Method for generating lactam by acetylpropionic acid conversion

Abstract

The invention discloses a method for generating lactam by acetylpropionic acid conversion. The method comprises the steps as follows: taking dimethyl sulfoxide as a solvent and cheap and clean methanoic acid as a hydrogen source under the protection of inert gas, and producing a reductive amination reaction of acetylpropionic acid generated by direct biomass conversion and primary amine to prepare lactam. Compared with the conventional method, no metal catalyst is used, the reaction condition is more moderate, the operation is simple, the process is green and environment-friendly, the environmental pollution is reduced, the product yield is high, and the industrial production cost is low.

Description

technical field [0001] The invention belongs to the technical field of lactam preparation, and in particular relates to a method for producing lactam from levulinic acid without the participation of a catalyst. Background technique [0002] Levulinic acid is a class of compounds that can be directly obtained from carbohydrates, cellulose and other biomass by one-step high-temperature acid hydrolysis. It has important applications in chemical industry, dyestuffs, and pharmaceuticals. It is called a new generation of chemical platform substances. Caprolactam is a very important intermediate, widely used in pharmaceutical, medical and other industries. [0003] In the process of producing levulinic acid by high-temperature acidolysis of biomass, an equivalent amount of formic acid will be produced at the same time. If the formic acid produced in this part can be efficiently used as a hydrogen source to reduce levulinic acid and make it through reductive amination The method of...

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Problems solved by technology

In the current literature, there are not many reports on the method of obtaining caprolactam from levulinic acid in one step with formic acid as a hydrogen donor. 2 ] 2 As a catalyst, the amount of the catalyst is 0.5mmol%, and a phosphine ligand is added, and the reaction is carried out at 80-120°C for 12 hours, and caprolactam can be obtained directly. This method uses a metal catalyst and adds an unstable phosphine ligand. Before reductive amination, it is necessary to use a catalyst to convert formic acid into hydrogen, which has high requirements on the reactor, has certain risks, and the uncontrollability of the reaction is high; (2) Xiao Jianliang's research group reported in 2013 that using iridium-imine cyclometal Compound compound is used as catalyst, the amount of catalyst is 0.05mmol%, water is used as solvent, and caprolactam can be obtained directly under the condition of 80 ℃ for 2-12 hours, and the yield is 72%-96%. This method is a kind of It is a very good method to achieve reductive amination through standard transfer hydrogenation. The substrate has a wide range of applications. The disadvantage is that it uses a metal catalyst and it is difficult to recover in practice; (3) Fan Kangnian’s research group reported in 2011 that the following Gold-zirconia is used as a heterogeneous catalyst, the amount of catalyst is 0.05mmol%, and it is reacted at 130°C for 12 to 24 hours to obtain caprolactam, and the yield is >80%. The yield of this method is relatively high, and an inorganic catalyst is used. It is beneficial to the recovery and utilization of the catalyst, but the scope of application of the substrate of this method is limited, and in the process of obtaining caprolactam through reduction, a catalyst is first required to decompose formic acid into hydrogen, and there are certain requirements for the reaction vessel in production; (4) US Patent A method for reductive amination of levulinic acid is disclosed in US6841520, which uses aryl cyanide as the amine source, hydrogen as the hydrogen source, and adds a heterogeneous catalyst. Under the condition of 7.6MPa, the corresponding lactam is generated. This patent was published earlier, but the temperature required for the reaction is high, the pressure is high, and the yield is very low, so it has little application value in actual production

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