Continuous preparation method of 2-pentylidene cyclopentanone

Abstract

The invention belongs to the technical field of organic synthesis, and particularly discloses a continuous preparation method of 2-pentylidene cyclopentanone, which comprises the following steps: mixing n-valeraldehyde and cyclopentanone according to a certain proportion, respectively pumping a strong alkaline aqueous solution and the mixed raw materials into a mixing section through a feeding pump, uniformly mixing, feeding into a reaction section, and reacting for 2-4 hours at the temperature of 20-30 DEG C to obtain 2-pentylidene cyclopentanone. 2-pentylidene cyclopentanone is prepared by heating and staying reaction, and the reacted material is cooled by a cooling section and then enters a receiving tank. The device is formed by connecting a feeding pump, a mixing section, a reaction section, a cooling section and a receiving tank in series, wherein a back pressure valve is arranged on a pipeline between the cooling section and the receiving tank; the mixing section is a heart-shaped mixer; the reaction section is made of a plurality of reaction modules, and materials can be fully mixed in the reaction modules due to the special internal structures of the reaction modules. The method has the advantages of simple process, cheap and easily available catalyst, high reaction selectivity, realization of continuous production of 2-pentylidene cyclopentanone, and high industrial application value.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and relates to the preparation of 2-pentylidenecyclopentanone, an intermediate used for synthesizing methyl dihydrojasmonate, a fragrance, and specifically relates to a continuous preparation method of 2-pentylidenecyclopentanone. Background Art

[0002] 2-Pentylidenecyclopentanone, English name 2-pentylidenecyclopentan-1-one, is a colorless or light yellow oily liquid, mainly used in the synthesis of fragrance methyl dihydrojasmonate.

[0003] Literature: Chen Zhaogang, Zhang Qianghua, Lin Xiang. Synthesis of methyl dihydrojasmonate [J]. Flavors, Fragrances and Cosmetics, 2010 (1): 6-8 reported that n-valeraldehyde and cyclopentanone were used as raw materials, and the intermediate 2-(1-hydroxypentyl) cyclopentanone was first reacted at low temperature in a 2% sodium hydroxide aqueous solution. Then, the intermediate 2-(1-hydroxypentyl) was dehydrated under iodine catalysis to obtain the product 2-pentylidene cyclopentanone. This method is cumbersome, the total yield of the two-step reaction is only 71%, and the dehydration reaction also needs to be carried out in xylene solvent, which is not suitable for industrial production. Patent CN102001925A reported that n-valeraldehyde and cyclopentanone were used as raw materials, toluene was used as solvent, and homemade potassium fluoride / aluminum oxide was used as catalyst. The product 2-pentylidene cyclopentanone was obtained by one-step reaction. The yield of this method can reach 88%, but this method needs to prepare potassium fluoride / aluminum oxide as catalyst in advance, the steps are cumbersome, and the catalyst cost is high. The environmental pollution is serious, which is not conducive to industrial production. Literature: Nie Wenyan. Study on the Synthesis Process Conditions of Methyl Dihydrojasmonate [J]. Sichuan Chemical Industry, 2012 (5): 5-8 reported that n-valeraldehyde and cyclopentanone were added dropwise to 1% sodium hydroxide solution at a molar ratio of 1:1.5, and the reaction was carried out at 80°C. The product 2-pentylidenecyclopentanone was obtained in one step. The yield of this method can reach 90%. This method overcomes the problem of complex process and has a high yield. However, it still uses intermittent reactor reaction and fails to improve the reaction to be continuous, which limits the industrial application prospects of this method. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a continuous preparation method of 2-pentylidenecyclopentanone. The present invention uses n-valeraldehyde and cyclopentanone as raw materials and a strong alkaline solution as a catalyst to continuously react in a special reaction module to obtain 2-pentylidenecyclopentanone. The present invention has a simple process, a cheap and easily available catalyst, high reaction selectivity, and can realize continuous production of 2-pentylidenecyclopentanone, and has high industrial application value.

[0005] The present invention is achieved through the following technical solutions:

[0006] A continuous preparation method of 2-pentylidenecyclopentanone comprises the following steps: n-valeraldehyde and cyclopentanone are mixed in a certain proportion, a strongly alkaline aqueous solution and the mixed raw materials are respectively pumped into a mixing section through a feed pump to mix evenly, and then enter a reaction section, and the temperature is raised to stay for reaction to prepare 2-pentylidenecyclopentanone, and the materials after the reaction are cooled in a cooling section and then enter a receiving tank, and the product is qualitatively and quantitatively analyzed by gas chromatography.

[0007] A further improvement of the present invention is:

[0008] The mixing section is a heart-shaped mixer.

[0009] Furthermore, the reaction section is made of multiple reaction modules and an oil bath jacket coated on the outer wall of the reaction module. The reaction module is composed of a shell and a coil placed in the shell. The coil is a stainless steel tube with a diameter of 10 mm, and a mesh filler is provided in the stainless steel tube. The reaction modules in the reaction section can be one or two or more. When there are multiple reaction modules, the reaction modules are connected in series through pipelines.

[0010] Furthermore, the cooling section is made of a stainless steel pipe with a length of 6m and an inner diameter of 10mm, and a cooling liquid jacket is provided on the outside.

[0011] Furthermore, a back pressure valve is provided on the pipeline between the cooling section and the receiving tank.

[0012] Furthermore, the strong alkaline solution is one or a mixture of two or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a cesium hydroxide aqueous solution.

[0013] Furthermore, the mass concentration of the strong alkaline aqueous solution is 1% to 10%.

[0014] Furthermore, the mass ratio of the mixed raw material to the strong alkaline aqueous solution is 1:1-5.

[0015] Furthermore, the molar ratio of n-valeraldehyde to cyclopentanone is 1:1-3.

[0016] Furthermore, the temperature of the residence reaction is 60-100° C., the pressure is 0.1-0.2 MPa, and the residence time is 5-60 min.

[0017] The beneficial effects of the present invention are:

[0018] The method of the invention has simple process, cheap and readily available catalyst, fast reaction speed, high reaction conversion rate, high reaction selectivity, can realize continuous production of 2-pentylidenecyclopentanone, and has high industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1Schematic diagram of the reaction device of the present invention.

[0020] Among them, 1-mixing section, 2-reaction section, 3-cooling section, 4-back pressure valve, 5-thermal oil inlet, 6-thermal oil outlet, 7-reaction module, 8-cooling liquid inlet, 9-cooling liquid outlet.

[0021] Figure 2 This is a schematic diagram of the internal structure of the reaction module of the present invention.

[0022] Among them, 71 is the outer wall of the reaction module, 72 is the stainless steel tube with an inner diameter of 10 mm inside the reaction module, and 73 is the mesh filler inside the stainless steel tube. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific embodiments.

[0024] Example 1

[0025] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 0.5% sodium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.5 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 5:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 15 minutes. The temperature of the reaction section was controlled at 95°C by an oil bath, the cooling temperature was controlled at 25°C by a coolant, and the reaction pressure was controlled at 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography. The reaction results are shown in Table 1

[0026] Example 2

[0027] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 1% sodium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.2 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 4:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 10 minutes. The temperature of the reaction section was controlled at 90°C by an oil bath, the cooling temperature was controlled at 25°C by a coolant, and the reaction pressure was controlled at 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography. The reaction results are shown in Table 1

[0028] Example 3

[0029] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 1% sodium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.3 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 5:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 15 minutes. The temperature of the reaction section was controlled at 90°C by an oil bath, the cooling temperature was controlled at 25°C by a coolant, and the reaction pressure was controlled at 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography. The reaction results are shown in Table 1

[0030] Example 4

[0031] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 1% sodium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.3 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 4:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 10 minutes. The temperature of the reaction section was controlled to 95°C by an oil bath, the cooling temperature was controlled to 25°C by a coolant, and the reaction pressure was controlled to 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography, and the reaction results are shown in Table 1.

[0032] Example 5

[0033] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 2% sodium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.5 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 3:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 20 minutes. The temperature of the reaction section was controlled to 80°C by an oil bath, the cooling temperature was controlled to 25°C by a coolant, and the reaction pressure was controlled to 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography, and the reaction results are shown in Table 1.

[0034] Example 6

[0035] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 1% potassium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.3 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 3:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 15 minutes. The temperature of the reaction section was controlled at 90°C by an oil bath, the cooling temperature was controlled at 25°C by a coolant, and the reaction pressure was controlled at 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography, and the reaction results are shown in Table 1.

[0036] Example 7

[0037] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 2% potassium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.4 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 2:1. After the two groups of mixed materials were mixed by a core-shaped mixer, the residence time in the reaction section was 20 minutes. The temperature of the reaction section was controlled to 85°C by an oil bath, the cooling temperature was controlled to 25°C by a coolant, and the reaction pressure was controlled to 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography, and the reaction results are shown in Table 1.

[0038] Example 8

[0039] The synthesis experiment of 2-pentylidenecyclopentanone was carried out in a reactor made of multiple reaction modules, and 1% cesium hydroxide aqueous solution was fed by feed pump 1. A mixture of n-valeraldehyde and cyclopentanone with a molar ratio of 1:1.4 was fed by feed pump 2, and the feed ratio of feed pump 1 and feed pump 2 was 3:1. After the two groups of mixed materials were mixed by a heart-shaped mixer, the residence time in the reaction section was 20 minutes. The temperature of the reaction section was controlled to 85°C by an oil bath, the cooling temperature was controlled to 25°C by a coolant, and the reaction pressure was controlled to 0.15MPa by a back pressure valve. The reaction liquid collected by the receiving tank was used for qualitative and quantitative analysis of the product by gas chromatography, and the reaction results are shown in Table 1.

[0040] Table 1 Reaction results of Examples 1-8

[0041]

[0042] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A continuous preparation method of 2-pentylidenecyclopentanone, characterized in that: The method comprises the following steps: mixing n-valeraldehyde and cyclopentanone in a certain proportion, pumping a strong alkaline aqueous solution and the mixed raw materials into a mixing section through a feed pump respectively, mixing them evenly, entering a reaction section, heating and stopping the reaction to prepare 2-pentylidenecyclopentanone, cooling the reacted materials in a cooling section and then entering a receiving tank, and performing qualitative and quantitative analysis of the products by using gas chromatography.

2. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The mixing section is a heart-shaped mixer.

3. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The reaction section is provided with a reaction module and an oil bath jacket covering the outside of the reaction module. The reaction module is composed of a shell and a coil placed in the shell. The coil is a stainless steel tube with a diameter of 10 mm. A mesh filler is arranged in the stainless steel tube. The reaction modules in the reaction section can be one or two or more. When there are multiple reaction modules, the reaction modules are connected in series through pipelines.

4. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The cooling section is made of a stainless steel pipe with a length of 6m and an inner diameter of 10mm, and a cooling liquid jacket is arranged on the outside thereof.

5. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: A back pressure valve is arranged on the pipeline between the cooling section and the receiving tank.

6. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The strong alkaline solution is one or a mixture of two or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a cesium hydroxide aqueous solution.

7. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1 or 6, characterized in that: The mass concentration of the strong alkaline aqueous solution is 1% to 10%.

8. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The mass ratio of the mixed raw material to the strong alkaline aqueous solution is 1:1-5.

9. A continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The molar ratio of n-valeraldehyde to cyclopentanone is 1:1-3.

10. The continuous preparation method of 2-pentylidenecyclopentanone according to claim 1, characterized in that: The temperature of the residence reaction is 60-100° C., the pressure is 0.1-0.2 MPa, and the residence time is 5-60 min.

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