Method for preparing N-methyl-2-piperidone

Abstract

The invention provides a method for preparing N-methyl-2-piperidone, which comprises the following steps of: mixing delta-valerolactone and methylamine, enabling the delta-valerolactone and methylamine to react at preset temperature and pressure, forming an intermediate product N-methyl amide by ring opening of the delta-valerolactone and methylamine, and dehydrating and cyclizing to form a mixed solution containing N-methyl-2-piperidone; and cooling the mixed solution to room temperature, and then carrying out reduced pressure distillation to obtain a fraction product N-methyl-2-piperidone with the yield of more than 90%. The raw materials are simple and easy to obtain, the reaction is easy to operate, and the application prospect is wide.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical preparation, and particularly relates to a method for preparing N-methyl-2-piperidone. Background Art

[0002] N-methyl-2-piperidone is an important fine chemical intermediate. Due to its unique chemical properties, N-methyl-2-piperidone plays an important role in a variety of industrial processes and has a wide range of applications in multiple fields.

[0003] First of all, N-methyl-2-piperidone can be used as a solvent in organic synthesis, especially in the synthesis of special engineering plastics such as polyarylene sulfide. This plastic has excellent properties and is widely used in high-tech fields. It can also be used as a raw material to synthesize bioactive substances such as specific antibodies, which have important application values in the fields of medicine and biotechnology.

[0004] Secondly, in organic synthesis reactions, N-methyl-2-piperidone often appears as a key intermediate, participates in the synthesis routes of various complex compounds, and can also be used in drug synthesis. Although N-methyl-2-piperidone itself may not be directly used in drugs, it can be used as a key raw material for synthesizing certain drugs or drug intermediates. Some studies have shown that compounds containing the N-methyl-2-piperidone structure may have specific biological activities, such as anti-tumor and antibacterial activities, which provide new directions for medical research. In addition, in the process of pesticide manufacturing, N-methyl-2-piperidone may be used as a solvent or extractant to help extract and purify pesticide active ingredients. In the coating and dye industries, it may also be used as a solvent or dispersant to improve the quality and performance of products.

[0005] The existing synthesis methods of N-methyl-2-piperidone mainly include: 1. Cyclization of 5-chlorovaleronitrile and methylamine to generate it, with a yield of 61.2%; 2. Using benzene as a solvent, refluxing with excessive dimethyl sulfate and 2-piperidone for 16 hours, with a yield of 70%; 3. Using valerolactam as a raw material, iodomethane as a methylation reagent, adding a phase transfer catalyst, and under the condition of strong base (NaH), with a yield of 93%.

[0006] Each of the above three methods has its own disadvantages. Method 1 has a low yield, Method 2 has a long reaction time, and Method 3 has expensive raw materials and harsh operating conditions for sodium hydride. Summary of the Invention

[0007] In view of the technical defects existing in the existing preparation methods of N-methyl-2-piperidone, the present invention proposes a method for preparing N-methyl-2-piperidone.

[0008] The present invention protects a method for preparing N-methyl-2-piperidone, which includes the following steps:

[0009] Step 1: Mix δ-valerolactone with methylamine and react under a predetermined temperature and a predetermined pressure to obtain a mixed solution.

[0010] Step 2: Cool the mixed solution to room temperature to obtain an aqueous solution containing N-methyl-2-piperidone.

[0011] Step 3: Subject the aqueous solution containing N-methyl-2-piperidone to vacuum distillation to obtain N-methyl-2-piperidone.

[0012] In the present invention, δ-valerolactone is mixed with methylamine, and the two will react under a predetermined temperature and pressure. δ-Valerolactone and methylamine undergo ring-opening to form an intermediate product, N-methylamide, which then undergoes dehydration cyclization to form a mixed solution containing N-methyl-2-piperidone. The mixed solution is cooled to room temperature and then subjected to vacuum distillation to obtain the fraction product N-methyl-2-piperidone, with a yield of over 90%.

[0013] Further, in Step 1, the mass ratio of δ-valerolactone to methylamine is 1:(0.7 - 2).

[0014] Further, the methylamine is an aqueous solution of methylamine with a mass concentration of 39 - 40%.

[0015] Further, in Step 1, the reaction temperature is 250°C - 330°C, the reaction pressure is 4 - 12 MPa, and the reaction time is 4 - 12 hours.

[0016] Further, in Step 3, the vacuum distillation temperature is 70 - 75°C and the pressure is 150 - 280 Pa.

[0017] The present invention also protects an N-methyl-2-piperidone prepared by the above method.

[0018] The method for preparing N-methyl-2-piperidone provided by the present invention has the following advantages:

[0019] 1. The raw materials are simple and easily available, the reaction is easy to operate, and it has a broad application prospect;

[0020] 2. The raw material conversion rate is high and the product yield is high.

[0021] The additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0023] Figure 1 This is the gas chromatogram of N-methyl-2-piperidone obtained in Example 1 of the present invention. Specific Embodiments

[0024] The present invention will be described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0025] Example 1

[0026] 50 g of δ-valerolactone and 43 g of 40% by mass aqueous methylamine solution were added to a 0.5 L high-pressure reactor, heated to 290 °C, and stirred for reaction for 6 hours. After the reaction, it was cooled to room temperature to obtain an aqueous solution containing N-methyl-2-piperidone. Sampling was carried out, and gas chromatography was measured. The conversion rate of δ-valerolactone was 100%, and the selectivity of N-methyl-2-piperidone was as high as 99.3%.

[0027] Under the conditions of reduced pressure distillation at 73 °C and 250 Pa, the distillate was 54.2 g of N-methyl-2-piperidone, and the yield was 96%.

[0028] The gas chromatogram of the product prepared in this example is shown in Figure 1 , and by comparing with the chromatogram of the standard sample, it can be known that this product is N-methyl-2-piperidone.

[0029] Example 2

[0030] 50 g of δ-valerolactone and 43 g of 40% by mass aqueous methylamine solution were added to a 0.5 L high-pressure reactor, heated to 270 °C, and stirred for reaction for 6 hours. After the reaction, it was cooled to room temperature to obtain a mixture containing N-methyl-2-piperidone. Sampling was carried out, and gas chromatography was measured. The conversion rate of δ-valerolactone was 99.2%, and the selectivity of N-methyl-2-piperidone was 93.2%.

[0031] Under the conditions of reduced pressure distillation at 75 °C and 250 Pa, the distillate was 51.4 g of the product N-methyl-2-piperidone, and the yield was 91%.

[0032] Example 3

[0033] 51.2 g of δ-valerolactone and 43 g of 40% by mass aqueous methylamine solution were added to a 0.5 L high-pressure reactor, heated to 250 °C, and stirred for reaction for 6 hours. After the reaction, it was cooled to room temperature to obtain an aqueous solution containing N-methyl-2-piperidone. Sampling was carried out, and gas chromatography was measured. The conversion rate of δ-valerolactone was 97%, and the selectivity of N-methyl-2-piperidone was as high as 90%.

[0034] Under reduced pressure distillation at 70 °C and 200 Pa, the distillate was 26.0 g of N-methyl-2-piperidone with a yield of 90%.

[0035] Example 4

[0036] 50 g of δ-valerolactone and 100 g of 40% by mass aqueous methylamine solution were added to a 0.5 L high-pressure reactor, heated to 290 °C, and stirred for reaction for 6 hours. After the reaction, it was cooled to room temperature to obtain an aqueous solution containing N-methyl-2-piperidone. Sampling was carried out, and gas chromatography was measured. The conversion rate of δ-valerolactone was 100%, and the selectivity of N-methyl-2-piperidone was as high as 99.5%.

[0037] Under reduced pressure distillation at 73 °C and 250 Pa, the distillate was 55.9 g of N-methyl-2-piperidone with a yield of 99%.

[0038] Example 5

[0039] 50 g of δ-valerolactone and 35 g of 40% by mass aqueous methylamine solution were added to a 0.5 L high-pressure reactor, heated to 290 °C, and stirred for reaction for 6 hours. After the reaction, it was cooled to room temperature to obtain an aqueous solution containing N-methyl-2-piperidone. Sampling was carried out, and gas chromatography was measured. The conversion rate of δ-valerolactone was 95%, and the selectivity of N-methyl-2-piperidone was as high as 96%.

[0040] Under reduced pressure distillation at 73 °C and 250 Pa, the distillate was 46.7 g of N-methyl-2-piperidone with a yield of 93%.

[0041] Judging from the gas phase test results of Examples 1-5, the method provided by the present invention can successfully prepare N-methyl-2-piperidone; at the same time, the raw materials for preparation are relatively simple and easy to obtain. The conversion rate of the raw material δ-valerolactone is about 95%, and the yield of the product N-methyl-2-piperidone exceeds 90%, showing broad application prospects.

[0042] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0043] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing N-methyl-2-piperidone, characterized in that: The steps include: Step 1, mixing δ-valerolactone and methylamine, and reacting them at a predetermined temperature and a predetermined pressure to obtain a mixed solution; Step 2, cooling the mixed solution to room temperature to obtain an aqueous solution containing N-methyl-2-piperidone; Step 3, distilling the aqueous solution containing N-methyl-2-piperidone under reduced pressure to obtain N-methyl-2-piperidone.

2. The method according to claim 1, characterized in that In step 1, the mass ratio of the delta-valerolactone to the methylamine is 1:(0.7-2).

3. The method according to claim 2, characterized in that The methylamine is a methylamine aqueous solution with a mass concentration of 39-40%.

4. The method according to claim 1, characterized in that: The reaction temperature in step 1 is 250° C. to 330° C., the reaction pressure is 4 to 12 MPa, and the reaction time is 4 to 12 hours.

5. The method according to claim 1, characterized in that The reduced pressure distillation temperature in step 3 is 70-75° C. and the pressure is 150-280 Pa.

6. N-methyl-2-piperidone, characterized in that The method according to any one of claims 1 to 5 is used to prepare the present invention.

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