Synthetic method of isopentenoamide sulfate, isopentenoic acid and ester of isopentenoamide sulfate and isopentenoic acid

Abstract

The invention discloses a synthesis method of isopentenoamide sulfate, isopentenoic acid and ester thereof, and the preparation process of the isopentenoamide sulfate is as follows: 3-methyl-2-hydroxybutyronitrile reacts with fuming sulfuric acid to obtain 3-methyl-2-butenamide sulfate, hydrolysis or esterification reaction is continued on the basis to obtain 3-methyl-2-butenamide sulfate, and the 3-methyl-2-butenamide sulfate is obtained. Thus, isopentenoic acid or isopentenoic acid ester can be obtained. The preparation method provided by the invention has the advantages of high target product yield, few three wastes and easiness in treatment, and is an efficient and environment-friendly production method of the isopentenoic acid and the ester thereof.

Description

Technical Field

[0001] The invention belongs to the technical field of compound preparation, relates to the production of chemical raw materials, and specifically relates to a method for synthesizing isopentenylamide sulfate, and a method for synthesizing isopentenyl acid and its ester. Background Art

[0002] Isopentenic acid, also known as 3-methyl-2-butenoic acid and senecioic acid, is often used as an intermediate for synthetic fragrances, medicines and pesticides. Its derivatives, methyl isopentenylate and ethyl isopentenylate, are fragrances; ethyl isopentenylate is highly toxic to mosquitoes, horseflies and lice, but less toxic to humans and mammals. Therefore, ethyl isopentenylate is a highly effective pesticide. Isopentenylic acid can also be used in the synthesis of the renal peptidase inhibitor cilastatin, the antifungal drug ciclopirox olamine and the pesticide methoxymethylthrin.

[0003] There are several main methods for synthesizing isopentanic acid:

[0004] (1) Acetone is used as a raw material, and mesityl oxide is obtained by aldol condensation, and then mesityl oxide is reacted with hypochlorite or hypobromite in a haloform reaction to obtain isopentyl acrylate. The yield is 76.8% based on mesityl oxide. This method for producing isopentyl acrylate has a low total yield, and requires preparation, storage, transportation, and use of hypohalite, which is not conducive to clean production. The synthetic route is shown in formula (I).

[0005]

[0006] (2) Using isobutylene and carbon tetrachloride as raw materials, an addition reaction is carried out in the presence of a copper salt catalyst and under pressure to obtain 1,1,1,3-tetrachloro-3-methylbutane with a yield of 90%, which is then hydrolyzed with sulfuric acid to obtain isopentanic acid with a yield of 80-90%. The total yield of the two-step reaction can reach 70%-80%. The synthesis route is shown in formula (II).

[0007]

[0008] (3) 2-methyl-3-butyn-2-ol is used as the raw material, and 3-methyl-2-butenal is obtained by a Mayer-Schuster rearrangement reaction, and then isopentanic acid is obtained by air oxidation. The total yield is 76.5%. The synthetic route is shown in formula (III).

[0009]

[0010] (4) Acetone and ketene are reacted with zinc thiocyanate as a catalyst to obtain dimethyl propiolactone, which is then hydrolyzed and ring-opened in an acidic aqueous solution and dehydrated to obtain isopentenic acid, with a total yield of 40-50% based on ketene. The synthetic route is shown in formula (IV). This method is disclosed in US Pat. No. 2,450,117A. The raw materials used in this method are obtained by cracking acetic acid, which has limited sources, low yield, and high production cost.

[0011]

[0012] The isopentenic acid is then esterified with alcohol in the presence of a catalyst such as a protonic acid or a solid acid to obtain an isopentenic acid ester. The synthetic route is shown in formula (V).

[0013]

[0014] It is also possible to react isopentanic acid with thionyl chloride to obtain isopentanic acid chloride, which is then reacted with alcohol to obtain isopentanic acid ester. The synthetic route is shown in formula (VI) (Mao Duobin, Journal of Zhengzhou Institute of Light Industry, 1997, 12, 2, 77-80). The yield of isopentanic acid chloride is 89.0%, and the yield of esterification is 57.2-89.2%, of which the yield of methyl ester is 83.1%, the yield of ethyl ester is 89.2%, and the yield of cyclohexanol ester is 57.2%. The total yield is 50.9-79.4%. This method consumes a large amount of thionyl chloride, has a low yield, and produces a large amount of sulfur dioxide and hydrogen chloride gas as by-products, which puts great pressure on environmental protection.

[0015]

[0016] The existing various synthesis methods have one or more problems such as limited original sources, low yield, low economy or environmental friendliness. New synthesis methods need to be developed to meet industrial needs. Summary of the invention

[0017] In view of this, one of the purposes of the present invention is to provide a method for synthesizing isopentenylamide sulfate. The synthesis process is relatively simple and convenient, and the product can be used as a raw material for synthesizing isopentenyl acid and its esters, so as to solve the problems of difficult sources of raw materials for isopentenyl acid and its esters, low yield, high synthesis cost, large amount of three wastes, etc. in the prior art.

[0018] The technical solution is as follows:

[0019] A method for synthesizing isopentenylamide sulfate, the key of which is to react 3-methyl-2-hydroxybutyronitrile with fuming sulfuric acid of a concentration of 100-110% to obtain 3-methyl-2-butenylamide sulfate;

[0020] The molar ratio of the reaction raw materials fuming sulfuric acid and 3-methyl-2-hydroxybutyronitrile is (1-3):1;

[0021] The reaction is carried out under staged temperature control, wherein the temperature is controlled at 70-100° C. when 3-methyl-2-hydroxybutyronitrile and fuming sulfuric acid are mixed in the first stage, and the reaction liquid is heated to 120-150° C. for reaction in the second stage.

[0022] Preferably, the molar ratio of the reaction raw materials fuming sulfuric acid and 3-methyl-2-hydroxybutyronitrile is (1.1-1.5):1.

[0023] Preferably, the reaction temperature of the first stage is 80-95°C, and the reaction temperature of the second stage is 130-140°C.

[0024] Preferably, in the first stage, the two raw materials are mixed by dropwise addition, and the temperature of the reaction liquid is maintained by cooling and temperature control. After the mixing is completed, the reaction is kept warm for a period of time before entering the second stage.

[0025] Preferably, the concentration of oleum is 100-105%.

[0026] The reaction principle is as shown in formula (1).

[0027]

[0028] A second object of the present invention is to provide a method for synthesizing isopentanic acid.

[0029] The technical solution is as follows:

[0030] A synthetic method of isopentanic acid, the key of which is the steps of:

[0031] S1, preparing a mixed solution of 3-methyl-2-buteneamide sulfate and sulfuric acid according to any of the above methods;

[0032] S2, reacting the reaction product of step S1 with water to obtain isopentanic acid and ammonium bisulfate;

[0033] S3, adding ammonia to the reaction product of step S2 to neutralize excess sulfuric acid, and the reaction solution is post-treated to obtain isopentanic acid.

[0034] Preferably, the reaction temperature in step S2 is 80-120°C.

[0035] Preferably, the reaction temperature in step S2 is 90-100°C.

[0036] Preferably, the ratio of the amount of water added to 3-methyl-2-hydroxybutyronitrile in step S2 is (2-8):1.

[0037] Preferably, the ratio of the amount of water added to 3-methyl-2-hydroxybutyronitrile in step S2 is (2-5):1.

[0038] Preferably, the post-processing adopts any of the following methods:

[0039] The reaction solution is crystallized to obtain isopentanic acid, and the crystallization mother liquor is concentrated to obtain ammonium sulfate; or

[0040] After extraction with an organic solvent, an organic phase and an aqueous phase are separated, and the organic phase is concentrated and crystallized to obtain isopentanic acid, and the aqueous phase is concentrated and crystallized to obtain ammonium sulfate.

[0041] Preferably, the organic solvent is an aliphatic halogenated hydrocarbon, an aromatic halogenated hydrocarbon, an ester, a ketone or an ether solvent.

[0042] The reactions in steps S2 and S3 are shown in formulas (2) and (3), respectively.

[0043]

[0044] H2SO4+2NH3→(NH4)2SO4

[0045] NH4HSO4+NH3→(NH4)2SO4 (3).

[0046] A third object of the present invention is to provide a method for synthesizing isopentanylate.

[0047] The technical solution is as follows:

[0048] A method for synthesizing isopentenylate, the key of which is the following steps:

[0049] S1, preparing a mixed solution of 3-methyl-2-buteneamide sulfate and sulfuric acid according to any of the above methods;

[0050] S2, adding water to the reaction product of step S1, and after the hydrolysis is completed, adding an alcohol raw material to react to obtain a mixture of isopentenylate and ammonium bisulfate;

[0051] S3, the product of step S2 is phase-separated, the organic phase is distilled to recover alcohol and obtain the product isopentanate, the aqueous phase is neutralized with ammonia, the alcohol is concentrated to recover alcohol, and the concentrated solution is crystallized to obtain ammonium sulfate.

[0052] Preferably, the alcohol raw material is methanol, ethanol, n-propanol, isopropanol or isobutanol.

[0053] Preferably, the distillation is carried out under normal pressure or reduced pressure.

[0054] Preferably, the reaction temperature in step S2 is 80-120°C.

[0055] Preferably, the reaction temperature in step S2 is 90-100°C.

[0056] Preferably, in step S2, the ratio of the amount of alcohol added to the amount of 3-methyl-2-hydroxybutyronitrile added is (1.5-4):1.

[0057] The reaction in step S2 is respectively as shown in formula (4), and the neutralization reaction is as shown in formula (3).

[0058]

[0059] The beneficial effects of the present invention are as follows: the present invention uses cheap and easily available 3-methyl-2-hydroxybutyronitrile, i.e., isobutyraldehyde cyanohydrin, as a raw material, and efficiently converts the raw material into isopentenylamide sulfate through an amidation reaction; the amidation reaction product does not need to be purified or separated, and can be directly subjected to a hydrolysis reaction or an alcoholysis reaction to obtain a high-purity target product, isopentenyl acid or its ester, with a high yield, thereby greatly reducing the production cost and also greatly reducing the generation of wastewater in the three wastes. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is the high performance liquid chromatography (HPLC) analysis spectrum of the isopentanic acid product obtained in Example 8;

[0061] Figure 2 This is the gas chromatography (GC) analysis spectrum of the methyl isopentanate product obtained in Example 13. DETAILED DESCRIPTION

[0062] The present invention is further described below in conjunction with embodiments and drawings.

[0063] The raw material of the reaction is 3-methyl-2-hydroxybutyronitrile, also known as isobutyraldehyde cyanohydrin. Oleum refers to a sulfuric acid solution of sulfur trioxide, and its concentration content is the content of sulfuric acid converted from all SO3 in the solution.

[0064] (I) Synthesis of prenylated amide sulfate

[0065] Examples 1 to 5

[0066] Synthesis of isopentenylamide sulfate, i.e. 3-methyl-2-butenylamide sulfate, from isobutyraldehyde cyanohydrin:

[0067] First, add 100% to 110% fuming sulfuric acid into a reaction kettle, use cooling to control the temperature, keep the liquid temperature in the reaction kettle not higher than 70-100° C., then drop isobutyraldehyde cyanohydrin, the amount of isobutyraldehyde cyanohydrin and fuming sulfuric acid is shown in Table 1. After the dropwise addition is completed, keep the temperature for a period of time, then heat to 120-150° C. and continue to react for a period of time. After the transposition reaction is completed, the obtained solution can be separated into isopentenylamide sulfate, or directly used as an intermediate raw material for the next step of synthesizing other substances.

[0068] Starting from isobutyraldehyde cyanohydrin raw material, isopentenyl acid or isopentenyl esters can be synthesized via the intermediate product of isopentenylamide sulfate.

[0069] Table 1 Reaction conditions for preparing isopentenylamide sulfate in Examples 1 to 5

[0070]

[0071] (II) Synthesis of isopentanic acid

[0072] Different from the prior art, the present invention first converts isobutyraldehyde cyanohydrin into isopentenylamide sulfate by the above method, and then performs a hydrolysis reaction. Since no intermediate treatment process is required, the reaction can be carried out continuously. Therefore, in Examples 6 to 10, the liquid obtained by the reaction of Examples 1 to 5 is directly used as a reaction raw material, and a certain amount of water is added thereto to perform the reaction, as follows.

[0073] Example 6

[0074] First, the reaction of prenylamide sulfate was carried out according to the method of Example 1. After the transposition reaction was completed, the temperature was lowered to 120° C. for subsequent reaction.

[0075] Then add 4.3 kg of water, cool to 80-85°C, and keep warm for hydrolysis. After the hydrolysis is completed, add ammonia water dropwise to neutralize to pH = 4.0, filter, wash the solid with a small amount of water, and dry to obtain the isopentenic acid product.

[0076] Example 7

[0077] First, the reaction of prenylamide sulfate was carried out according to the method of Example 2. After the transposition reaction was completed, the temperature was lowered to 120° C. for subsequent reaction.

[0078] Then add 4.7 kg of water, cool to 85-90°C, and keep warm for hydrolysis. After the hydrolysis is completed, add ammonia water dropwise to neutralize to pH = 4.0, filter, wash the solid with a small amount of water, and dry to obtain the isopentenic acid product.

[0079] Example 8

[0080] First, the reaction of prenylamide sulfate was carried out according to the method of Example 3. After the transposition reaction was completed, the temperature was lowered to 120° C. for subsequent reaction.

[0081] Then add 6.6 kg of water, cool to 85-90°C, and keep warm for hydrolysis. After the hydrolysis is completed, add ammonia water dropwise to neutralize to pH = 4.0, filter, wash the solid with a small amount of water, and dry to obtain the isopentenic acid product.

[0082] Example 9

[0083] First, the reaction of prenylamide sulfate was carried out according to the method of Example 4. After the transposition reaction was completed, the temperature was lowered to 120° C. for subsequent reaction.

[0084] Then add 8.6 kg of water, cool to 85-90°C, and keep warm for hydrolysis. After the hydrolysis is completed, add ammonia water dropwise to neutralize to pH = 4.0. Add dichloromethane as an extractant, separate the organic phase after extraction, concentrate and crystallize, and dry to obtain isopentanic acid, and concentrate and crystallize the aqueous phase, and dry to obtain ammonium sulfate.

[0085] Example 10

[0086] First, the reaction of prenylamide sulfate was carried out according to the method of Example 5. After the transposition reaction was completed, the temperature was lowered to 120° C. for subsequent reaction.

[0087] Then add 7.9 kg of water, cool to 85-90°C, and keep warm for hydrolysis. After the hydrolysis is completed, add ammonia water dropwise to neutralize to pH = 4.0. Add ethyl acetate as an extractant, extract and separate the organic phase, concentrate and crystallize, and dry to obtain isopentanic acid, and concentrate and crystallize the aqueous phase, and dry to obtain ammonium sulfate.

[0088] According to the supporting facilities and production conditions of the plant, ammonia gas or liquid ammonia can be introduced into the solution after the reaction to neutralize the excess sulfuric acid. When isopentanoic acid is separated by extraction, the extractant can also use other aliphatic halogenated hydrocarbons such as dichloroethane or chloroform, or aromatic halogenated hydrocarbons such as chlorobenzene, o-dichlorobenzene, or other ester solvents such as n-butyl acetate, or ketone solvents such as methyl isobutyl ketone, mesityl oxide, or ether solvents such as ether, isopropyl ether, methyl tert-butyl ether, etc.

[0089] The products obtained in each example were sampled, and the isopentanic acid content was determined by conventional high performance liquid chromatography (HPLC) method, and the yield was calculated, as shown in Table 2. Typical HPLC spectra of the products are shown in Table 2. Figure 1 As shown, the sample is from the product prepared in Example 8.

[0090] Table 2 Reaction conditions for preparing isopentenic acid in Examples 5 to 8

[0091]

[0092]

[0093] Examples 6 to 10 are the subsequent reactions of implementations 1 to 5. The study found that the reaction conversion rate of Examples 1 to 5 directly affects the reaction of hydrolysis to generate isopentanoic acid. Comparing Examples 1 to 5, in the process of forming amide sulfate, if the temperature of the reaction system is kept relatively low in the first stage, the product yield of isopentanoic acid prepared from amide sulfate is higher and the purity is higher; if the temperature of the reaction system is kept relatively high in the first stage, the product yield of isopentanoic acid prepared from amide sulfate is slightly lower, the purity is also reduced, but the reaction time is shorter. Analyzing the reason, since the reaction of isobutyraldehyde cyanohydrin and fuming sulfuric acid in the first stage is an exothermic reaction, there are more side reactions at high temperatures; if the temperature of the reaction system is controlled at a low level, although there are fewer side reactions, the reaction is slower, more refrigerants are required, and energy consumption is increased. In the second stage, the reaction is an endothermic reaction, so the temperature needs to be appropriately increased. If the temperature is low, no reaction or hydroxy acid is generated. If the temperature is too high, side reactions such as polymerization and decomposition are likely to occur. Therefore, maintaining an appropriate reaction temperature can achieve a balance between product yield, purity and energy consumption, and the comprehensive yield is maximized.

[0094] In addition, combined with experimental and theoretical analysis, in the reaction stage of generating isopentenylamide sulfate, using more sulfuric acid in the reaction system is conducive to the conversion of the raw material isobutyraldehyde cyanohydrin, on the one hand because sulfuric acid is excessive relative to isobutyraldehyde cyanohydrin, on the other hand, more sulfuric acid in the system also enhances the fluidity of the reaction solution, promotes mass transfer and heat transfer, thereby promoting a more complete conversion of isobutyraldehyde cyanohydrin. However, more sulfuric acid leads to a waste of sulfuric acid and increases the consumption of ammonia in the subsequent neutralization reaction process.

[0095] In the hydrolysis reaction, the molar ratio of water addition to isobutyraldehyde cyanohydrin in each embodiment is between 2: 1 and 8: 1. When the amount of water added is large, the amount of isopentanoic acid product dissolved in water increases, affecting the yield, and the amount of wastewater is large; when the amount of water added is small, the generated ammonium bisulfate cannot be completely dissolved.

[0096] (III) Synthesis of isopentenylate

[0097] Similar to the preparation of isopentanolic acid, the present invention first converts isobutyraldehyde cyanohydrin into isopentanylamide sulfate by the above method, and then performs a hydrolysis reaction. Since no intermediate treatment process is required, the reaction can be carried out continuously. Therefore, in Examples 11 to 15, the liquid obtained by the reaction of Examples 1 to 5 is directly used as a reaction raw material, and a hydrolysis reaction is first performed. After the hydrolysis is completed, an alcohol is added thereto for reaction. The alcohol raw material can be methanol, ethanol, n-propanol, isopropanol or isobutanol. Taking methanol as an example, the specific preparation process is as follows.

[0098] Embodiment 11

[0099] The solution obtained by the reaction in Example 1 was kept at 120°C, and an appropriate amount of water was added, and then the temperature was lowered to 90-95°C and kept warm for hydrolysis. After the hydrolysis was completed, methanol with a purity of 99% was added, and the reaction was kept warm at 90-95°C for 4 hours. After the reaction was completed, under the conditions of water pump suction and vacuum degree of -0.093MPa, reduced pressure distillation was performed to obtain a mixture of methanol, water and methyl isopentenylate.

[0100] The mixture after vacuum distillation is transferred to a barbed distillation column or a glass flask of a distillation column with glass spring packing, and under the condition of a water pump vacuum of -0.07 to 0.08 MPa, the oil temperature is maintained at 60 to 90°C and the top temperature is maintained at 50 to 60°C, and methanol and water are obtained by vacuum distillation. Replace with an oil pump, maintain the oil temperature at 100 to 139°C and the top temperature at 70 to 80°C, and distill to obtain the methyl isopentenoate product.

[0101] Example 12

[0102] The whole solution obtained by the reaction in Example 2 was cooled to 120°C, an appropriate amount of water was added, and then the temperature was cooled to 95-100°C and kept warm for hydrolysis. After the hydrolysis was completed, methanol with a purity of 99% was added and kept warm for 4 hours at 95-100°C. After the reaction was completed, the methyl isopentenylate product was obtained by distillation and rectification using the method in Example 11.

[0103] Example 13

[0104] The whole solution obtained by the reaction in Example 3 was cooled to 120°C, and an appropriate amount of water was added, and then cooled to 85-90°C and kept warm for hydrolysis. After the hydrolysis was completed, methanol with a purity of 99% was added, and the reaction was kept warm at 85-90°C for 5 hours. After the reaction was completed, the methyl isopentenylate product was obtained by distillation and rectification using the method in Example 11.

[0105] Embodiment 14

[0106] The whole solution obtained by the reaction in Example 4 was cooled to 120°C, an appropriate amount of water was added, and then the temperature was cooled to 105-110°C and kept warm for hydrolysis. After the hydrolysis was completed, methanol with a purity of 99% was added and kept warm for reaction at 105-110°C for 4 hours. After the reaction was completed, the methyl isopentenylate product was obtained by distillation and rectification using the method in Example 11.

[0107] Embodiment 15

[0108] The whole solution obtained by the reaction in Example 5 was cooled to 120°C, an appropriate amount of water was added, and the temperature was further cooled to 115-120°C and kept warm for hydrolysis. After the hydrolysis was completed, methanol with a purity of 99% was added and kept warm for reaction at 115-120°C for 3 hours. After the reaction was completed, the methyl isopentenylate product was obtained by distillation and rectification using the method in Example 11.

[0109] The amounts of reactants and temperature conditions and the reaction yields of Examples 11 to 15 are shown in Table 3. The distillation products obtained in each Example were analyzed by gas chromatography (GC) to determine the content of methyl isopentanate, and the yield was calculated based on the amount of isobutyraldehyde cyanohydrin as the raw material in Examples 1 to 5. The typical GC spectrum of the product is shown in Figure 2 As shown, the sample was prepared from Example 13.

[0110] Table 3 Reaction conditions for preparing methyl isopentanate in Examples 11 to 15

[0111]

[0112]

[0113] Examples 11 to 15 can also be regarded as subsequent reactions of Examples 6 to 10, respectively, and therefore also depend on the conversion rate of the first step amide reaction. At the same time, since the esterification reaction is carried out after the hydrolysis reaction, it is also affected by the amount of water added. When more water is added, the esterification reaction yield will be affected because isopentanic acid dissolves more in water. In comprehensive comparison, the economic ratio of water addition to 3-methyl-2-hydroxybutyronitrile is 2:1 to 5:1. In the esterification step, excess methanol is added to react to promote the conversion of isopentanic acid, and the addition ratio of methanol to 3-methyl-2-hydroxybutyronitrile is about 3:1.

[0114] The present invention uses isobutyric acid cyanohydrin as a raw material, and amidates with sulfuric acid to obtain an isopentenylamide sulfate product, on which a hydrolysis reaction is performed to obtain isopentenic acid, and further esterification reaction is performed after hydrolysis to obtain isopentenic ester. Overall, the amidation process is more critical, especially when preparing isopentenic acid and isopentenic ester, the amidation process affects the conversion rate and yield of subsequent reactions.

[0115] The preparation method of the invention has high yield of target product, less three kinds of waste materials and is easy to handle, and is an efficient and environmentally friendly production method of isopentenic acid and its ester.

[0116] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, ordinary technicians in this field can make various similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the scope of protection of the present invention.

Claims

1. A method for synthesizing isopentenylamide sulfate, characterized in that: The 3-methyl-2-hydroxybutyronitrile is reacted with fuming sulfuric acid having a concentration of 100-110% to obtain the sulfate of 3-methyl-2-buteneamide; The molar ratio of the reaction raw materials fuming sulfuric acid and 3-methyl-2-hydroxybutyronitrile is (1-3):1; The reaction is carried out under staged temperature control, wherein the temperature is controlled at 70-100° C. when 3-methyl-2-hydroxybutyronitrile and fuming sulfuric acid are mixed in the first stage, and the reaction liquid is heated to 120-150° C. for reaction in the second stage.

2. The method for synthesizing isopentenylamide sulfate according to claim 1, characterized in that: The molar ratio of the reaction raw materials fuming sulfuric acid and 3-methyl-2-hydroxybutyronitrile is (1.1-1.5):

1.

3. A method for synthesizing isopentenylamide sulfate according to claim 1 or 2, characterized in that: The reaction temperature of the first stage is 80-95°C, and the reaction temperature of the second stage is 130-140°C.

4. A method for synthesizing isopentenylamide sulfate according to claim 1 or 2, characterized in that: In the first stage, the two raw materials are mixed by dropwise addition, and the temperature of the reaction liquid is maintained by cooling and temperature control. After the mixing is completed, the reaction is kept warm for a period of time before entering the second stage.

5. A method for synthesizing isopentanic acid, characterized in that The steps are: S1, preparing a mixed solution of 3-methyl-2-butenamide sulfate and sulfuric acid according to any one of claims 1 to 4; S2, reacting the reaction product of step S1 with water to obtain isopentanic acid and ammonium bisulfate; S3, adding ammonia to the reaction product of step S2 to neutralize excess sulfuric acid, and the reaction solution is post-treated to obtain isopentanic acid.

6. The method for synthesizing isopentenic acid according to claim 5, characterized in that: The reaction temperature in step S2 is 80-120°C.

7. The method for synthesizing isopentenic acid according to claim 5, characterized in that: The post-processing adopts any of the following methods: The reaction solution is crystallized to obtain isopentanic acid, and the crystallization mother liquor is concentrated to obtain ammonium sulfate; or After extraction with an organic solvent, an organic phase and an aqueous phase are separated, and the organic phase is concentrated and crystallized to obtain isopentanic acid, and the aqueous phase is concentrated and crystallized to obtain ammonium sulfate.

8. A method for synthesizing isopentenylate, characterized in that The steps are: S1, preparing a mixed solution of 3-methyl-2-butenamide sulfate and sulfuric acid according to any one of claims 1 to 4; S2, adding water to the reaction product of step S1, and after the hydrolysis is completed, adding an alcohol raw material to react to obtain a mixture of isopentenylate and ammonium bisulfate; S3, the product of step S2 is phase-separated, the organic phase is distilled to recover alcohol and obtain the product isopentanate, the aqueous phase is neutralized with ammonia, the alcohol is concentrated to recover alcohol, and the concentrated solution is crystallized to obtain ammonium sulfate.

9. The method for synthesizing isopentenyl ester according to claim 8, characterized in that: The alcohol raw material is any one of methanol, ethanol, n-propanol, isopropanol or isobutanol.

10. The method for synthesizing isopentenyl ester according to claim 8, characterized in that: The distillation is carried out under normal pressure or reduced pressure. The reaction temperature in step S2 is 80-120°C.

Images