A method for preparing trans-ambrobinic acid

Abstract

The application discloses a preparation method of trans-cuparemic acid, which comprises the following steps: step one, crushing and mixing; step two, extracting by heating and refluxing with ethyl acetate; step three, secondary extraction; step four, reducing pressure concentration; step five, elution treatment; and step six, concentration and recrystallization; wherein in the step one, cupressaceae plants are dried and crushed, and then screened; subsequently, the screened cupressaceae plant powder is uniformly mixed with equal amount of calcium carbonate powder to obtain mixed powder, which is prepared for use; in the step two, appropriate mixed powder obtained in the step one is weighed, and a certain amount of ethyl acetate is added to obtain a mixture; subsequently, the obtained mixture is boiled by heating for 2 hours, and a first extraction liquid is obtained by filtering; the application can effectively avoid pigment interference, and only one column chromatography operation is needed in the separation process; the obtained trans-cuparemic acid has large yield and high purity, and can be produced on a large scale.

Description

Technical Field

[0001] This invention relates to the field of trans-pigmentic acid preparation technology, specifically a method for preparing trans-pigmentic acid. Background Technology

[0002] Trans-communic acid is a white crystalline solid with the molecular formula C2. 20 H 30 O2, with a molecular weight of 302, is a diterpenoid compound. Currently, trans-piperidine acid has been added to high-end cosmetics in monomeric or extract form, with positive market response; literature also reports that this compound possesses various beneficial effects, including anticancer, antibacterial, and anti-inflammatory properties. This component is widely distributed in cypress family plants, such as the fruit of Mediterranean cypress (Cupressus sempervirens) and European juniper (Juniperus communis). However, current processes result in low extraction rates of trans-piperidine acid, and the separation methods are cumbersome, requiring multiple column chromatography, gel chromatography, and high-performance liquid chromatography processes to finally obtain the monomeric compound, leading to high costs and low efficiency in production. Therefore, finding a plant rich in trans-piperidine acid and an abundant plant resource, and optimizing a new method for preparing high-purity trans-piperidine acid from its extract, has become a crucial issue that urgently needs to be addressed.

[0003] Domestic and international scholars have conducted extensive research on the preparation of trans-pigmentic acid. Zhao Qinshi et al. first isolated trans-pigmentic acid from the leaf extract of *Platycladus orientalis* (Fujian cypress). Their method, using 95% ethanol cold maceration followed by ethyl acetate extraction, silica gel column chromatography elution, and recrystallization, yielded a final yield of 0.76%. However, the leaves of this plant exhibited significant pigment interference during the extraction process. While the cold maceration method used by Zhao Qinshi et al. effectively minimizes pigment interference in the early stages of extraction, it results in a low yield, requiring multiple extractions (≥3 times), leading to a long production time and high solvent consumption. International researchers have employed solvent-based rapid extraction methods initially, followed by multiple column chromatography separations to improve the purity of the trans-pigmentic acid product. However, this process is complex, costly, and difficult to scale up. Therefore, designing a proper preparation method for trans-pigmentic acid is essential. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing trans-piperic acid, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing trans-cadal acid, comprising the following steps: Step 1, pulverizing and mixing; Step 2, ethyl acetate extraction under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization; In step one above, cypress plant material is taken, dried, pulverized, and then screened. The screened cypress plant material powder is then mixed evenly with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. In step two above, an appropriate amount of the mixed powder obtained in step one is weighed out and a certain amount of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours and filtered to obtain a primary extract. In step three above, the filter residue obtained from step two is added to an equal amount of ethyl acetate from step two, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain an extract paste. In step five above, PRP macroporous adsorption resin column chromatography elution: the elution solvent is an ethanol-water system; first, 60%-65% ethanol is used to elute and remove impurities, eluting for 3-5 column volumes; then, 75%-85% ethanol is used to elute for 5-6 column volumes, the eluent is collected, and concentrated under reduced pressure to obtain a high concentration of trans-pinenic acid extract. In step six above, the high-concentration trans-pinenic acid extract obtained in step five is first taken, and a mixture of ethyl acetate and acetone is added. The mixture is heated until the extract is completely dissolved to form a supersaturated solution. The solution is then naturally cooled to room temperature, and white solid crystals precipitate out. After filtration and drying, high-purity trans-pinenic acid is obtained.

[0006] Preferably, in step one, the selected sieve mesh size is 20 mesh.

[0007] Preferably, in step one, the plant body, especially the roots, branches, leaves, fruits, and mixtures thereof, are from the Cupressaceae family, particularly the European juniper (J. communis) and the Fujian juniper (F. hodginsii).

[0008] Preferably, in step two, the mass ratio of the mixed powder to ethyl acetate is 1:5.

[0009] Preferably, in step two, the weighing device used has an accuracy of 0.1 ml.

[0010] Preferably, in step six, the crystallization solvent is a mixture of ethyl acetate and acetone, with a volume ratio ranging from 0.5 to 0.75.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: the preparation method of trans-pillar acid does not require multiple column chromatography, gel chromatography and liquid chromatography separations, the extraction method is simpler, the cost is low, the efficiency is high, and the product yield can reach 0.18-0.27%, which is 20%-80% higher than the original maximum yield of 0.15%. Moreover, the invention can effectively avoid pigment interference, the separation process only requires one column chromatography operation, and the obtained trans-pillar acid has a large yield and high purity, which can be used for large-scale production. Attached Figure Description

[0012] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is the chemical structural diagram of trans-piperic acid. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Please see Figure 1-2 One embodiment provided by the present invention: Example 1: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is the leaves of Fujian cypress. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 52.2g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 52g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1L of 65% ethanol solution is used to remove impurities, followed by 1.5L of 80% ethanol solution. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-piperic acid extract. In step six above, ethyl acetate and acetone were mixed in a 2:3 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 1.92 g of trans-picolinic acid was obtained.

[0015] Example 2: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material powder obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is European juniper leaves. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 52.2g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 52g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1 L of 65% ethanol solution is used to remove impurities, and then 1.5 L of 80% ethanol solution is used to elute. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone were mixed in a 2:3 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.32 g of trans-picolinic acid was obtained.

[0016] Example 3: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material powder obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is the root of European juniper. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 52.2g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 52g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1 L of 65% ethanol solution is used to remove impurities, and then 1.5 L of 80% ethanol solution is used to elute. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone were mixed in a 2:3 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.71 g of trans-picolinic acid was obtained.

[0017] Example 4: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is the branches and leaves of Fujian cypress. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 52.2g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 52g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1L of 65% ethanol solution is used to remove impurities, followed by 1.5L of 80% ethanol solution. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-piperic acid extract. In step six above, ethyl acetate and acetone were mixed in a 2:3 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.08 g of trans-picolinic acid was obtained.

[0018] Example 5: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is European juniper branches and leaves. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 52.2g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 52g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1 L of 65% ethanol solution is used to remove impurities, and then 1.5 L of 80% ethanol solution is used to elute. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, a 2:3 mixture of ethyl acetate and acetone was heated to form a supersaturated solution. After being allowed to cool naturally at room temperature, white needle-like crystals precipitated. These crystals were filtered and dried to obtain 2.46 g of trans-pillar acid. Example 6: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is Fujian cypress branch. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 52.2g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 52g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1 L of 65% ethanol solution is used to remove impurities, and then 1.5 L of 80% ethanol solution is used to elute. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone were mixed in a 2:3 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.16 g of trans-picolinic acid was obtained.

[0019] Example 7: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is the leaves of Fujian cypress. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 54.6g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 55g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1L of 60% ethanol solution is used to remove impurities, followed by 1.5L of 75% ethanol solution. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone were mixed in a 1:2 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 1.76 g of trans-pillar acid was obtained.

[0020] Example 8: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material powder obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is European juniper leaves. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 54.6g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 55g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1L of 60% ethanol solution is used to remove impurities, followed by 1.5L of 75% ethanol solution. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone are mixed in a 1:2 ratio and heated to form a supersaturated solution. The solution is allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.01 g of trans-pillar acid is obtained.

[0021] Example 9: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material powder obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is European juniper leaves. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 63.1g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 63g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1L of 60% ethanol solution is used to remove impurities, followed by 1.5L of 75% ethanol solution. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone were mixed in a 3:4 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.11 g of trans-pillar acid was obtained.

[0022] Example 10: A method for preparing trans-pyridinic acid includes the following steps: Step 1, pulverizing and mixing; Step 2, extraction with ethyl acetate under reflux; Step 3, secondary extraction; Step 4, concentration under reduced pressure; Step 5, elution treatment; Step 6, concentration and recrystallization. In step one above, cypress plant material is taken, dried and pulverized, and then screened with a sieve mesh size of 20. The cypress plant material powder obtained by screening is then mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is the root of European juniper. In step two above, 1000g of the mixed powder obtained in step one is weighed and 10000ml of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours, filtered to obtain a primary extract, and the accuracy of the weighing device used is 0.1ml. In step three above, the filter residue obtained from step two is added to 10,000 ml of ethyl acetate, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain 63.1g of extract paste. In step five above, the extract from step four is dissolved in ethyl acetate and mixed with 63g of PRP-512A macroporous adsorption resin. The mixture is then eluted by column chromatography using PRP-512A macroporous adsorption resin. First, 1L of 60% ethanol solution is used to remove impurities, followed by 1.5L of 75% ethanol solution. The eluent is collected, and the solvent is recovered under reduced pressure until dry to obtain a high-concentration trans-pinenic acid extract. In step six above, ethyl acetate and acetone were mixed in a 3:4 ratio and heated to form a supersaturated solution. The solution was allowed to cool naturally at room temperature, resulting in the precipitation of white needle-like crystals. After filtration and drying, 2.52 g of trans-picolinic acid was obtained.

[0023] The yield and purity of trans-cyperric acid obtained in the above examples were calculated, and the results are shown in the table below: The spectroscopic characteristics of trans-cadal acid obtained in Example 1 above are as follows: ESI-MS m / z : 303[M+H] + ; 1 H-NMR (400 MHz, CDCl3): δ 6.33(1H,dd, J =17.2,10.4Hz, H-14), 5.41 (1H,t, J = 6.8Hz, H-12), 5.04(1H,d, J =17.2Hz, H-15a), 4.88(1H, d, J =10.8Hz, H-15b), 4.84 (1H, s, H-17a), 4.46 (1H, s, H-17b), 1.75 (3H, s, H-16), 1.25 (3H, s, H-18), 0.65 (3H, s, H-20); 13 C-NMR (100MHz, CDCl3): δ 183.8(C-19),148.0(C-8),141.7(C-14), 134.1(C-12), 133.6(C-13),110.1(C-15), 107.8(C-17), 56.5(C-9), 56.4(C-5),44.3(C-4),40.5(C-10),39.4(C-1),38.6(C-7),38.0(C-3),29.2(C-18), 26.0(C-6), 23.4(C-11),20.0(C-2), 13.0(C-20),12.0(C-16).

[0024] Based on the above, the advantages of this invention are that the plant material is pulverized, mixed with an equal amount of calcium carbonate powder, extracted by heating and reflux with ethyl acetate, eluted with PRP macroporous adsorption resin, recrystallized, filtered, and dried to obtain white solid crystals, which are trans-pinenic acid. This method can effectively avoid pigment interference, the separation process only requires one column chromatography operation, and the obtained trans-pinenic acid has a large yield and high purity, which can be used for large-scale production.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing trans-cadal acid, comprising the following steps: Step 1: Crushing and mixing; Step 2: Extraction with ethyl acetate under reflux; Step 3: Secondary extraction; Step 4: Concentration under reduced pressure; Step 5: Elution; Step 6: Concentration and recrystallization; Characterized by: In step one above, cypress plant material is taken, dried, pulverized, and then screened. The screened cypress plant material powder is then uniformly mixed with an equal amount of calcium carbonate powder to obtain a mixed powder for later use. The cypress plant material is selected from the roots, branches, leaves, fruits, and mixtures of European juniper and Fujian cypress. In step two above, an appropriate amount of the mixed powder obtained in step one is weighed out and a certain amount of ethyl acetate is added to obtain a mixture. The mixture is then heated and boiled for 2 hours and filtered to obtain a primary extract. In step three above, the filter residue obtained from step two is added to an equal amount of ethyl acetate from step two, heated and boiled again for 2 hours, and filtered to obtain a secondary extract. The secondary extract is then mixed with the primary extract obtained from step two to obtain a combined extract. In step four above, the combined extract obtained in step three is concentrated under reduced pressure to obtain an extract paste. In step five above, the PRP-512A macroporous adsorption resin column chromatography elution uses an ethanol-water system as the elution solvent. First, 60%-65% ethanol is used to elute and remove impurities, eluting for 3-5 column volumes. Then, 75%-85% ethanol is used to elute for 5-6 column volumes. The eluent is collected and concentrated under reduced pressure to obtain a high-concentration trans-pinenic acid extract. In step six above, the high-concentration trans-pinenic acid extract obtained in step five is first taken, and a crystallization solvent is added. The crystallization solvent is a mixture of ethyl acetate and acetone. The mixture is heated until the extract is completely dissolved to form a supersaturated solution. The solution is then naturally cooled to room temperature, and white solid crystals precipitate out. After filtration and drying, high-purity trans-pinenic acid is obtained.

2. The method for preparing trans-cadal acid according to claim 1, characterized in that: In step one, the selected sieve mesh size is 20 mesh.

3. The method for preparing trans-cadal acid according to claim 1, characterized in that: In step two, the mass ratio of the mixed powder to ethyl acetate is 1:

5.

4. The method for preparing trans-cadal acid according to claim 1, characterized in that: In step two, the weighing equipment used has an accuracy of 0.1 ml.

5. The method for preparing trans-cadal acid according to claim 1, characterized in that: In step six, the crystallization solvent is a mixture of ethyl acetate and acetone, with a volume ratio ranging from 0.5 to 0.75.

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