A method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste

Abstract

The present invention discloses a method for extracting 5-phenylpentane-2-enoic acid from cinnamaldehyde waste material. The method comprises the following steps: cinnamaldehyde waste material is fully dissolved with a first organic solvent to obtain a cinnamaldehyde waste material solution; alkali is added to the cinnamaldehyde waste material solution to carry out the first neutralization reaction to obtain a neutralized solution; activated carbon is added to the neutralized solution for adsorption decolorization, then filtered to obtain a filtrate; the filtrate is separated and an inorganic layer is taken; acidification is performed in the inorganic layer to obtain an acidified solution; a second organic solvent is added to the acidified solution for extraction, and then the organic layer is dried and dewatered, distilled under reduced pressure, and crystallized by cooling to obtain 5-phenylpentane-2-enoic acid. The present invention can successfully separate 5-phenylpentane-2-enoic acid from cinnamaldehyde waste material, and carboxylic acid crystal purity is ≥98%, significantly improving the added value of cinnamaldehyde waste material, fully utilizing resources, turning waste into treasure, with extremely high economic benefit and environmental benefit.

Description

Technical Field

[0001] The invention relates to the technical field of cinnamaldehyde waste treatment, in particular to a method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste. Background Art

[0002] Cinnamaldehyde is an aldehyde-like organic compound, a yellow, viscous liquid found in large quantities in plants such as cinnamon. Commonly referred to as cinnamaldehyde, cinnamaldehyde occurs naturally in essential oils such as Sri Lankan cinnamon oil, cassia bark oil, patchouli oil, hyacinth oil, and rose oil. It is a widely used food additive and chemical raw material. Cinnamaldehyde can be used to prepare flavorings for meats, condiments, oral care products, chewing gum, and candy. Cinnamaldehyde not only has numerous applications in the chemical industry but also plays an indispensable role in the pharmaceutical field. It is reported to have antibacterial, antiseptic, and anti-ulcer properties, and can also enhance gastric and intestinal motility. In short, cinnamaldehyde can be used as a raw material in itself, added to various topical and finished pharmaceuticals, and can be further processed and synthesized into many powerful drugs.

[0003] There are many methods for preparing cinnamaldehyde. The most commonly used method is the aldol condensation method, which is to condense benzaldehyde and acetaldehyde in the presence of dilute alkali. The reaction formula is as follows:

[0004]

[0005] The aldol condensation reaction mechanism readily derives the reaction process of benzaldehyde and acetaldehyde under alkaline conditions: acetaldehyde first loses its active α-hydrogen in alkaline conditions to form an enolate, which then undergoes a nucleophilic addition reaction with benzaldehyde. The resulting hydroxyketone loses a molecule of water, yielding the product, cinnamaldehyde. However, due to the difficulty in controlling the reaction process during industrialization, cinnamaldehyde often undergoes further aldol condensation to produce 5-phenylpenta-2,4-dienal, which then undergoes intramolecular or intermolecular disproportionation to produce 5-phenylpent-2-enoic acid.

[0006]

[0007] After excessive polymerization of benzaldehyde and acetaldehyde, an insoluble polymer precipitates at the bottom of the reactor, ultimately forming solid cinnamaldehyde waste. During precipitation, it absorbs the carboxylic acid byproducts generated during the reaction. Due to the large number of byproducts in the waste and the presence of over-polymerized components, traditional methods can result in slow filtration, membrane clogging, and impure products. Adding common filter aids such as diatomaceous earth, which physically aid filtration, is also ineffective during filtration. This makes the extraction of carboxylic acids from cinnamaldehyde waste difficult and costly. Currently, it is mostly added to fertilizers for utilization, resulting in low added value. The large amount of organic carboxylic acids in the waste are not fully utilized, resulting in a waste of resources.

[0008] Therefore, it is necessary to address the resource waste phenomenon caused by the under-utilization of 5-phenylpent-2-enoic acid in the above-mentioned cinnamaldehyde waste and invent a method that can fully utilize cinnamaldehyde waste and extract 5-phenylpent-2-enoic acid therefrom to increase resource utilization and reduce the generation of industrial waste residue. Summary of the Invention

[0009] The purpose of the present invention is to overcome the above technical deficiencies and propose a method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste, thereby solving the technical problem in the prior art that a large amount of organic carboxylic acids in cinnamaldehyde waste are not fully utilized, resulting in waste of resources.

[0010] The present invention provides a method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste, comprising the following steps:

[0011] dissolving the cinnamaldehyde waste material in a first organic solvent to obtain a cinnamaldehyde waste material solution;

[0012] adding alkali to the cinnamaldehyde waste solution to perform a first neutralization reaction to obtain a neutralized solution;

[0013] Adding activated carbon to the neutralized solution for adsorption and decolorization, followed by filtering to obtain a filtrate;

[0014] The filtrate is separated and the inorganic layer is taken;

[0015] adding acid to the inorganic layer to acidify it and obtain an acidified solution;

[0016] A second organic solvent is added to the acidified liquid for extraction, and then the organic layer is dried to remove water, distilled under reduced pressure, and crystallized at a lower temperature to obtain 5-phenylpent-2-enoic acid.

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

[0018] The present invention can successfully separate 5-phenylpent-2-enoic acid from cinnamaldehyde waste, and the purity of the carboxylic acid crystals is ≥98%, thereby significantly improving the added value of the cinnamaldehyde waste, fully utilizing resources, turning waste into treasure, and having extremely high economic and environmental benefits. In addition, by adopting the process of the present invention, it is easy to extract carboxylic acid substances from the cinnamaldehyde waste and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a process flow chart of one embodiment of the method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste provided by the present invention;

[0020] Figure 2 This is a process flow chart of an embodiment of a process for recovering cinnamaldehyde waste from cinnamaldehyde production wastewater according to the present invention;

[0021] Figure 3 The nuclear magnetic resonance spectroscopy of 5-phenylpent-2-enoic acid obtained in Example 1 of the present invention is as follows: 1 H NMR spectra;

[0022] Figure 4 The nuclear magnetic resonance spectroscopy of 5-phenylpent-2-enoic acid obtained in Example 1 of the present invention is as follows: 13 C NMR spectrum;

[0023] Figure 5 This is a diagram of the crystal structure of 5-phenylpent-2-enoic acid obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] See also Figure 1 The present invention provides a method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste, comprising the following steps:

[0026] S1, fully dissolving the cinnamaldehyde waste material with a first organic solvent to obtain a cinnamaldehyde waste material solution;

[0027] S2, adding alkali to the above-mentioned cinnamaldehyde waste solution to carry out a first neutralization reaction to obtain a neutralized solution;

[0028] S3, adding activated carbon to the neutralized solution for adsorption and decolorization, followed by filtering to obtain a filtrate;

[0029] S4, separating the filtrate and taking the inorganic layer;

[0030] S5, adding acid to the inorganic layer to acidify it and obtain an acidified solution;

[0031] S6. Add a second organic solvent to the above acidified liquid for extraction, then dry the organic layer to remove water, distill under reduced pressure, and crystallize at reduced temperature to obtain 5-phenylpent-2-enoic acid.

[0032] When improving the present invention, the inventor started with the composition of cinnamaldehyde waste material, analyzed that the composition in cinnamaldehyde waste material is more complicated, but through liquid chromatography analysis, the proportion of a certain type of carboxylic acid substance in the waste material is higher (some samples are about 35%), and the substance in addition is polymer, inorganic salt and other impurities. Due to the existence of polymer, huge difficulty has been brought to the recovery of organic carboxylic acid. Its main performance is that if the impurities such as the above-mentioned polymer are removed by filtering, it is very easy to have the phenomenon such as filtering difficulty, clogging filter membrane, which has brought great difficulty to the carboxylic acid substance in recycling cinnamaldehyde. The inventor added various adsorbents to purify waste material in subsequent experiments, and found that the effect is still not obvious, and it is still difficult to extract the carboxylic acid substance in the waste material.

[0033] Based on these difficulties, the inventors analyzed the characteristics of cinnamaldehyde waste and first used an acid-base neutralization reaction to convert the carboxylic acid into a water-soluble salt, thereby increasing the carboxylic acid's water solubility and significantly reducing membrane clogging. Subsequently, activated carbon adsorption was used to remove ions and pigments from the solution. Ethyl acetate-soluble polymers were then removed from the cinnamaldehyde waste solution by separation. The water-soluble carboxylate salt was then converted into carboxylic acid through acidification. Finally, 5-phenylpent-2-enoic acid with a purity of ≥98% was obtained through extraction, drying and dehydration, vacuum distillation, and cooling crystallization. This is why the present invention was proposed.

[0034] In the present invention, the cinnamaldehyde waste is formed by the excessive polymerization of benzaldehyde and acetaldehyde during the production of cinnamaldehyde, which forms a polymer precipitate insoluble in the system and adsorbs carboxylic acid byproducts generated in the precipitation process.

[0035] When separating and purifying cinnamaldehyde, a large amount of water is often added for back extraction, thus generating a large amount of wastewater containing cinnamaldehyde waste. Figure 2 In some specific embodiments of the present invention, cinnamaldehyde waste is obtained by treating cinnamaldehyde production wastewater, and the specific treatment steps are as follows:

[0036] The cinnamaldehyde production wastewater is cooled in an ice bath and then filtered to obtain an aqueous phase and a solid phase;

[0037] The aqueous phase is subjected to azeotropic distillation to separate acetaldehyde and benzaldehyde, and the remaining wastewater containing polyacetaldehyde (polyacetaldehyde and other macromolecules) is acidified to undergo acid hydrolysis, and the reaction solution is then distilled to separate acetaldehyde, and the remaining mixture is filtered to obtain cinnamaldehyde waste; and / or,

[0038] The solid phase is dissolved in a third organic solvent, and then a base is added to carry out a second neutralization reaction. Finally, the cinnamaldehyde waste is obtained by liquid separation and organic layer concentration.

[0039] The temperature of the azeotropic distillation is 50-70°C, preferably 55-65°C.

[0040] In the acidolysis reaction process, the acid used is sulfuric acid with a mass fraction of 90-98%, and the ratio of the wastewater containing polyacetaldehyde to concentrated sulfuric acid is 1 kg: (0.01-0.03) mL; the temperature of the acidolysis reaction is 55-80° C., preferably 55-70° C., and the acidolysis reaction time is 4-6 hours.

[0041] The distillation temperature is 50-80°C, preferably 55-75°C.

[0042] The third organic solvent is at least one of ethyl acetate, methyl tert-butyl ether, diisopropyl ether, methanol, ethanol, and dichloromethane, preferably ethyl acetate; the dosage ratio of the solid phase to the third organic solvent is 0.8-2 kg:1 L.

[0043] In the second neutralization reaction process, the alkali used is a sodium hydroxide solution or potassium hydroxide solution with a mass fraction of 10%-30%, and the mass ratio of the solid phase to the alkali is 1:(0.1-0.4); the temperature of the second neutralization reaction is 50-60°C, and the time of the second neutralization reaction is 4-6h.

[0044] In this embodiment, before the cinnamaldehyde waste material is fully dissolved in the first organic solvent, the relative content of carboxylic acid in the cinnamaldehyde waste material sample can be detected by liquid chromatography to facilitate subsequent testing of the recovery rate of the carboxylic acid.

[0045] In some specific embodiments of the present invention, the mass content of 5-phenylpent-2-enoic acid in the cinnamaldehyde waste is about 35%.

[0046] In this embodiment, in order to improve the dissolution effect, the cinnamaldehyde waste material is fully dissolved in the first organic solvent in the form of powder. Further, the cinnamaldehyde waste material powder is obtained by fully grinding the cinnamaldehyde waste material.

[0047] In this embodiment, the first organic solvent is at least one of ethyl acetate, methyl tert-butyl ether, diisopropyl ether, methanol, ethanol, and dichloromethane, preferably ethyl acetate. The mass concentration of the cinnamaldehyde waste solution is 10%-20%. If the waste concentration is too high, the system becomes more viscous and reduces reactivity. If the waste concentration is too low, solvent consumption and the number of treatments increase, thereby increasing processing costs.

[0048] The present invention does not limit the type of base used in the first neutralization reaction process, and those skilled in the art can select it according to actual conditions. For example, it can be an inorganic base such as sodium hydroxide, potassium hydroxide, and ammonia water.

[0049] In some specific embodiments of the present invention, the base is sodium hydroxide. The present invention uses sodium hydroxide as the base, which requires less addition and saves costs.

[0050] In some more specific embodiments of the present invention, the base is added to the system in the form of an aqueous solution with a mass concentration of 10%-20%; the mass ratio of the cinnamaldehyde waste to the base is 1:(0.8-2). If the amount of base added is too small, the carboxylic acid reaction is incomplete, reducing the yield. If the amount of base added is too large, the processing cost will increase.

[0051] In the present embodiment, the amount of activated carbon added is 20%-30% of the mass of the cinnamaldehyde waste material; during the adsorption decolorization process, the decolorization temperature is 30-60°C, preferably 30-50°C, and the decolorization time is 20-100min, preferably 80-90min. The inventors found during the experiment that if the neutralization solution is directly separated, the viscosity of the neutralization solution is too large and subsequent separation operations cannot be performed; and the inventors screened different decolorization temperatures and decolorization times and found that within this temperature and time range, the carboxylic acid crystals have the highest purity (≥99%). If the temperature is too high, the first organic solvent evaporates too quickly, and if the temperature is too low or the holding time is too short, the impurity adsorption is insufficient.

[0052] In this embodiment, in step S4, the organic layer obtained by separation can be extracted with water, and the inorganic layers can be combined to improve the recovery rate of 5-phenylpent-2-enoic acid. Furthermore, the number of extractions is 2-3 times.

[0053] The present invention does not limit the type and concentration of the acid solution used in the acidification process, and those skilled in the art can select it according to actual conditions. For example, it can be an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid.

[0054] In some specific embodiments of the present invention, during the acidification process, the acid solution is hydrochloric acid, and the mass concentration of hydrochloric acid is 15%-20%; the final pH is adjusted to 2-3. If the pH is too high, the excess hydrochloric acid increases the cost, and if it is too low, the carboxylate cannot be completely converted into carboxylic acid.

[0055] In this embodiment, the second organic solvent is ethyl acetate, methyl tert-butyl ether, diisopropyl ether, methanol, ethanol, dichloromethane, etc., preferably ethyl acetate; the volume ratio of the acidifying liquid to the second organic solvent is 1: (0.5-2), preferably 1: 1; the number of extractions is 2-3 times; the temperature of the reduced pressure distillation is 45-60 ° C, preferably 50 ° C, and the temperature of the cooling crystallization is -5-0 ° C.

[0056] In the following embodiments of the present invention, unless otherwise specified, the sources of cinnamaldehyde waste are as follows:

[0057] ① 15 kg of cinnamaldehyde production wastewater was cooled in an ice bath and then filtered to obtain 14 kg of aqueous phase and 1 kg of solid phase;

[0058] ② The aqueous phase in step (1) was subjected to azeotropic distillation at 65° C. to separate 3 kg of an aqueous solution containing benzaldehyde and acetaldehyde. The remaining polyacetaldehyde wastewater (polyacetaldehyde and other macromolecules) was then added to 200 mL of 90% concentrated sulfuric acid at 60° C. for acid hydrolysis. After 5 hours, the reaction solution was distilled at 65° C. to separate 1.1 kg of an acetaldehyde aqueous solution. The remaining mixture was then filtered to obtain 0.26 kg of a macromolecular polymer.

[0059] ③ After dissolving the solid phase in ①, add 1 L of ethyl acetate, then add 200 mL of 20% sodium hydroxide at 50°C for a second neutralization reaction for 4 hours. After the reaction is complete, separate the liquids and concentrate the organic phase to obtain 0.15 kg of macromolecular polymer.

[0060] The macromolecular polymers obtained in the above steps ② and ③ are combined as cinnamaldehyde waste.

[0061] Example 1

[0062] (1) taking a cinnamaldehyde waste sample and detecting the relative content of carboxylic acids in the sample by liquid chromatography. The test results show that the type of carboxylic acid contained in the cinnamaldehyde waste is 5-phenylpent-2-enoic acid, with a content of about 35%;

[0063] (2) 400 g of cinnamaldehyde waste sample was first thoroughly ground using a mortar to obtain waste powder;

[0064] (3) 400 g of waste powder was fully dissolved in 2000 g of ethyl acetate to obtain a homogeneous ethyl acetate solution of the waste;

[0065] (4) adding 2000 mL of 20% sodium hydroxide solution to the homogeneous ethyl acetate solution of the waste and stirring thoroughly;

[0066] (5) Add 120 g of activated carbon to the solution in (4), heat at 50°C for 90 min for adsorption decolorization, and remove the activated carbon by filtering with filter paper;

[0067] (6) Separate the solution in (5), and extract the organic layer obtained by separation with water for 3 times, and combine the inorganic layers;

[0068] (7) Add 1000 mL of 20% hydrochloric acid solution to the inorganic layer in (6) to adjust the pH to a final pH of 2-3;

[0069] (8) 3000 mL of ethyl acetate was added to the solution in (7) for extraction, and the extraction times were 3 times. The solution was dried to remove water, and distilled under reduced pressure at 50°C. The temperature was lowered to 0°C for crystallization to obtain 110 g of 5-phenylpent-2-enoic acid with a yield of 27.5% and a purity of 99.9%.

[0070] The experiment was repeated many times, and the yield was 25%-30%, and the purity of the carboxylic acid crystals was ≥99%.

[0071] See also Figure 3-5 ,pass Figure 3-5 It can be seen that the product obtained from the treated waste is 5-phenylpent-2-enoic acid with high purity, indicating that this embodiment successfully extracted 5-phenylpent-2-enoic acid from the cinnamaldehyde waste, and achieved a certain yield and purity, thereby increasing the added value of the cinnamaldehyde waste.

[0072] Example 2

[0073] (1) taking a cinnamaldehyde waste sample and detecting the relative content of carboxylic acids in the sample by liquid chromatography. The test results show that the type of carboxylic acid contained in the cinnamaldehyde waste is 5-phenylpent-2-enoic acid, with a content of about 35%;

[0074] (2) 400 g of cinnamaldehyde waste sample was first thoroughly ground using a mortar to obtain waste powder;

[0075] (3) 400 g of waste powder was fully dissolved in 2000 g of dichloromethane to obtain a homogeneous dichloromethane solution of the waste;

[0076] (4) Add 2000 mL of 20% sodium hydroxide solution to the homogeneous dichloromethane solution of the waste and stir thoroughly;

[0077] (5) Add 120 g of activated carbon to the solution in (4), heat at 30°C for 90 min for adsorption and decolorization, and remove the activated carbon by filtering with filter paper;

[0078] (6) Separate the solution in (5), extract the organic layer obtained by separation with water, extract three times, and combine the inorganic layers;

[0079] (7) Add 1000 mL of 20% hydrochloric acid solution to the inorganic layer in (6) to adjust the pH to a final pH of 2-3;

[0080] (8) 3000 mL of ethyl acetate was added to the solution in (7) for extraction 3 times, and the mixture was dried to remove water, and distilled under reduced pressure at 50°C. The mixture was cooled to 0°C for crystallization to obtain 80 g of 5-phenylpent-2-enoic acid with a yield of 20% and a purity of 99.9%.

[0081] The experiment was repeated many times, and the yield was 15%-20% and the purity was ≥99%. It can be seen that the use of dichloromethane has disadvantages such as low yield, high price, environmental unfriendliness and high toxicity.

[0082] Example 3

[0083] (1) taking a cinnamaldehyde waste sample and detecting the relative content of carboxylic acids in the sample by liquid chromatography. The test results show that the type of carboxylic acid contained in the cinnamaldehyde waste is 5-phenylpent-2-enoic acid, with a content of about 35%;

[0084] (2) 400 g of cinnamaldehyde waste sample was first thoroughly ground using a mortar to obtain waste powder;

[0085] (3) 400 g of waste powder was fully dissolved in 2000 g of methanol to obtain a homogeneous methanol solution of the waste;

[0086] (4) Add 2000 mL of 20% sodium hydroxide solution to the homogeneous methanol solution of the waste and stir thoroughly;

[0087] (5) Add 120 g of activated carbon to the solution (4) and heat at 50°C for 90 min for adsorption decolorization. Remove the activated carbon by filtering with filter paper.

[0088] (6) Separate the solution in (5), extract the organic layer obtained by separation with water, extract three times, and combine the inorganic layers;

[0089] (7) Add 1000 mL of 20% hydrochloric acid solution to the inorganic layer in (6) to adjust the pH to a final pH of 2-3;

[0090] (8) 3000 mL of ethyl acetate was added to the solution in (7) for extraction 3 times, and the mixture was dried to remove water, and distilled under reduced pressure at 50°C. The mixture was cooled to 0°C for crystallization to obtain 30 g of 5-phenylpent-2-enoic acid with a yield of 7.5% and a purity of 99%.

[0091] The yield of repeated experiments was 5%-10%, and the purity was ≥98%, which was too low.

[0092] The data in Examples 1-3 show that the use of an aqueous sodium hydroxide solution / organic solvent system to carry out an acid-base neutralization reaction with the carboxylic acid in the waste material can significantly reduce blockage in polymer filtration and improve the purity of the obtained carboxylic acid product. It also optimizes the production process of cinnamaldehyde and facilitates its continuous production.

[0093] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste, characterized in that: The following steps are involved: dissolving the cinnamaldehyde waste material in a first organic solvent to obtain a cinnamaldehyde waste material solution; adding alkali to the cinnamaldehyde waste solution to perform a first neutralization reaction to obtain a neutralized solution; adding activated carbon to the neutralized solution for adsorption and decolorization, followed by filtering to obtain a filtrate; The filtrate is separated to take the inorganic layer; adding acid to the inorganic layer to acidify it and obtain an acidified solution; A second organic solvent is added to the acidified liquid for extraction, and then the organic layer is dried to remove water, distilled under reduced pressure, and crystallized at a lower temperature to obtain 5-phenylpent-2-enoic acid; wherein, The cinnamaldehyde waste is obtained by treating cinnamaldehyde production wastewater, and the treatment steps are as follows: The cinnamaldehyde production wastewater is cooled in an ice bath and then filtered to obtain an aqueous phase and a solid phase; The aqueous phase is subjected to azeotropic distillation to separate acetaldehyde and benzaldehyde, and then acid is added to the wastewater containing polyacetaldehyde remaining after the azeotropic distillation to perform an acid hydrolysis reaction, and then the reaction solution is subjected to distillation to separate acetaldehyde, and then the mixture remaining after the distillation is filtered to obtain cinnamaldehyde waste; and / or, The solid phase is dissolved in a third organic solvent, and then a base is added to perform a second neutralization reaction. Finally, the cinnamaldehyde waste is obtained by liquid separation and organic layer concentration.

2. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: The first organic solvent is at least one of ethyl acetate, methyl tert-butyl ether, diisopropyl ether, methanol, ethanol, and dichloromethane; and the mass concentration of the cinnamaldehyde waste solution is 10%-20%.

3. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: During the first neutralization reaction, the alkali is added to the system in the form of an aqueous solution, and the mass concentration of the alkali solution is 10%-20%; the mass ratio of the cinnamaldehyde waste to the alkali is 1:(0.8-2).

4. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: The added amount of the activated carbon is 20%-30% of the mass of the cinnamaldehyde waste.

5. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: During the adsorption decolorization process, the decolorization temperature is 30-60°C and the decolorization time is 20-100 minutes.

6. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: During the acidification process, the final pH was adjusted to 2-3.

7. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: The second organic solvent is at least one of ethyl acetate, methyl tert-butyl ether, diisopropyl ether, methanol, ethanol, and dichloromethane; the volume ratio of the acidified liquid to the second organic solvent is 1:(0.5-2).

8. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: The temperature of the reduced pressure distillation is 45-60°C, and the temperature of the cooling crystallization is -5-0°C.

9. The method for extracting 5-phenylpent-2-enoic acid from cinnamaldehyde waste according to claim 1, characterized in that: During the azeotropic distillation process, the temperature of the azeotropic distillation is 50-70°C; during the acidolysis reaction process, the acid used is sulfuric acid with a mass fraction of 90-98%, and the amount ratio of the wastewater containing polyacetaldehyde to concentrated sulfuric acid is 1kg:(0.01-0.03)mL; the temperature of the acidolysis reaction is 55-80°C, and the acidolysis reaction time is 4-6h; during the distillation process, the distillation temperature is 50-80°C; the third organic solvent is at least one of ethyl acetate, methyl tert-butyl ether, diisopropyl ether, methanol, ethanol, and dichloromethane, and the amount ratio of the solid phase to the third organic solvent is 0.8-2kg:1L; during the second neutralization reaction process, the alkali used is sodium hydroxide solution or potassium hydroxide solution with a mass fraction of 10%-30%, and the mass ratio of the solid phase to the alkali is 1:(0.1-0.4); the temperature of the second neutralization reaction is 50-60°C, and the second neutralization reaction time is 4-6h.

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