CN115433129A - Method for preparing pyrazole compound - Google Patents
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- CN115433129A CN115433129A CN202110615731.7A CN202110615731A CN115433129A CN 115433129 A CN115433129 A CN 115433129A CN 202110615731 A CN202110615731 A CN 202110615731A CN 115433129 A CN115433129 A CN 115433129A
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- C07D231/00—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings
- C07D231/02—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings
- C07D231/10—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D231/14—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
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Abstract
The invention relates to the technical field of herbicide preparation, and discloses a method for preparing pyrazole compounds. The method of the invention comprises the following steps: in the presence of a first solvent and a first alkaline substance, carrying out a ring closure reaction on a compound shown as a formula (II) and methylhydrazine to obtain a compound shown as a formula (I); wherein in the compounds shown in the formula (I) and the formula (II), R is C1-C6 alkyl, and X is F, cl, br or I. In the method, the compound shown in the formula (II) is used as an initial raw material, and the compound and methylhydrazine are subjected to a ring closing reaction with high efficiency, so that side reactions hardly occur, the method has the advantages of high selectivity and yield, and the prepared pyrazole compound (pyrazole herbicide intermediate) is high in purity. In addition, the method provided by the invention has mild reaction conditions, and related reagents are safe and have low cost.
Description
Technical Field
The invention relates to the technical field of herbicide preparation, and particularly relates to a method for preparing a pyrazole compound.
Background
The topramezone is a good-effect herbicide, is the first benzyl ester pyrazolone herbicide developed by basf, belongs to a p-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor, has a good effect of preventing and removing weeds resistant to glyphosate, triazines, acetolactate synthase (ALS) inhibitors and acetyl coenzyme A carboxylase inhibitors, and can prevent and remove main gramineous weeds and broadleaf weeds on corn crops in the world. Therefore, extensive attention is paid to the synthesis of the benzene pyrazole compounds.
The benzene pyrazole compound is generally prepared from an intermediate 1-methyl-5-hydroxypyrazole. CN105218449, IN201611027903, WO2017075910, WO2009069044, CN111440160A and the like disclose a preparation method of 1-methyl-5 hydroxypyrazole, which is mainly prepared by the following two ways:
a：
b：
in the prior art, diethyl malonate or an analogue reacts with triethyl orthoformate or methyl ester and acetic anhydride, and then the diethyl malonate or the analogue reacts with methylhydrazine to close a ring and carry out hydrolysis and decarboxylation to prepare 1-methyl-5 hydroxypyrazole serving as a topramezone intermediate; or diethyl oxaloacetate and methylhydrazine are adopted to close the ring and undergo hydrolysis decarboxylation to prepare the topramezone intermediate 1-methyl-5 hydroxypyrazole. However, these two methods have poor selectivity in the ring closure reaction with methylhydrazine, which results in the production of a large amount of isomer 1-methyl-4 hydroxypyrazole, and have the disadvantages of low yield, strong corrosivity and difficult recovery of acetic anhydride and its by-products in the diethyl malonate process, and large usage of triethyl orthoformate (or methyl ester) and high cost, thus being not suitable for industrial production.
Disclosure of Invention
The invention aims to overcome the technical problems in the prior art and provides a method for preparing pyrazole compounds. The method has the advantages of high selectivity and yield, and the prepared pyrazole compound (pyrazole herbicide intermediate) has high purity.
In order to achieve the above object, the present invention provides a method for preparing a pyrazole compound, comprising: in the presence of a first solvent and a first alkaline substance, carrying out a ring closure reaction on a compound shown as a formula (II) and methylhydrazine to obtain a compound shown as a formula (I); in the compounds shown in the formula (I) and the formula (II), R is C1-C6 alkyl, and X is F, cl, br or I.
Compared with the prior art, the compound shown in the formula (II) is used as a starting material, the ring closure reaction is efficiently carried out with methylhydrazine, and almost no side reaction occurs, so that the selectivity, yield and purity of a target compound are high, and the compound shown in the formula (II) is hydrolyzed and decarboxylated in the presence of acid to obtain the high-purity 1-methyl-5-hydroxypyrazole in high yield. In addition, the method provided by the invention has mild reaction conditions, the related reagents are safe and have lower cost, and part of materials can be recycled, so that the cost is further reduced.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a method for preparing a pyrazole herbicide intermediate, which comprises the following steps: in the presence of a first solvent and a first alkaline substance, carrying out a ring closure reaction on a compound shown as a formula (II) and methylhydrazine to obtain a compound shown as a formula (I); wherein in the compounds shown in the formula (I) and the formula (II), R is C1-C6 alkyl, and X is F, cl, br or I.
According to some embodiments of the invention, in the compounds of formula (I) and formula (II), R is methyl or ethyl and X is Cl or Br.
In the present invention, the compound represented by the formula (II) can be obtained commercially or can be prepared by referring to a conventional manner in the art. For example, the following procedure can be followed (taking the preparation of diethyl 2-chloro-2-butenedioate as an example): mixing diethyl maleate, a second solvent (such as N, N-dimethylformamide) and a second alkaline substance (such as potassium carbonate), heating to 45-60 ℃, introducing chlorine into the system, keeping the temperature at 45-60 ℃ for reaction for 0.5-2h after the chlorine is introduced, and decompressing the reacted system at 70-90 ℃ and 0.05-0.095 MPa to remove the second solvent to obtain the compound shown in the formula (II). Wherein the mol ratio of the diethyl maleate, the second basic substance and the chlorine gas is 1: (1.05-1.2): (1.3-1.8). Preferably, the chlorine gas is passed at a rate of 0.3 to 0.6g/min relative to 0.2mol of diethyl maleate. Preferably, the second solvent is used in an amount of 80 to 120g with respect to 0.2mol of diethyl maleate.
According to some embodiments of the invention, the conditions of the ring closure reaction may comprise: the temperature is-20 deg.C to 100 deg.C (-20 deg.C, -10 deg.C, 0 deg.C, 10 deg.C, 20 deg.C, 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C, 80 deg.C, 90 deg.C, 100 deg.C or any value therebetween), preferably-10 deg.C to 60 deg.C; the time is 1-10h, preferably 4-7h.
According to some embodiments of the present invention, the molar ratio of the compound represented by formula (II), methylhydrazine, and the first basic substance may be 1: (1-1.5): (1.1-2), preferably 1: (1.05-1.2): (1.1-1.3).
According to some embodiments of the present invention, the first basic substance may be selected from one of sodium methoxide, sodium ethoxide, N-diisopropylethylamine, triethylamine, pyridine, sodium carbonate, potassium carbonate, sodium formate, sodium acetate, potassium acetate, N-dimethylaniline, preferably from sodium methoxide and/or potassium carbonate.
According to some embodiments of the present invention, the first solvent may be selected from at least one of C6-C8 alkane, C1-C4 halohydrocarbon, C6-C10 aromatic hydrocarbon, C1-C4 monohydric alcohol, C2-C6 oxacycloalkane and N, N-dimethylformamide, preferably from at least one of cyclohexane, dichloromethane, dichloroethane, toluene, methanol, ethanol, tetrahydrofuran, propylene oxide, 1, 2-butylene oxide and N, N-dimethylformamide, and more preferably from at least one of methanol, cyclohexane and dichloroethane.
According to some embodiments of the present invention, the first solvent may be used in an amount of 0.5 to 10g, preferably 1 to 5g, per gram of the compound of formula (II).
In the present invention, methylhydrazine is preferably present in the form of an aqueous solution; wherein, the concentration of the aqueous solution of the methylhydrazine is preferably 30 to 50wt%.
In the present invention, in order to obtain a better effect, in the step (1), the feeding manner of the compound represented by the formula (II), the first solvent and methylhydrazine is preferably performed as follows: firstly, mixing the compound shown in the formula (II) and a first solvent, heating the obtained mixture to 25-40 ℃, adding a first alkaline substance into the mixture, then adding an aqueous solution (with the concentration of 30-50 wt%) of methylhydrazine into the system, and then carrying out a ring closing reaction by keeping the temperature at 25-40 ℃. Wherein the addition rate of methylhydrazine is 0.1-1mol/h relative to 1mol of the compound represented by the formula (II).
In the present invention, the post-treatment method in the step (1) is not particularly limited as long as the requirements of the present invention can be satisfied. This can be done, for example, by: and (3) decompressing and removing the first solvent from the reacted system at the temperature of less than or equal to 80 ℃ (preferably 30-80 ℃) and the pressure of 0.05MPa-0.095MPa to obtain the compound shown in the formula (I).
According to some embodiments of the invention, the method further comprises the steps of:
hydrolyzing and decarboxylating the compound shown in the formula (I) in the presence of acid to obtain 1-methyl-5-hydroxypyrazole (the compound shown in the formula (III)),
according to some embodiments of the invention, in step (1), the conditions of the ring closure reaction may include: the temperature is-10 ℃ to 60 ℃; the time is 4-7h;
the molar ratio of the compound shown in the formula (II), the methylhydrazine and the first alkaline substance is 1: (1.05-1.2): (1.1-1.3);
the first alkaline substance is selected from sodium methoxide and/or potassium carbonate;
the first solvent is selected from at least one of methanol, cyclohexane and dichloroethane;
the first solvent is used in an amount of 1 to 5g per gram of the compound represented by the formula (II).
According to some embodiments of the invention, in step (2), the conditions of the hydrolytic decarboxylation may comprise: the temperature is 30-150 ℃, preferably 60-140 ℃, and further preferably 60-90 ℃; the time is 1-10h, preferably 4-7h.
According to some embodiments of the invention, the molar ratio of the compound of formula (I) to the acid may be 1: (1-5), preferably 1: (2-3).
According to some embodiments of the invention, the acid is an inorganic acid, preferably selected from at least one of hydrochloric acid, sulfuric acid and hydrobromic acid, more preferably selected from hydrochloric acid and/or sulfuric acid.
According to some embodiments of the invention, the hydrolytic decarboxylation is carried out in the presence of a third solvent selected from at least one of a C6 to C8 alkane, a C1 to C4 halohydrocarbon, a C6 to C10 arene, a C2 to C6 oxacycloalkane, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, and toluene, preferably at least one selected from N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMA), and toluene.
According to some embodiments of the present invention, the third solvent is used in an amount ranging from 0.2 to 10g, preferably from 0.5 to 3g, per gram of the compound of formula (I).
In the present invention, the post-treatment of step (2) is not particularly limited as long as the requirements of the present invention can be satisfied. For example, reference may be made to the following: removing the third solvent from the reacted system, adding an organic solvent (preferably C1-C4 alcohol such as ethanol), pulping, and filtering to obtain a filter cake; the product (1-methyl-5-hydroxypyrazole) is obtained. The amount of the organic solvent used for the beating is not particularly limited, and preferably, the amount of the organic solvent used may be 0.5 to 3g relative to 1g of the compound represented by the formula (I).
The present invention will be described in detail below by way of examples.
In the following examples, the raw materials, solvents, bases and the like used were all obtained commercially without specific description; the progress of the reaction and the product purity were monitored by HPLC (high performance liquid chromatography); the yield was calculated from the actual product molar weight/theoretical product molar weight x 100%.
Example 1
In this example, X = Cl and R = Et
(1) 41.2g (0.2 mol) of a compound represented by the formula (II) (diethyl 2-chloro-2-butenedioate) and 100g of methanol were sequentially added to a 250mL four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and after the temperature was raised to 30 ℃, 11.88g (0.22 mol) of sodium methoxide was added, 25.3g (0.22mol, 40wt%) of an aqueous solution of methylhydrazine was added dropwise to the above system, and after the dropwise addition was completed within 3 hours, a ring-closing reaction was carried out by keeping the temperature at 30 ℃ for 4 hours, the reaction was monitored by HPLC to be complete, and methanol was removed under reduced pressure at 50 ℃ and 0.07MPa to obtain a compound represented by the formula (I), the purity was 99 wt%, and the yield was 98%.
(2) 50g of DMF and 56g of sulfuric acid (70 wt%,0.4 mol) are added into the compound shown in the formula (I) obtained above, the temperature is raised to 60 ℃ for hydrolysis and decarboxylation reaction for 8h, after DMF is removed, 40g of ethanol is added into a system after the reaction for pulping and filtration, and filter cake 1-methyl-5-hydroxypyrazole is obtained, the purity is 96 wt%, and the yield is 95%.
Example 2
In this example, X = Cl and R = Et
(1) 41.2g (0.2 mol) of diethyl 2-chloro-2-butenedioate and 100g of dichloromethane were sequentially added to a 250mL four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and after the temperature was raised to 30 ℃ and 30.36g (0.22 mol) of potassium carbonate was added thereto, 24.15g (0.21mol, 40wt%) of an aqueous solution of methylhydrazine was added dropwise to the above system, and after the addition was completed within 3 hours, the ring-closing reaction was carried out at 30 ℃ for 4 hours, the reaction was monitored by HPLC to be complete, and the dichloromethane was removed under reduced pressure at 30 ℃ and 0.05MPa to obtain the compound represented by the formula (I), the purity was 98.5 wt%, and the yield was 97.5%.
(2) Adding 50g of DMF and 56g of sulfuric acid (70 wt%,0.4 mol) into the compound shown in the formula (I) obtained above, heating to 70 ℃ to perform hydrolysis and decarboxylation reaction for 8 hours, removing DMF, adding 40g of ethanol into the reacted system, pulping and filtering to obtain the filter cake 1-methyl-5-hydroxypyrazole with the purity of 95.5 wt% and the yield of 94%.
Example 3
In this example, X = Cl and R = Et
(1) 41.2g (0.2 mol) of diethyl 2-chloro-2-butenedioate and 100g of tetrahydrofuran were sequentially added to a 250mL four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and after the temperature was raised to 30 ℃ and 30.36g (0.22 mol) of potassium carbonate was added thereto, 25.3g (0.22mol, 40wt%) of an aqueous solution of methylhydrazine was added dropwise to the system, the reaction was allowed to stand at 30 ℃ for 4 hours, HPLC was carried out to monitor completion of the reaction, and tetrahydrofuran was removed under reduced pressure at 60 ℃ and 0.075MPa to obtain the compound represented by formula (I), wherein the purity was 99% by weight and the yield was 98%.
(2) 50g of toluene and 56g of sulfuric acid (70 wt%,0.4 mol) are added into the compound shown in the formula (I) obtained above, the temperature is raised to 80 ℃ for hydrolysis and decarboxylation reaction for 8h, after toluene is removed, 40g of ethanol is added into the reacted system for pulping and filtration, and the filter cake 1-methyl-5-hydroxypyrazole with the purity of 96.5 wt% and the yield of 96% is obtained.
Example 4
In the present example, X = Cl, R = Et
41.2g (0.2 mol) of the compound represented by the formula (II) (diethyl 2-chloro-2-butenedioate) and 100g of toluene were sequentially added to a 250mL four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and after the temperature was raised to 100 ℃, 11.88g (0.22 mol) of sodium methoxide was added thereto, 25.3g (0.22mol, 40wt%) of an aqueous solution of methylhydrazine was added dropwise to the above system, and after the dropwise addition was completed within 3 hours, a ring-closing reaction was carried out by keeping the temperature at 100 ℃ for 4 hours, the reaction was monitored by HPLC to be complete, and toluene was removed under reduced pressure at 80 ℃ and 0.095MPa to obtain the compound represented by the formula (I), which had a purity of 80% by weight and a yield of 78%.
Example 5
The procedure is as in example 1, except that the temperature of the ring closure reaction is varied to-20 ℃.
In the present example, X = Cl, R = Et
(1) 41.2g (0.2 mol) of the compound represented by the formula (II) (diethyl 2-chloro-2-butenedioate) and 100g of methanol were sequentially added to a 250mL four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and after cooling to-20 ℃ a mixture of 11.88g (0.22 mol) of sodium methoxide was added thereto, 25.3g (0.22mol, 40wt%) of an aqueous solution of methylhydrazine was added dropwise to the above system, and after completion of the dropwise addition, a ring-closing reaction was carried out at-20 ℃ for 4 hours, HPLC was carried out to monitor completion of the reaction, and methanol was removed under reduced pressure at 50 ℃ and 0.07MPa to obtain the compound represented by the formula (I) with a purity of 95 wt% and a yield of 90%.
Example 6
In this example, X = Cl and R = Et
The procedure of example 1 was followed, except that the compound represented by the formula (II), the first solvent, the first basic substance and methylhydrazine were added simultaneously during the ring-closing reaction, and methylhydrazine (aqueous solution of methylhydrazine) was not added dropwise.
(1) 41.2g (0.2 mol) of the compound represented by the formula (II) (diethyl 2-chloro-2-butenedioate), 100g of methanol and 25.3g (0.22mol, 40wt%) of an aqueous solution of methylhydrazine were simultaneously charged into a 250mL four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and subjected to a ring-closing reaction at 30 ℃ for 4 hours, HPLC monitoring for completion of the reaction, and methanol was removed under reduced pressure at 50 ℃ and 0.07MPa to give the compound represented by the formula (I) in a purity of 92% by weight and a yield of 87%.
Comparative example 1
The 1-methyl-5-hydroxypyrazole is prepared by referring to the existing method, and the preparation method comprises the following specific steps:
adding 0.2mol of diethyl malonate compound, 0.6mol of acetic anhydride and 0.48mol of triethyl orthoformate into a 500mL four-mouth bottle provided with a mechanical stirrer, a thermometer and a condenser, heating to 125 ℃, carrying out reflux reaction for 2h, then reducing the reflux temperature to 104 ℃, and controlling the content of diethyl malonate to be less than 1% in gas chromatography (the ratio of the peak area of diethyl malonate is less than 1%). The acetic acid mixed solution is evaporated under reduced pressure to 110 ℃, the temperature is reduced to 10 ℃, and 120g of anhydrous methanol is added. Stirring and controlling the reaction temperature to be 10 ℃, dropwise adding an aqueous solution (0.33mol, 40wt%) of methylhydrazine, reacting for 4 hours at 25 ℃ after 2 hours of addition, removing methanol under reduced pressure, adding sulfuric acid (0.2mol, 70wt%) and 120g of N, N-dimethylformamide, heating to 85 ℃ for hydrolysis and decarboxylation for 7 hours, removing a solvent, adding 40g of ethanol, pulping, filtering, and refining to obtain the benzene pyrazole herbicide intermediate (1-methyl-5-hydroxypyrazole).
By detection and calculation, the purity of the 1-methyl-5-hydroxypyrazole was 93 wt%, and the yield was 71%.
In the comparative example, in the ring closing reaction, the isomer 1-methyl-4 hydroxypyrazole is generated, the influence on the yield is large, acetic anhydride is used in the method, a large amount of acetic acid byproducts are generated, and the acetic acid byproducts are difficult to treat and environment-friendly.
Comparative example 2
The 1-methyl-5-hydroxypyrazole is prepared by the prior method, and the method comprises the following specific steps:
56.4g (0.3 mol) of diethyl oxaloacetate and 150g of ethanol are added into a 500mL four-neck flask provided with a mechanical stirring device, a thermometer and a condenser tube, 37.95g (0.33mol, 40wt%) of a methylhydrazine aqueous solution is dropwise added at 25 ℃, heat preservation stirring is carried out after the dropwise addition is finished, ring closing is carried out for 5 hours, the ethanol is evaporated under reduced pressure, 84g (0.6 mol, 70wt%) of sulfuric acid and 120g of N, N-dimethylacetamide are added, the temperature is increased to 70 ℃, hydrolysis and decarboxylation are carried out for 5 hours, 30g of ethanol is added after the solvent is removed, pulping and filtering are carried out, and the 1-methyl-5-hydroxypyrazole is prepared.
Through detection and calculation, the purity of the obtained phenylpyrazole intermediate (1-methyl-5-hydroxypyrazole) is 92% by weight, and the yield is 74%.
Compared with the existing method, the method provided by the invention can obtain the pyrazole herbicide intermediate with higher purity and yield, and in a preferred embodiment, the purity of the pyrazole herbicide intermediate prepared by the method can reach more than 95 weight percent, and the yield can reach more than 93 percent. In addition, as can be seen from the above examples, the method of the present invention has the advantages of safety, simplicity and low cost.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including various technical features being combined in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A process for preparing a pyrazole compound, comprising: in the presence of a first solvent and a first alkaline substance, carrying out a ring closure reaction on a compound shown in a formula (II) and methylhydrazine to obtain a compound shown in a formula (I); wherein in the compounds shown in the formula (I) and the formula (II), R is C1-C6 alkyl, and X is F, cl, br or I;
2. the method according to claim 1, wherein in the compounds of formula (I) and formula (II), R is methyl or ethyl, and X is Cl or Br.
3. The method of claim 1 or 2, wherein the conditions of the ring closure reaction comprise: the temperature is-20 ℃ to 100 ℃, preferably-10 ℃ to 60 ℃; the time is 1-10h, preferably 4-7h.
4. The method according to any one of claims 1 to 3, wherein the compound represented by formula (II), methylhydrazine, and the first basic substance are present in a molar ratio of 1: (1-1.5): (1.1-2), preferably 1: (1.05-1.2): (1.1-1.3).
5. The process according to any one of claims 1 to 4, wherein the first basic substance is selected from one of sodium methoxide, sodium ethoxide, N-diisopropylethylamine, triethylamine, pyridine, sodium carbonate, potassium carbonate, sodium formate, sodium acetate, potassium acetate, N-dimethylaniline, preferably from sodium methoxide and/or potassium carbonate.
6. The process according to any one of claims 1 to 5, wherein the first solvent is selected from at least one of C6-C8 alkanes, C1-C4 halogenated hydrocarbons, C6-C10 aromatic hydrocarbons, C1-C4 monohydric alcohols, C2-C6 oxacycloalkanes, and N, N-dimethylformamide, preferably from at least one of cyclohexane, dichloromethane, dichloroethane, toluene, methanol, ethanol, tetrahydrofuran, propylene oxide, 1, 2-butylene oxide, and N, N-dimethylformamide, more preferably from at least one of methanol, cyclohexane, dichloroethane;
and/or the first solvent is used in an amount of 0.5 to 10g, preferably 1 to 5g, per gram of the compound of formula (II).
7. The method of any of claims 1-6, wherein the method further comprises: in the presence of acid, the compound shown in the formula (I) is subjected to hydrolytic decarboxylation to obtain the 1-methyl-5-hydroxypyrazole.
8. The method of claim 7, wherein in step (1), the conditions of the ring closure reaction comprise: the temperature is-10 ℃ to 60 ℃; the time is 4-7h;
the molar ratio of the compound represented by the formula (II), methylhydrazine and the first basic substance is 1: (1.05-1.2): (1.1-1.3);
the first alkaline substance is selected from sodium methoxide and/or potassium carbonate;
the first solvent is selected from at least one of methanol, cyclohexane and dichloroethane;
the first solvent is used in an amount of 1 to 5g per gram of the compound represented by the formula (II).
9. A process according to claim 7 or 8, wherein the conditions of the hydrolytic decarboxylation comprise: the temperature is 30-150 ℃, preferably 60-140 ℃; the time is 1-10h, preferably 4-7h.
10. The process according to any one of claims 7 to 9, wherein the molar ratio of the compound of formula (I) to the acid is 1: (1-5), preferably 1: (2-3);
and/or the acid is an inorganic acid, preferably at least one selected from hydrochloric acid, sulfuric acid and hydrobromic acid, more preferably selected from hydrochloric acid and/or sulfuric acid;
and/or the hydrolytic decarboxylation is carried out in the presence of a third solvent selected from at least one of C6-C8 alkanes, C1-C4 halogenated hydrocarbons, C6-C10 aromatic hydrocarbons, C2-C6 oxacycloalkanes, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone and toluene, preferably at least one selected from N, N-dimethylformamide, N-dimethylacetamide and toluene;
preferably, the third solvent is used in an amount of 0.2 to 10g, preferably 0.5 to 3g, per gram of the compound of formula (I).
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