Preparation method of 1-mehtyl-2-ethylimidazole

Abstract

The present invention relates to a kind of preparation method of 1-methyl-2-ethylimidazole, especially relate to a kind of use pure methylamine, ammonia gas, pure propionaldehyde and glyoxal aqueous solution as raw material, adopt gas-liquid phase method, One-step reaction to synthesize 1-methyl-2-ethylimidazole. Add glyoxal aqueous solution to the gas-liquid phase reaction kettle; under temperature control and micro-negative pressure, first pass pure propionaldehyde, and then pass through ammonia and pure methylamine at the same time; after adding, continue to control temperature and micro-negative pressure After the reaction was completed, the water was evaporated, cooled, crystallized, filtered, and dried to obtain the product. The method adopts a one-step method, and the ammonia water or the ammonia salt solution and the acetaldehyde solution are changed into ammonia gas and pure acetaldehyde to participate in the reaction, so that the production cost is greatly reduced.

Description

1. Technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for synthesizing 1-methyl-2-ethylimidazole by using methylamine, ammonia gas, pure propionaldehyde and glyoxal aqueous solution as raw materials. 2. Background technology [0002] Imidazole compounds are a class of nitrogen-containing five-membered heterocyclic compounds, which are widely used in many fields such as composite materials, medicine, dyes, curing agents, and metal anticorrosion. 1-methyl-2-ethylimidazole is one of the important intermediates of imidazoles, and its structural formula is: [0003] [0004] Its traditional synthesis method is to adopt two-step method to prepare, first use propionaldehyde aqueous solution, ammonia water and glyoxal aqueous solution to condense to obtain 2-ethylimidazole, then further react with dimethyl sulfate methylation to obtain 1-methyl- 2-ethylimidazole. The first step of the above-mentioned p...

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Problems solved by technology

The first step of the above-mentioned preparation process has the problem of high energy consumption for water separation: before the reaction, water must be added to the raw materials to make an unsaturated solution, so that 2-ethylimidazole can be synthesized by the liquid phase method in a low-cost normal-pressure reactor , after the reaction, the water must be evaporated to separate

Moreover, this method needs two steps to complete, the yield is relatively low, there are many by-products, and it is difficult to separate and purify.

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