Preparation method for amination synthesis of N-methylpiperidine from 1,5-pentanediol

Abstract

The invention belongs to the technical field of preparation of heterocyclic compounds, and specifically relates to a preparation method for amination synthesis of N-methylpiperidine from 1,5-pentanediol. The method comprises the following steps: with 1,5-pentanediol and monomethylamine as raw materials, carrying out an amination reaction in a tubular reactor filled with two upper-and-lower layersof a catalyst so as to obtain a crude product, and carrying out refining so as to obtain the N-methylpiperidine. The preparation method provided by the invention uses equipment with small size, is simple for industrial amplification, has relatively low cost and small technical investment, and can reach a product purity of 98.0% or above.

Description

technical field [0001] The invention belongs to the technical field of preparation of heterocyclic compounds, and in particular relates to a preparation method for synthesizing N-methylpiperidine through amination of 1,5-pentanediol. Background technique [0002] N-methylpiperidine, English name N-Methyl piperidine, alias N-methylhexahydropyridine, molecular formula C 6 h 13 N, its chemical structure is as follows: ; Colorless liquid; molecular weight 99.2, flash point 3 ° C, boiling point 106 ~ 107 ° C; miscible with water, miscible with alcohol, ether and so on. N-Methylpiperidine vapor forms an explosive mixture with air, which can cause combustion and explosion when exposed to open flames and high heat; it can react strongly with oxidants; its vapor is heavier than air, and can spread to a relatively far place at a lower place, and it will explode when exposed to open flames Lead to backfire. [0003] N-methylpiperidine is an important fine chemical intermediate, ma...

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Problems solved by technology

[0004] 1) Use methyl iodide and piperidine as raw materials to obtain the product N-methylpiperidine. Although this method has a relatively high yield, it will produce a large amount of halide ammonium salt, which is easy to cause corrosion to the equipment

And the methyl iodide price that this method uses is higher, causes production cost height, is not suitable for industrial production

[0005] 2) In the case of an iridium complex as a homogeneous catalyst, piperidine and formaldehyde are used as raw materials to synthesize N-methylpiperidine. The reaction conditions are mild and the product yield is good, but the recycling of the catalyst is a big problem. problems, and thus higher cost

[0006] 3) Under the action of copper-based catalyst, the product N-methylpiperidine was obtained by using 1,5-pentanediol and methylamine as raw materials. Although this method is relatively green, the yield is not high (only 62-82 %), and there will be more side effects

Moreover, this reaction needs to be carried out under high pressure, and the pressure reaches 20MPa, which requires high reaction equipment, which will increase the cost of industrial production and also pose a great hidden danger to safe production.

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