Method for preparing 4-hexen-3-one

Abstract

Provided is a method for preparing 4-hexen-3-one. The method comprises the following steps: under the action of a catalyst, subjecting propionyl chloride and propylene to a Friedel-Crafts reaction, and then subjecting the resulting reaction product to alkaline hydrolysis using trimethylamine, so as to obtain 4-hexen-3-one. By using propionyl chloride as a raw material, byproducts difficult to treat are not generated during the production process, and furthermore triethylamine can be recycled and reused; therefore, the production cost of 4-hexen-3-one can be greatly reduced in terms of material cost and treatment cost. Moreover, the method is easy in terms of production and operation, only needs a few production facilities, has a relatively high yield, and is beneficial to large-scale production of 4-hexen-3-one.

Description

A preparation method of 4-hexen-3-one Technical Field

[0001] The invention belongs to the technical field of compound preparation and relates to a preparation method of 4-hexene-3-one. Background Art

[0002] Dimethyldioxycyclohexanecarboxylate is a fragrance monomer with a unique aroma and a good fixative. It is widely used in fine chemical products such as soaps, detergents, high-end perfumes and tobacco. 4-Hexene-3-one is an important intermediate for the synthesis of dimethyldioxycyclohexanecarboxylate. The current synthesis method of dimethyldioxycyclohexanecarboxylate uses propionic anhydride and propylene as raw materials, aluminum chloride catalyst to react to obtain 4-hexene-3-one intermediate, which is then cyclized with dimethyl malonate and the pH is adjusted with acetic acid to obtain the product. The preparation of the 4-hexene-3-one intermediate in this method requires propionic anhydride, which is expensive, and a large amount of propionic acid is produced during the synthesis process, which is difficult to handle. In addition, the yield of 4-hexene-3-one is low, and this synthesis method is not conducive to large-scale production.

[0003] Summary of the Invention

[0004] The present invention aims to address the deficiencies of the prior art and to provide a method for preparing 4-hexen-3-one, which is easy to produce and operate, has mild reaction conditions, does not produce difficult-to-treat substances during the reaction process, has a high yield, and can effectively reduce costs.

[0005] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0006] A method for preparing 4-hexen-3-one comprises the following steps: subjecting propionyl chloride and propylene to a Friedel-Crafts reaction under the action of a catalyst, and then performing alkaline hydrolysis using triethylamine to obtain 4-hexen-3-one.

[0007] In the above scheme, specifically, the method comprises the following steps:

[0008] Under vacuum conditions, keeping the temperature no higher than 20°C, the catalyst is added to the solvent, stirred to dissolve, propionyl chloride is added, stirred thoroughly, and then propylene gas is introduced to carry out Friedel-Crafts reaction. After the reaction is completed, the reaction is quenched with water, and then allowed to stand and separate. The material layer is washed, heated and triethylamine is added to carry out alkaline hydrolysis reaction. After the reaction, the temperature is lowered, hydrochloric acid is added dropwise to separate the layers, and the lower layer is distilled to obtain 4-hexen-3-one.

[0009] Furthermore, the catalyst is one or more of aluminum trichloride, ferric chloride, titanium tetrachloride, and anhydrous zinc chloride, and the solvent is one or more of dichloroethane, dichloromethane, nitromethane, nitrobenzene, and carbon disulfide.

[0010] Furthermore, the propionyl chloride is added dropwise and stirred for at least 1 hour after addition.

[0011] Furthermore, the Friedel-Crafts reaction time is 1 to 2 hours.

[0012] Furthermore, the mass ratio of propionyl chloride, propylene and triethylamine is 32:20 to 26:27.

[0013] Furthermore, the mass ratio of propionyl chloride to catalyst is 1:1 to 1:1.5.

[0014] Furthermore, the temperature is raised to 80-85°C, and the temperature is lowered to no more than 30°C.

[0015] Furthermore, after adding hydrochloric acid dropwise to separate the layers, the lower layer was distilled, and the low-pressure steam was heated to 95° C. and the solvent was recovered by atmospheric distillation. Then, in order to ensure the distillation temperature, the vacuum pump was turned on and the temperature was less than 105° C. to obtain 4-hexen-3-one by distillation.

[0016] Furthermore, after hydrochloric acid was added dropwise to separate the layers, liquid alkali was added dropwise to the aqueous layer, and the temperature was raised to 90° C. to distill and recover triethylamine.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a method for synthesizing 4-hexen-3-one. The method uses propionyl chloride and propylene as raw materials, performs a Friedel-Crafts reaction under catalyst conditions, and then uses triethylamine for alkaline hydrolysis to obtain 4-hexen-3-one. The method has low cost, mild reaction conditions, does not produce difficult-to-treat byproducts during the reaction process, and has a high reaction yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the embodiments of the present invention, the following briefly describes the drawings involved in the description of the embodiments of the present invention. The drawings described are only used to illustrate the embodiments of the present invention and do not constitute an undue limitation of the present invention. Those skilled in the art may make modifications based on the above drawings through creative efforts.

[0020] FIG1 is a reaction principle equation of the method of the present invention;

[0021] FIG2 is an NMR spectrum of the product obtained by the synthesis method of the present invention;

[0022] FIG3 is a GC chromatogram of the product obtained in Example 5; DETAILED DESCRIPTION

[0023] The exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, the present invention may also be implemented in other forms and is not limited to the described embodiments. Rather, these embodiments are provided to facilitate a better understanding of the present invention for those skilled in the art. Before the reaction, ensure that each reaction equipment is clean and anhydrous.

[0024] Example 1

[0025] The reactor was vacuumed, 300g of dichloroethane was drawn in by vacuum, the temperature was kept at 15°C, 20g of aluminum chloride was added, stirred for 30min, 32g of propionyl chloride was added dropwise, stirred for 1h, 20g of propylene gas was introduced, and the reaction was continued for 2h, 110g of water was added to another quenching kettle, and the temperature was lowered to 15°C. After the reaction was completed, the feed liquid of the reactor was placed in the quenching kettle for hydrolysis, stirred for 1.5h, and transferred to the layering kettle. The layering kettle was allowed to stand for layering, the water layer was treated with sewage, and the material layer was treated with water. Wash, then mix with 27g triethylamine at 80℃, cool to 28℃, stir for 2h, add 90g hydrochloric acid, separate the layers, and send the product layer to the distillation tower for rectification. Send the water layer to the triethylamine kettle, add liquid alkali dropwise, and then heat to 90℃ for distillation to recover triethylamine. After the distillation is completed, start the circulating water and cool to 25℃. Then the waste water goes to the sewage station. Heat the low-pressure steam in the distillation tower to 95℃ and distill at atmospheric pressure to recover dichloroethane. Distill at a temperature below 105℃ to obtain 31g of 4-hexen-3-one with a reaction yield of 90.8%.

[0026] Example 2

[0027] The reactor was vacuumed, 300g of dichloroethane was drawn in by vacuum, the temperature was kept at 18°C, 28.6g of aluminum chloride was added, stirred for 30min, 32g of propionyl chloride was added dropwise, stirred for 1.5h, 22g of propylene gas was introduced, and the reaction was continued for 2h, 110g of water was added to another quenching kettle, the temperature was lowered to 18°C, and after the reaction was completed, the feed liquid of the reactor was placed in the quenching kettle for hydrolysis, stirred for 1.5h, and transferred to the layering kettle. The layering kettle was allowed to stand for layering, the water layer was treated with sewage, and the material layer was allowed to stand for layering. Wash with water, then mix with 27g of triethylamine at 83°C, cool to 30°C, stir for 2h, add 90g of hydrochloric acid, separate the layers, and distill the product layer to the distillation tower for rectification. The water layer is transferred to the triethylamine kettle, and liquid alkali is added dropwise. Then the temperature is raised to 90°C for distillation to recover the triethylamine. After the distillation is completed, the circulating water is turned on and cooled to 28°C. The wastewater then enters the sewage station. The low-pressure steam in the distillation tower is heated to 95°C and distilled at atmospheric pressure to recover dichloroethane. The distillation temperature is less than 105°C to obtain 30.5g of 4-hexen-3-one with a yield of 89%.

[0028] Example 3

[0029] The reactor was vacuumed, and 300g of dichloroethane was drawn in by vacuum, the temperature was maintained at 20°C, 39g of aluminum chloride was added, stirred for 30min, 32g of propionyl chloride was added dropwise, stirred for 2h, 26g of propylene gas was introduced, and the reaction was carried out for 2h. 110g of water was added to another quenching kettle, and the temperature was lowered to 20°C. After the reaction was completed, the feed liquid of the reactor was placed in the quenching kettle for hydrolysis, stirred for 1.5h, and transferred to the layering kettle. The layering kettle was allowed to stand for layering, the water layer was treated with sewage, the material layer was washed with water, and then mixed with 27g of triethylamine at 85°C, cooled to 33°C, stirred for 2h, 90g of hydrochloric acid was added, the layers were separated, and the product layer was distilled to the distillation tower. The water layer was heated to 90°C and distilled to recover triethylamine. After distillation, the circulating water was turned on and cooled to 30°C. The wastewater was then sent to the sewage station. The low-pressure steam in the distillation tower was heated to 95°C and distilled at atmospheric pressure to recover dichloroethane. The distillation temperature was less than 105°C to obtain 30.8g of 4-hexen-3-one with a yield of 90.3%.

[0030] Example 4

[0031] The reactor was vacuumed, 300g of dichloroethane was drawn in by vacuum, the temperature was kept at 18°C, 28.6g of aluminum chloride was added, stirred for 30min, 32g of propionyl chloride was added dropwise, stirred for 1.5h, 22g of propylene gas was introduced, and the reaction was continued for 2h, 110g of water was added to another quenching kettle, the temperature was lowered to 18°C, and after the reaction was completed, the feed liquid of the reactor was placed in the quenching kettle for hydrolysis, stirred for 1.5h, and transferred to the layering kettle. The layering kettle was allowed to stand for layering, the water layer was treated with sewage, and the material layer was used. The mixture was washed with water, then mixed with 27 g of triethylamine at 83 ° C, cooled to 30 ° C, stirred for 2 h, 90 g of hydrochloric acid was added, the layers were separated, the product layer was distilled to the distillation tower, the water layer was taken to the triethylamine kettle, liquid alkali was added dropwise, and then the temperature was raised to 90 ° C for distillation to recover the triethylamine. After the distillation was completed, the circulating water was opened and cooled to 28 ° C, and then the waste water was sent to the sewage station. The low-pressure steam in the distillation tower was heated to 95 ° C and distilled at atmospheric pressure to recover dichloroethane. The distillation temperature was less than 105 ° C to obtain 31.1 g of 4-hexen-3-one with a yield of 91.2%.

[0032] Example 5

[0033] Vacuum 300g of ethylene dichloride into the reactor. Cool the chilled brine to 20°C, add 45g of aluminum trichloride, and stir for 30 minutes. Maintain the temperature below 20°C, then dropwise add 33g of propionyl chloride. After addition, insulate and stir for 2 hours. Slowly introduce 20g of propylene gas and allow to react for 2 hours. Propylene gas is supplied from a propylene vaporizer heated with hot water. Add water to a separate quenching kettle, cool the chilled brine to 20°C, and slowly add the reacted liquid to the hydrolysis process. After hydrolysis is complete, stir for 1 hour. Transfer the mixture to a separate reactor. Let the reactor stand and separate the layers, then decontaminate the water layer. Wash the layer once with water. Transfer the layer to another reactor, heat it to 85°C using low-pressure steam, and dropwise add 28g of triethylamine. After addition, insulate and react for 2 hours. Recirculate water and cool it to 30°C. Add hydrochloric acid dropwise and separate the layers. The product layer is distilled in a distillation tower. The low-pressure steam is heated to 95°C for atmospheric distillation to recover ethylene dichloride. A Roots pump is then activated, and 4-hexen-3-one is distilled at a temperature below 105°C. The aqueous layer is then transferred to a triethylamine kettle, where liquid caustic soda is added dropwise. The temperature is then raised to 90°C for distillation to recover triethylamine. Upon completion of distillation, circulating water is activated to cool the temperature to 25°C, and the wastewater is then sent to the sewage treatment plant.

[0034] The following table is a material balance table for this example.

[0035] It can be seen that no difficult-to-treat substances are produced in the method of the present invention, and triethylamine can be recycled and reused. This method can greatly reduce the production cost of 4-hexen-3-one in terms of material cost and processing cost, and the yield is relatively high, reaching 92.9%.

[0036] For the sake of brevity, not every step of the embodiment can be described in detail. However, those skilled in the art will appreciate that the present invention is not limited to the above description of the operation, as some steps can be adjusted in order. Furthermore, those skilled in the art will also appreciate that the embodiments of the present invention are preferred, and the operations and conditions involved are not necessarily required for the present invention.

[0037] The technical solutions provided by the present invention have been described in detail above, and the application examples have been used to illustrate the principles and implementation methods of the present invention. The examples are only intended to help understand the ideas and basic paths of the present invention. At the same time, those skilled in the art can expand on the specific implementation and application scope based on the ideas of the present invention. In summary, the content of the present invention should not be construed as limiting the understanding of the present invention.

Claims

1. A method for preparing 4-hexen-3-one, characterized in that: The method comprises the following steps: under the action of a catalyst, propionyl chloride and propylene are subjected to Friedel-Crafts reaction, and then triethylamine is used for alkaline hydrolysis to obtain 4-hexene-3-one.

2. The method for preparing 4-hexen-3-one according to claim 1, characterized in that: The method comprises the following steps: Under vacuum conditions, the temperature is maintained at no more than 20°C, the catalyst is added to the solvent, stirred to dissolve, propionyl chloride is added, stirred thoroughly, and propylene gas is then introduced to carry out Friedel-Crafts reaction. After the reaction is completed, the reaction is quenched with water, and then allowed to stand and separate. The material layer is washed, the temperature is raised, and triethylamine is added to carry out alkaline hydrolysis reaction. After the reaction, the temperature is lowered, hydrochloric acid is added dropwise to separate the layers, and the lower layer is distilled to obtain 4-hexen-3-one.

3. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: The catalyst is one or more of aluminum trichloride, ferric trichloride, titanium tetrachloride and anhydrous zinc chloride; the solvent is one or more of ethylene dichloride, dichloromethane, nitromethane, nitrobenzene and carbon disulfide.

4. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: The propionyl chloride is added dropwise and stirred for at least 1 hour after addition.

5. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: The Friedel-Crafts reaction time is 1 to 2 hours.

6. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: The mass ratio of propionyl chloride, propylene and triethylamine is 32:20 to 26:

27.

7. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: The mass ratio of propionyl chloride to the catalyst is 1:1 to 1:1.

5.

8. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: The temperature is raised to 80-85°C, and the temperature is lowered to no higher than 30°C.

9. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: After adding hydrochloric acid dropwise to separate the layers, the lower layer was distilled, the low-pressure steam was heated to 95°C and the solvent was recovered by atmospheric distillation, and then the vacuum pump was turned on and 4-hexen-3-one was obtained by distillation at a temperature below 105°C.

10. The method for preparing 4-hexen-3-one according to claim 2, characterized in that: After hydrochloric acid was added dropwise to separate the layers, liquid alkali was added dropwise to the water layer, and the temperature was raised to 90°C to distill and recover triethylamine.

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