Clean production process of propionyl chloride and application thereof

Abstract

The invention discloses a clean production process of propionyl chloride, which comprises the following steps: S1, mixing propionic acid with a catalyst, and then feeding together with thionyl chloride for reaction; s2, entering a curing tower for curing, and then entering a light component removal tower for removing by-product gas; and S3, feeding a material discharged from the bottom of the light component removal tower into a continuous rectifying tower, and extracting propionyl chloride from the tower top. According to the method, the content of thionyl chloride in propionyl chloride can be reduced, the purity of propionyl chloride is improved, and the yield of downstream products is increased. The purity of the obtained hydrogen chloride and sulfur dioxide is high, the result of mutual mixing of hydrogen chloride and sulfur dioxide is avoided, and the added value of byproducts is high. Solid waste does not need to be treated, the method is clean and environmentally friendly, propionyl chloride with the purity larger than 99%, hydrogen chloride with the purity larger than 99.5% and sulfur dioxide gas can be obtained, the product quality is high, and the added value is high.

Description

Technical Field

[0001] The invention relates to a clean production process of propionyl chloride and application thereof, and relates to C07D, and in particular to the field of heterocyclic compounds. Background Art

[0002] Propionyl chloride is an important synthetic intermediate of organic compounds, which can be used as a synthetic intermediate of medicine and pesticides, and has an important role in chemical synthesis. The synthetic methods of propionyl chloride include phosphorus trichloride method, phosgene method and thionyl chloride method. The phosphorus trichloride method generates propionyl chloride, which will generate phosphorous acid as a byproduct, causing environmental pollution. In addition, propionyl chloride and phosphorous acid are easy to form an azeotropic mixture, which is not easy to separate. The purity of the generated propionyl chloride is not high, and impurities will be introduced when applied to post-processing, affecting the product quality. The traditional thionyl chloride method produces propionyl chloride, and propionyl chloride and thionyl chloride are not easy to separate, and the byproducts hydrogen chloride and sulfur dioxide generated are absorbed as tail gas, which has low added value and low economic benefits. Therefore, it is very important to develop a production process that is environmentally friendly and clean, has high added value of byproducts, high purity of propionyl chloride, and high yield.

[0003] Chinese invention patent CN201410266505.2 discloses a synthesis process of 2-thiopheneacetyl chloride, using dichloromethane as a solvent, heating under the protection of nitrogen, keeping the system slightly boiling, and dripping thionyl chloride, which has a low boiling point, easy desolventizing, mild reaction conditions, small catalyst dosage, and simple process. However, the generated tail gas sulfur dioxide is removed with the solvent volatilization, the added value of sulfur dioxide is low, and the economic efficiency is not high. Chinese invention patent CN201811262293.5 discloses a synthesis method of 2-thiopheneacetyl chloride, thiophene in the presence of a catalyst, and hydroxyacetic acid ester by FC reaction to obtain 2-thiopheneacetic acid ester; then hydrolyzed in the presence of acid to obtain 2-thiopheneacetic acid; finally, under the catalysis of pyridine, thionyl chloride is chlorinated to obtain 2-thiopheneacetyl chloride, the raw materials are easy to obtain, and the operation is simple. However, two catalysts are required, and the production cost is high. Summary of the invention

[0004] In order to develop a production process that is environmentally friendly and clean, has high added value of by-products, high purity of propionyl chloride, and high yield, the first aspect of the present invention provides a clean production process for propionyl chloride, comprising the following steps:

[0005] S1 mixes propionic acid with a catalyst, and then feeds it together with thionyl chloride into a reactor;

[0006] After S2 reacts, it enters the maturation tower for maturation, and then enters the light removal tower to remove the by-product gas;

[0007] The bottom discharge of the S3 light removal tower enters a continuous distillation tower, propionyl chloride is taken out from the top of the tower, and propionic acid and the catalyst are taken out from the bottom of the tower and re-enter the reactor for reaction.

[0008] As a preferred embodiment, the temperature of the light-removal tower is 70-75°C, and light-removal is continuous.

[0009] As a preferred embodiment, the reactor and the maturation tower (a device with wire mesh fillers added inside to increase the contact area (similar to the packing section of a packed distillation tower)) will produce by-product gas, which is deeply cooled, compressed, and distilled to obtain pure by-product gas.

[0010] As a preferred embodiment, the deep cooling temperature is -20 to -25°C, the deep cooling is continuous, and the compressed gas pressure is 1-3 MPa.

[0011] As a preferred embodiment, the generated by-product gas and the added thionyl chloride need to pass through a washing tower before being used for treatment.

[0012] As a preferred embodiment, the molar ratio of propionic acid to thionyl chloride is 1:(0.5-0.8).

[0013] As a preferred embodiment, the molar ratio of propionic acid to thionyl chloride is 1:(0.6-0.8).

[0014] As a preferred embodiment, the molar ratio of propionic acid to thionyl chloride is 1:0.6.

[0015] The applicant found in the experiment that propionic acid and thionyl chloride react according to the molar ratio of 1: (0.5-0.8), and the purity of the propionyl chloride formed is greater than 99%. Propionyl chloride is used to produce downstream products, and the yield of downstream products is high and free of impurities. The possible reason is guessed to be: propionic acid and thionyl chloride adopt a molar ratio of 1: (0.5-0.8), which can make thionyl chloride fully react to the greatest extent while maintaining the appropriate yield of propionyl chloride. When the usage amount of thionyl chloride is too much, part of thionyl chloride does not react thoroughly, and the boiling points of thionyl chloride, intermediate product, and propionyl chloride are close and difficult to separate, resulting in a decrease in the purity of propionyl chloride, and the purity and yield of downstream products are all decreased. However, if the usage amount of thionyl chloride is lower than the preferred weight ratio, the reaction process will be slow, more propionic acid will be recovered, and the production energy consumption will increase.

[0016] As a preferred embodiment, the reactor comprises a primary reactor and a secondary reactor, and the feed ratio of thionyl chloride in the primary reactor and the secondary reactor is (1-3):1.

[0017] As a preferred embodiment, the reactor comprises a primary reactor and a secondary reactor, and the feed ratio of thionyl chloride in the primary reactor and the secondary reactor is (2-3):1.

[0018] As a preferred embodiment, the reactor comprises a primary reactor and a secondary reactor, and the feeding ratio of thionyl chloride in the primary reactor and the secondary reactor is 2:1.

[0019] As a preferred embodiment, the reaction temperature of the primary reactor is 30-45°C, and the reaction time is 0.5-1.5h.

[0020] As a preferred embodiment, the reaction temperature of the primary reactor is 35-40°C, and the reaction time is 0.9-1.1h.

[0021] As a preferred embodiment, the reaction temperature of the primary reactor is 38° C. and the reaction time is 1 h.

[0022] As a preferred embodiment, the reaction temperature of the secondary reactor is 40-65°C, and the reaction time is 0.5-1.5h.

[0023] As a preferred embodiment, the reaction temperature of the secondary reactor is 50-55°C, and the reaction time is 0.9-1.1h.

[0024] As a preferred embodiment, the reaction temperature of the secondary reactor is 58° C. and the reaction time is 1 h.

[0025] In the present application, the molar ratio of propionic acid to thionyl chloride is 1:(0.5-0.8), and a two-stage reactor is used to promote the reaction to proceed in the direction of generating propionyl chloride, while reducing the residual thionyl chloride and improving the purity of propionyl chloride. It is speculated that the possible reason is that when the amount of thionyl chloride used is small, the degree of reaction is small. By using a two-stage reactor, the reaction temperature is further increased, which can promote the reaction to proceed in the direction of generating propionyl chloride to a certain extent, improve the purity of propionyl chloride and improve the yield of propionyl chloride.

[0026] As a preferred embodiment, the temperature of the maturation tower is 65-80°C, and the residence time is 1-2.5h.

[0027] As a preferred embodiment, the temperature of the aging tower is 70-75°C, and the residence time is 1.5-2h.

[0028] As a preferred embodiment, the temperature of the aging tower is 75° C. and the residence time is 1.5 h.

[0029] As a preferred embodiment, the top temperature of the continuous distillation tower is 78-81°C, and the bottom temperature is 142-150°C.

[0030] As a preferred embodiment, the top temperature of the continuous distillation tower is 79-80°C, and the bottom temperature is 145-146°C.

[0031] As a preferred embodiment, the top temperature of the continuous distillation tower is 79°C, and the bottom temperature is 146°C.

[0032] As a preferred embodiment, the distillation of the by-product gas includes primary distillation and secondary distillation, the distillation tower pressure of the primary distillation is 1-3 MPa, and the distillation tower pressure of the secondary distillation is 1-2 MPa.

[0033] As a preferred embodiment, the distillation tower pressure of the primary distillation is 2-3 MPa, and the distillation tower pressure of the secondary distillation is 1-1.5 MPa.

[0034] As a preferred implementation, the distillation tower pressure of the primary distillation is 2 MPa, and the distillation tower pressure of the secondary distillation is 1 MPa.

[0035] In the traditional process, the byproduct hydrogen chloride usually contains 2%-5% sulfur dioxide after recovery. The recovered sulfur dioxide is absorbed as sodium sulfite, which is doped with 2% sodium chloride. The purity of the recovered sulfur dioxide and hydrogen chloride is not high, and they can only be used as raw materials with low added value or as solid waste treatment without added value. In this application, the tail gas is deep cooled and compressed, and then a 2MPa and 1MPa distillation tower are used in combination for distillation treatment, which can accurately separate hydrogen chloride and sulfur dioxide, improve the purity of hydrogen chloride and sulfur dioxide, and increase the added value of the tail gas.

[0036] As a preferred embodiment, the catalyst is selected from one of 4-dimethylaminopyridine and N,N-dimethylformamide.

[0037] As a preferred embodiment, the catalyst is 4-dimethylaminopyridine.

[0038] As a preferred embodiment, the added amount of the catalyst is 1‰-3‰ of the weight of the propionic acid.

[0039] The second aspect of the present invention provides an application of a clean production process of propionyl chloride, which is applied to the production of propionyl chloride.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) In the clean production process of propionyl chloride of the present invention, propionic acid and thionyl chloride are prepared in a molar ratio of 1:(0.5-0.8), which can reduce the content of thionyl chloride in propionyl chloride, improve the purity of propionyl chloride, and increase the yield of downstream products.

[0042] (2) In the clean production process of propionyl chloride described in the present invention, the byproduct gas is cryogenically cooled at -25°C to recover thionyl chloride and propionyl chloride, and then enters a compressor, is distilled in a 2MPa distillation tower to obtain hydrogen chloride, and is distilled in a 1MPa distillation tower to obtain sulfur dioxide. The obtained hydrogen chloride and sulfur dioxide have high purity, thus avoiding the result of mixing hydrogen chloride and sulfur dioxide, and the byproduct has high added value.

[0043] (3) The clean production process of propionyl chloride of the present invention comprises a first reactor for reaction at 30-45° C. for 0.5-1.5 h and a second reactor for reaction at 40-65° C. for 0.5-1.5 h, which can promote the reaction process, increase the reaction degree of thionyl chloride, and reduce the residue of dichlorothionyl.

[0044] (4) The clean production process of propionyl chloride of the present invention can further reduce the consumption of raw materials by recovering thionyl chloride and propionyl chloride carried by tail gas, and the catalyst can be reused, thereby reducing the production cost and having high economic value.

[0045] (5) The clean production process of propionyl chloride of the present invention does not require the treatment of solid waste, is clean and environmentally friendly, and can obtain propionyl chloride with a purity greater than 99%, hydrogen chloride and sulfur dioxide gas with a purity greater than 99.5%, with high product quality and high added value. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a process flow chart of the clean production process of propionyl chloride.

[0047] In the figure: 1. primary reactor; 2. secondary reactor; 3. maturation tower; 4. de-lightening tower, 5. continuous distillation tower; 6. washing tower; 7. deep cooling device; 8. compressor; 9. primary distillation device; 10. secondary distillation device. DETAILED DESCRIPTION

[0048] Example 1

[0049] A clean production process for propionyl chloride comprises the following steps:

[0050] S1 mixes propionic acid with a catalyst, and then feeds it together with thionyl chloride into a reactor;

[0051] After S2 reacts, it enters the maturation tower 3 for maturation, and then enters the light removal tower (continuous) 4 to remove the by-product gas;

[0052] The bottom discharge of S3 light removal tower 4 enters into continuous distillation tower 5, propionyl chloride is taken out from the top of tower, and propionic acid and catalyst are taken out from the bottom of tower and re-enter into reactor for reaction.

[0053] The temperature of the lightness removal tower is 75°C.

[0054] The reactor and the ripening tower 3 both produce by-product gas, which is deeply cooled 7 and then compressed 8 and distilled to obtain pure by-product gas.

[0055] The temperature of the deep cooling 7 is -25°C, the deep cooling device 7 performs continuous deep cooling, and the air pressure after compression by the compressor 8 is 2MPa.

[0056] The by-product gas generated needs to pass through a washing tower 6 before being processed. The washing solvent of the washing tower is thionyl chloride.

[0057] The molar ratio of the propionic acid to the thionyl chloride is 1:0.6.

[0058] The reactor comprises a primary reactor 1 and a secondary reactor 2, and the feeding ratio of thionyl chloride in the primary reactor 1 and the secondary reactor 2 is 2:1.

[0059] The reaction temperature of the primary reactor 1 is 38° C. and the reaction time is 1 h.

[0060] The reaction temperature of the secondary reactor 2 is 58° C. and the reaction time is 1 h.

[0061] The temperature of the aging tower 3 is 75° C., and the residence time is 1.5 h.

[0062] The top temperature of the continuous distillation tower 5 is 79°C, and the bottom temperature is 146°C.

[0063] The distillation of the by-product gas includes a primary distillation 9 and a secondary distillation 10. The distillation tower pressure of the primary distillation 9 is 2 MPa, and the distillation tower pressure of the secondary distillation 10 is 1 MPa.

[0064] The catalyst is 4-dimethylaminopyridine, and the added amount of the catalyst is 2‰ of the weight of propionic acid.

[0065] The color was colorless after 2-methyl-6-ethylaniline color development test.

[0066] Example 2

[0067] A clean production process for propionyl chloride, the specific implementation method is the same as that of Example 1, except that the molar ratio of propionic acid to thionyl chloride is 1:0.8.

[0068] After the 2-methyl-6-ethylaniline test, the color is colorless.

[0069] Example 3

[0070] A clean production process for propionyl chloride, the specific implementation method is the same as that of Example 1, except that the molar ratio of propionic acid to thionyl chloride is 1:0.9.

[0071] The color of the product is reddish brown after the 2-methyl-6-ethylaniline color development test (due to the fact that some thionyl chloride has not reacted completely and enters the product after distillation). The quality does not reach the quality of commercially available products.

[0072] Example 4

[0073] A clean production process for propionyl chloride, the specific implementation method is the same as that of Example 1, except that the distillation tower pressure of the primary distillation 9 is 1.5 MPa, and the distillation tower pressure of the secondary distillation 10 is 0.8 MPa.

[0074] Example 5

[0075] A clean production process for propionyl chloride, the specific implementation method is the same as that of Example 1, except that the distillation tower pressure of the primary distillation 9 is 2.5 MPa, and the distillation tower pressure of the secondary distillation 10 is 1.5 MPa.

[0076] Example 6

[0077] A clean production process for propionyl chloride, the specific implementation method is the same as that of Example 1, except that the reactor includes a primary reactor, the reaction temperature of the primary reactor is 58° C., and the reaction time is 2 hours.

[0078] Performance Testing

[0079] 1. Purity of propionyl chloride: The purity of propionyl chloride was detected by gas chromatography area normalization method.

[0080] 2.2-methyl-6-ethylaniline color development test: Take half of the product of Example 1-6 in a 10mL penicillin vial, and add 2-3 drops of 2-methyl-6-ethylaniline to the vial. Colorless is acceptable, reddish brown is unacceptable.

[0081] 3. Purity of hydrogen chloride: The purity of hydrogen chloride is tested by gas chromatography area normalization method.

[0082] 4. Purity of sulfur dioxide: The purity of sulfur dioxide is tested by gas chromatography area normalization method.

[0083] The test results are shown in Table 1.

[0084] Table 1

[0085]

Claims

1. A clean production process for propionyl chloride, characterized in that, The following steps are involved: S1 mixes propionic acid with a catalyst, and then feeds it together with thionyl chloride into a reactor; After S2 reacts, it enters the maturation tower for maturation, and then enters the light removal tower to remove the by-product gas; The bottom discharge of the S3 light removal tower enters a continuous distillation tower, propionyl chloride is taken out from the top of the tower, and propionic acid and the catalyst are taken out from the bottom of the tower and re-enter the reactor for reaction.

2. The clean production process of propionyl chloride according to claim 1, characterized in that: The reactor and the maturation tower will both produce by-product gas, which is deeply cooled, compressed, and distilled to obtain pure by-product gas.

3. The clean production process of propionyl chloride according to claim 1, characterized in that: The molar ratio of the propionic acid to the thionyl chloride is 1:(0.5-0.8).

4. The clean production process of propionyl chloride according to claim 1, characterized in that: The reactor comprises a primary reactor and a secondary reactor, and the feeding ratio of thionyl chloride in the primary reactor and the secondary reactor is (1-3):

1.

5. The clean production process of propionyl chloride according to claim 4, characterized in that: The reaction temperature of the primary reactor is 30-45°C, and the reaction time is 0.5-1.5h.

6. The clean production process of propionyl chloride according to claim 4, characterized in that: The reaction temperature of the secondary reactor is 40-65° C., and the reaction time is 0.5-1.5 h.

7. The clean production process of propionyl chloride according to claim 1, characterized in that: The temperature of the aging tower is 65-80°C, and the residence time is 1-2.5h.

8. The clean production process of propionyl chloride according to claim 1, characterized in that: The top temperature of the continuous distillation tower is 78-81°C, and the bottom temperature is 142-150°C.

9. The clean production process of propionyl chloride according to claim 2, characterized in that: The distillation of the by-product gas includes primary distillation and secondary distillation. The distillation tower pressure of the primary distillation is 1-3 MPa, and the distillation tower pressure of the secondary distillation is 1-2 MPa.

10. An application of the clean production process of propionyl chloride according to any one of claims 1 to 9, characterized in that: Used in the production of propionyl chloride.

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