge-like waste, and waste acid will be generated, causing great environmental problems, and it will cost a lot to regenerate or treat the waste.

In EP0659727, manganese tetraaza[14]annulene or cadmium complexes are used as catalysts, but the catalyst complexes will be destroyed in the oxidation reaction, thereby generating metal waste and increasing production costs

At the same time, the reaction must be carried out in an organic solvent, and the use of a large amount of organic solvent will also cause certain environmental problems.

In US2002 / 0143198, an oxidation scheme using a transition metal salt of aluminosilicate as a catalyst is announced, but its yield varies from 1% to 80%, which is generally lower than known methods, which is not conducive to industrialization

And use acetonitrile and other toxic organic solvents in the reaction, which will cause harm to the environment

In CN1436877, a method for preparing trimethylhydroquinone by paired electrolysis of trimethylphenol is disclosed. The defect of this method is that the concentration of trimethylhydroquinone obtained is too low, a large amount of electrolyte must be used, and the space-time efficiency is low. , and the treatment of electrolytic waste requires high cost

In US3796732, an oxidation scheme using copper chloride as a catalyst is described, which is carried out in a homogeneous phase in the presence of an inert solvent such as DMF. Competitive Advantage

In EP0127888, the method that trimethylphenol is oxidized to trimethylbenzoquinone in the presence of Li(CuCl3) has been announced. Although this method has a higher yield, it must use a large excess of lithium chloride. In the known method, the price of lithium chloride is very expensive, which is very unfavorable for industrial application

In DE19949795, a method for oxidation in a binary catalytic system composed of copper halide and transition metal halide is described. Although this scheme has a high yield, a large amount of organic solvent must be used in order to reduce by-products, so that space-time rate drop

Moreover, the alcohol solvent used will also be oxidized under this condition, which makes it difficult to recycle.

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