A kind of method that takes caprolactam as raw material to synthesize hexamethylene diamine

Abstract

The invention discloses a method for synthesizing hexamethylenediamine using caprolactam as a raw material, comprising the following steps: 1) after mixing caprolactam, alkali and water, heating and refluxing to obtain 6-aminocaproate; 6-aminocaproic acid salt introduces amino protecting group to protect terminal amino group, then adds acid and neutralizes to generate aminocaproic acid with amino protecting group; 3) after drying the product obtained in step 2), add dehydration catalyst for amide And heating reaction in the presence of ammonia source converts carboxylic acid group into cyano group to obtain product nitrile; 4) The product nitrile obtained in step 3) is extracted and purified, catalytically hydrogenated to generate corresponding amine, and then the protective group is removed to obtain target product.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for synthesizing hexamethylenediamine by using caprolactam as a raw material. Background technique [0002] Hexamethylenediamine is an important chemical raw material, which is often used to synthesize important industrial products such as nylon 66, nylon 610, HDI, etc. However, there is no production facility for hexamethylenediamine synthetic raw material adiponitrile in my country, and it is completely dependent on imports. , the development of new synthetic methods is crucial. At present, there are not many methods for synthesizing hexamethylene diamine, and the industry is mainly the catalytic hydrogenation of adiponitrile, and the synthesis method of the raw material adiponitrile is butadiene and acrylonitrile method. The production of adiponitrile by the butadiene method is further divided into the chlorinated cyanation method of butadiene a...

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Problems solved by technology

[0003] There are very few reports on the synthesis of hexamethylenediamine from caprolactam. It was first reported in US2234566 and US2181140 patents that caprolactam reacted with ammonia gas under a dehydration catalyst and severe temperature to obtain 6-aminocapronitrile, and unreacted caprolactam was separated by distillation. Aminocapronitrile is synthesized into hexamethylenediamine by catalytic hydrogenation of aminocapronitrile subsequently on nickel or cobalt catalyst, but the yield of hexamethylenediamine is not disclosed in the patent; The method of caprolactam synthesis 6-aminocapronitrile reported in patent CN107739318A, CN107602416A and patent US2234566 The method of reporting is almost the same

Among them, the gas phase method reported by patent CN107602416A uses caprolactam to prepare 6-aminocapronitrile. The reaction temperature is about 350 ° C, and the contact time between caprolactam and ammonia is extremely short within 1 second, which is difficult to control; while the liquid phase method reported by patent CN107739318A Although the reaction temperature in the method of synthesizing 6-aminocapronitrile with caprolactam as a raw material is mild at about 280°C, its yield is not high, and its yield is about 50% analyzed from examples

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