New process for synthesizing isolongifolanone

Abstract

The invention relates to the technical field of organic matter synthesis, in particular to a novel process for synthesizing isolongifolanone, which comprises the following steps: pouring phosphorus pentoxide, phosphoric acid and acetic acid into a reaction kettle, heating to a preset temperature, and mixing and stirring; slowly adding longifolene into the reaction kettle under the conditions of maintaining constant temperature and stirring, carrying out isomerization reaction, and separating to obtain an isolongifolene mixed solution; and connecting the ozone gas washing bottle with an ozone generator, continuously introducing ozone to promote the oxidation reaction of isolongifolene, and separating to obtain an isolongifolanone mixed solution. Phosphorus pentoxide, phosphoric acid and acetic acid are used as catalysts for isomerism of longifolene, the states of the catalysts are changed through the proper proportion of the phosphorus pentoxide, the phosphoric acid and the acetic acid to form polyphosphoric acid, the polyphosphoric acid and isolongifolene are not dissolved mutually, generation of separation waste water is greatly reduced, the separated polyphosphoric acid can be continuously used only by adding a small amount of consumptions, and the production cost is reduced. And the raw material cost and the separation cost of isomerization are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a new process for synthesizing isolongifolanone. Background Art

[0002] Isolongifolanone, with the chemical formula C15H24O, is a colorless or yellow liquid. The relative density is about 0.997 - 1.010, the refractive index is 1.498 - 1.503, the flash point is 106 °C, and it is soluble in ethanol. It has a strong aroma, with fresh woody fragrance, and very similar to the woody fragrance and soil fragrance of natural patchouli. It is suitable for use in woody fragrance types, can give woody fragrance, and can be coordinated with other woody fragrance spices; it can give top note when used in perfume essence; it can also be coordinated in the compound of many fragrance types, and the aroma is relatively persistent.

[0003] For the synthesis of isolongifolanone, such as the Chinese invention patents with the patent publication numbers CN108358764A and CN113511963A, which disclose the synthesis methods of isolongifolanone. A large amount of formic acid and sulfuric acid are required as catalysts for the isomerization reaction of the raw material longifolene. Sulfuric acid and formic acid will be miscible with longifolene, resulting in a large amount of alkali solution for alkali washing and neutralization after synthesizing isolongifolanone, with a large amount of wastewater discharge; moreover, the usage amounts of the formic acid and sulfuric acid mixture are both large and difficult to recycle, and the isomerization cost is high; and the amount of hydrogen peroxide used in the oxidation process is also large, and there is a certain danger in large - batch storage, and safety accidents are prone to occur.

[0004] Therefore, according to the above - mentioned related technologies, it is urgent to develop a new process for synthesizing isolongifolanone that can not only reduce the preparation cost but also avoid the potential safety hazards of raw material storage. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to propose a new process for synthesizing isolongifolanone to solve the problems of high cost of isomerization using formic acid and sulfuric acid as catalysts and potential safety hazards in the storage of oxidation raw materials in the prior art.

[0006] Based on the above purpose, the present invention provides a new process for synthesizing isolongifolanone, including the following steps:

[0007] Pour phosphorus pentoxide, phosphoric acid and acetic acid into a reaction kettle, heat to a predetermined temperature and mix and stir.

[0008] Under the conditions of maintaining a constant temperature and stirring, slowly add longifolene to the reaction kettle for isomerization reaction, and separate to obtain a mixture of isolongifolene.

[0009] Connect an ozone washing bottle to an ozone generator, continuously introduce ozone to promote the oxidation reaction of isolongifolene, and separate to obtain a mixture of isolongifolanone.

[0010] Sodium carbonate solution is added to isolongifolione to neutralize the residual acidic substances. After the neutralization reaction is completed, deionized water is added for washing until the solution is neutral.

[0011] 15 - 20 grams of phosphorus pentoxide, 25 - 30 grams of phosphoric acid, and 50 - 60 grams of acetic acid are used.

[0012] 328 grams of longifolene is added.

[0013] The ozone concentration is adjusted to 50 - 250 mg / L, and ozone is continuously introduced for 3 - 15 hours. The ozone introduction time is inversely proportional to the ozone concentration.

[0014] Preferably, these chemicals are gradually added to a reaction kettle equipped with a mechanical stirrer and a temperature control system. The stirrer is started to reach 300 - 400 r / min, and the mixture is slowly heated to a predetermined temperature of 50 - 60 °C.

[0015] Ensure uniform mixing to prepare the required polyphosphoric acid mixture. During this process, the temperature and stirring speed in the reaction kettle need to be strictly controlled to avoid local overheating and reaction runaway.

[0016] Preferably, under the conditions of maintaining a constant temperature and stirring, longifolene is slowly added to the reaction kettle through an accurate dropping device.

[0017] During the entire dropping process, keep the temperature and stirring speed in the reaction kettle stable to ensure that longifolene is in full contact with the polyphosphoric acid mixture and undergoes isomerization reaction.

[0018] Preferably, in the isomerization reaction stage, after dropping all the longifolene, the reaction continues at a temperature range of 50 - 60 °C for 3 hours.

[0019] During this period, samples are taken regularly, and the isomerization degree of longifolene is monitored by gas chromatography analysis technology to determine whether the reaction reaches the expected effect.

[0020] Preferably, after the isomerization reaction is completed, the mixture containing the isomerization product is carefully transferred to a separating funnel and left to stand for 1 hour to allow the polyphosphoric acid and the organic phase to fully separate.

[0021] A total of 100 g of phosphorus pentoxide, phosphoric acid, and acetic acid are added. Approximately 90 grams of polyphosphoric acid can be separated out, replenished to 100 g according to the feeding ratio, and stored properly for reuse in subsequent experiments. The organic phase is the isolongifolene mixture.

[0022] Preferably, for the separated isolongifolene mixture, 300 grams of deionized water is added, and after thorough mixing, it is transferred to a pre - prepared ozone washing bottle.

[0023] Preferably, the temperature is controlled within the range of 25°C - 30°C. The specific model of the ozone generator is GCY-T-250. After the oxidation reaction of isolongifolene is completed, the ozone supply is stopped, and the oxidized mixture is sampled. The degree of oxidation is confirmed by gas chromatography analysis.

[0024] Preferably, the oxidized mixture is transferred back to the separating funnel again. Using the liquid separation technique, the isolongifolanone mixture and the aqueous waste are quickly separated. Then, 100 grams of 10% sodium carbonate solution is added to the isolongifolanone mixture, and 100 grams of deionized water is added for washing.

[0025] Approximately 340 grams of aqueous waste can be collected and discarded. For isolongifolanone, approximately 310 grams are collected to neutralize the residual acidic substances. After the neutralization reaction is completed, this step needs to be repeated until it reaches neutrality to ensure the purity and quality of isolongifolanone.

[0026] Advantages of the present invention:

[0027] The present invention provides a new process for synthesizing isolongifolanone. Phosphorus pentoxide, phosphoric acid, and acetic acid are used as catalysts to isomerize isolongifolene. By appropriately mixing the three, the state of the catalyst is changed to form polyphosphoric acid. Polyphosphoric acid is immiscible with isolongifolanone, while formic acid and sulfuric acid can dissolve in isolongifolanone. The layering is obvious and separation can be achieved without water washing, greatly reducing the generation of separation wastewater. The separated polyphosphoric acid can be reused by adding only a small amount of consumables, reducing the raw material cost and separation cost of isomerization;

[0028] In the present invention, ozone is used to oxidize isolongifolene into isolongifolanone. It is transferred to an ozone washing bottle, and ozone is prepared immediately at room temperature. Ozone is used as the oxidant for the oxidation reaction of isolongifolene, avoiding the safety hazard of storing a large amount of hydrogen peroxide. The solubility of ozone in the isolongifolene mixture under normal pressure is low. By pressurizing and injecting ozone during the reaction stage, the oxidation rate can be ensured, and the amount of alkali solution required to neutralize the slightly dissolved ozone after the oxidation reaction is greatly reduced, reducing the neutralization cost and difficulty after oxidation. Specific embodiments

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0030] The sources and properties of some raw materials used in the present invention are as follows:

[0031] Acetic acid was purchased from Jining Bocheng Chemical Co., Ltd.; phosphorus pentoxide was purchased from Shandong Xiju Biotechnology Co., Ltd.; phosphoric acid was purchased from Henan Anno Chemical Technology Co., Ltd.; sulfuric acid was purchased from Longbai Group Co., Ltd.; hydrogen peroxide was purchased from Binzhou Chemical Industry Group Co., Ltd.; sodium hydroxide was purchased from Tianjin Chengyuan Chemical Co., Ltd.; longifolene was purchased from Guangdong Tianlong Fine Chemical Co., Ltd.

[0032] Example 1: A new process for synthesizing isolongifolione, comprising the following steps:

[0033] S1. Preparation of polyphosphoric acid mixture

[0034] Under the guidance of laboratory safety operating procedures, accurately weigh 20 g of phosphorus pentoxide, 30 g of phosphoric acid, and 50 g of acetic acid. Gradually add these chemicals into a reaction kettle equipped with a mechanical stirrer and a temperature control system. Start the stirrer and slowly heat to the predetermined temperature of 55°C to ensure uniform mixing, thereby preparing the required polyphosphoric acid mixture. During this process, strictly control the temperature and stirring speed in the reaction kettle to avoid local overheating and reaction runaway.

[0035] S2. Isomerization reaction

[0036] Under the conditions of maintaining a constant temperature and stirring, slowly add 328 g of longifolene into the reaction kettle through an accurate dropping device. During the entire dropping process, keep the temperature and stirring speed in the reaction kettle stable to ensure sufficient contact between longifolene and the polyphosphoric acid mixture and the occurrence of isomerization reaction. After the dropping is completed, continue to react at 55°C for 3 hours. During this period, take samples regularly and monitor the isomerization degree of longifolene by gas chromatography analysis technology to determine whether the reaction reaches the expected effect.

[0037] S3. Preparation for oxidation reaction

[0038] After the reaction is completed, carefully transfer the mixture containing the isomerization product to a separatory funnel and let it stand for 1 hour to allow the polyphosphoric acid to fully separate from the organic phase. Subsequently, separate 92 g of polyphosphoric acid, replenish it to 100 g according to the feeding ratio, and store it properly for reuse in subsequent experiments. For the separated organic phase, add 300 g of deionized water to it, mix well, and transfer it to a pre-prepared ozone washing bottle.

[0039] S4. Ozone oxidation

[0040] Within the environmental temperature control range (25°C - 30°C), connect the ozone washing bottle to the ozone generator. The ozone generator was purchased from Hebei Guanyu Environmental Protection Equipment Co., Ltd., with the specific model GCY-T-250. Adjust the ozone concentration to 250 mg / L and continuously introduce ozone for 3 hours to promote the oxidation reaction of isolongifolene. After the reaction ends, stop the ozone supply and take samples of the oxidized mixture, and confirm the degree of oxidation through gas chromatography analysis;

[0041] S5. Post-treatment

[0042] Transfer the oxidized mixture back to the separating funnel again, and quickly separate the aqueous phase and the organic phase using the liquid separation technique. Collect 340 grams of the aqueous phase and discard it. For the organic phase, namely isolongifolanone, collect 310 grams, and add 100 grams of 10% sodium carbonate solution to neutralize the residual acidic substances. After the neutralization reaction is completed, add 100 grams of deionized water for washing until the solution is neutral. This step needs to be repeated until it reaches neutrality to ensure the purity and quality of isolongifolanone.

[0043] Example 2: A new process for synthesizing isolongifolanone, including the following steps:

[0044] S1. Prepare the polyphosphoric acid mixture

[0045] Under the guidance of laboratory safety operating procedures, accurately weigh 15 grams of phosphorus pentoxide, 25 grams of phosphoric acid, and 60 grams of acetic acid. Gradually add these chemicals to the reaction kettle equipped with a mechanical stirrer and a temperature control system. Start the stirrer and slowly heat to the predetermined temperature of 60°C to ensure uniform mixing, thereby preparing the required polyphosphoric acid mixture. During this process, strictly control the temperature and stirring speed in the reaction kettle to avoid local overheating and reaction out of control;

[0046] S2. Isomerization reaction

[0047] Under the condition of maintaining a constant temperature and stirring, slowly add 328 grams of longifolene to the reaction kettle through a precise dropping device. During the entire dropping process, keep the temperature and stirring speed in the reaction kettle stable to ensure that longifolene and the polyphosphoric acid mixture are in full contact and undergo an isomerization reaction. After the dropping is completed, continue to react at 60°C for 3 hours. During this period, take samples regularly and monitor the isomerization degree of longifolene through gas chromatography analysis technology to determine whether the reaction reaches the expected effect;

[0048] S3. Oxidation reaction preparation

[0049] After the reaction is completed, carefully transfer the mixed solution containing the isomerization product to a separatory funnel and let it stand for 1 hour to allow the polyphosphoric acid to fully separate from the organic phase. Subsequently, separate 88 grams of polyphosphoric acid, replenish it to 100 grams according to the feeding ratio, and store it properly for reuse in subsequent experiments. For the separated organic phase, add 300 grams of deionized water to it, mix well, and transfer it to a pre-prepared ozone scrubber bottle;

[0050] S4. Ozone Oxidation

[0051] Within the ambient temperature control range (25°C - 30°C), connect the ozone scrubber bottle to an ozone generator purchased from Hebei Guanyu Environmental Protection Equipment Co., Ltd., with the specific model GCY-T-250. Adjust the ozone concentration to 50 mg / L and continuously introduce ozone for 15 hours to promote the oxidation reaction of isolongifolene. After the reaction is completed, stop the ozone supply and take a sample of the oxidized mixed solution to confirm the degree of oxidation through gas chromatography analysis;

[0052] S5. Post-treatment

[0053] Transfer the oxidized mixed solution back to a separatory funnel again, and quickly separate the aqueous phase and the organic phase using the liquid separation technique. Collect 338 grams of the aqueous phase and discard it. For the organic phase, namely isolongifolanone, collect 312 grams and add 100 grams of 10% sodium carbonate solution to neutralize the residual acidic substances. After the neutralization reaction is completed, add 100 grams of deionized water for washing until the solution is neutral. This step needs to be repeated until it reaches neutrality to ensure the purity and quality of isolongifolanone.

[0054] Example 3: A new process for synthesizing isolongifolanone, comprising the following steps:

[0055] S1. Preparation of polyphosphoric acid mixed solution

[0056] Under the guidance of laboratory safety operating procedures, accurately weigh 18 grams of phosphorus pentoxide, 27 grams of phosphoric acid, and 55 grams of acetic acid. Gradually add these chemicals to a reaction kettle equipped with a mechanical stirrer and a temperature control system. Start the stirrer and slowly heat to the predetermined temperature of 50°C to ensure uniform mixing, thereby preparing the required polyphosphoric acid mixed solution. During this process, strictly control the temperature and stirring speed in the reaction kettle to avoid local overheating and reaction runaway;

[0057] S2. Isomerization reaction

[0058] Under the conditions of maintaining a constant temperature and stirring, 328 grams of longifolene were slowly added to the reaction kettle through an accurate dropping device. During the entire dropping process, the temperature and stirring speed inside the reaction kettle were kept stable to ensure that the longifolene and polyphosphoric acid mixture were in full contact and underwent an isomerization reaction. After the dropping was completed, the reaction continued at 50 °C for 3 hours. During this period, samples were taken regularly, and the isomerization degree of longifolene was monitored by gas chromatography analysis technology to determine whether the reaction achieved the expected effect;

[0059] S3. Preparation for oxidation reaction

[0060] After the reaction was completed, the mixture containing the isomerization product was carefully transferred to a separating funnel and allowed to stand for 1 hour to enable the polyphosphoric acid and the organic phase to be fully separated. Subsequently, 90 grams of polyphosphoric acid were separated out, replenished to 100 g according to the feeding ratio, and properly stored for reuse in subsequent experiments. For the separated organic phase, 300 grams of deionized water were added thereto, and after thorough mixing, it was transferred to a pre-prepared ozone washing bottle;

[0061] S4. Ozone oxidation

[0062] Within the environmental temperature control range (25 °C - 30 °C), the ozone washing bottle was connected to an ozone generator purchased from Hebei Guanyu Environmental Protection Equipment Co., Ltd., with the specific model being GCY-T-250. The ozone concentration was adjusted to 150 mg / L, and ozone was continuously introduced for 5 hours to promote the oxidation reaction of isolongifolene. After the reaction ended, the ozone supply was stopped, and a sample of the oxidized mixture was taken, and the oxidation degree was confirmed by gas chromatography analysis;

[0063] S5. Post-treatment

[0064] The oxidized mixture was transferred to a separating funnel again, and the aqueous phase and the organic phase were quickly separated by liquid separation technology. 341 grams of the aqueous phase were collected and discarded. For the organic phase, namely isolongifolanone, 309 grams were collected, and 100 grams of 10% sodium carbonate solution were added thereto to neutralize the residual acidic substances. After the neutralization reaction was completed, 100 grams of deionized water were added for washing until the solution was neutral. This step was repeated until neutrality was achieved to ensure the purity and quality of isolongifolanone.

[0065] Comparative Example 1:

[0066] In this comparative example, compared with Example 1, only "phosphorus pentoxide" was replaced with "an equal amount of phosphoric acid", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0067] Comparative Example 2:

[0068] In this comparative example, compared with Example 1, only "phosphorus pentoxide" was replaced with "an equal amount of acetic acid", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0069] Comparative Example 3:

[0070] In this comparative example, compared with Example 1, only "phosphoric acid" was replaced with "an equal amount of acetic acid", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0071] Comparative Example 4:

[0072] In this comparative example, compared with Example 1, only "phosphoric acid" was replaced with "an equal amount of phosphorus pentoxide", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0073] Comparative Example 5:

[0074] In this comparative example, compared with Example 1, only "acetic acid" was replaced with "an equal amount of phosphoric acid", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0075] Comparative Example 6:

[0076] In this comparative example, compared with Example 1, only "acetic acid" was replaced with "an equal amount of phosphorus pentoxide", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0077] Comparative Example 7:

[0078] In this comparative example, compared with Example 1, only "phosphorus pentoxide, phosphoric acid, and acetic acid were mixed evenly in a mass ratio of 2:3:5" was replaced with "phosphorus pentoxide, phosphoric acid, and acetic acid were mixed evenly in a mass ratio of 1:1:1", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0079] Comparative Example 8:

[0080] In this comparative example, compared with Example 1, only "phosphorus pentoxide, phosphoric acid, and acetic acid were mixed evenly in a mass ratio of 2:3:5" was replaced with "phosphorus pentoxide, phosphoric acid, and acetic acid were mixed evenly in a mass ratio of 5:3:2", and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally a new process for synthesizing isolongifolanone was obtained.

[0081] Comparative Example 9 (traditional method):

[0082] 1.1 Isomerization step

[0083] Under laboratory conditions, accurately weigh 328 grams of longifolene, and prepare a mixed solution of 350 grams of acetic acid and 30 grams of sulfuric acid as the reaction medium. Under the conditions of mechanical stirring and heating, slowly drop longifolene into the mixed solution of acetic acid and sulfuric acid, while strictly controlling the reaction temperature within the range of 90°C ± 5°C. After the addition of longifolene is completed, continue to maintain this temperature for the reaction. The total reaction time is 5 hours. During the reaction process, regularly take samples for gas chromatography analysis to monitor the isomerization degree of longifolene and ensure that the reaction proceeds completely;

[0084] 1.2 Oxidation step

[0085] After the isomerization reaction is completed, carefully transfer the reaction mixture to a water bath and cool it to 45°C ± 5°C. At this temperature, slowly and evenly drop 150 grams of 30% hydrogen peroxide, and complete the whole process within 3 hours. After the addition of hydrogen peroxide is completed, continue to maintain it in the water bath for 1 hour to complete the oxidation reaction. After the reaction is completed, take samples for gas chromatography analysis to verify the purity and conversion rate of the oxidation product;

[0086] 1.3 Post-treatment step

[0087] Transfer the oxidized mixture to a separating funnel. Since the mixture is in a miscible state, direct liquid separation is not feasible. Considering that isolongifolanone is insoluble in water, sulfuric acid, acetic acid, hydrogen peroxide, etc., and the above solvents can all be mixed with water, add 500 grams of deionized water to the mixture, shake well to promote the separation of isolongifolanone from other mixtures. After liquid separation operation, about 1030 grams of waste liquid is separated, and about 305 grams of isolongifolanone is collected. Subsequently, add 200 grams of 10% sodium carbonate solution to isolongifolanone to neutralize the residual acidic substances. After the neutralization reaction is completed, add 200 grams of deionized water for washing until isolongifolanone is neutral to complete the final post-treatment step. During this process, the operating conditions should be strictly controlled to ensure the purity and quality of the product.

[0088] The isomerization yield of longifolene by this method is about 78%, and the isolongifolanone yield is about 82%. For every 100 g of isolongifolanone (content 61%) obtained, about 460 g of wastewater is generated, 116 g of acetic acid is consumed, 10 g of sulfuric acid is consumed, and 50 g of hydrogen peroxide is consumed.

[0089] Performance test:

[0090] Catalyst performance:

[0091] Referring to the national standard of China's "GB / T 20940-2007", 5.0 g of the polyphosphoric acid mixed solutions prepared in Examples 1-3 and Comparative Examples 1-8 were weighed respectively. Refractive index, viscosity and molecular weight are important parameters of the properties of polyphosphoric acid, which can be used to evaluate its purity and degree of polymerization. The following are the measurement methods and required equipment for these parameters:

[0092] Refractive index measurement: Refractive index is an optical property of a substance, which can be used to indirectly judge the degree of polymerization of polyphosphoric acid.

[0093] Measurement method:

[0094] Measure using an Abbe refractometer or an automatic refractometer. Place the polyphosphoric acid sample in the measuring chamber of the refractometer, adjust the refractometer to refract the light passing through the sample, and read the refractive index.

[0095] Required equipment:

[0096] Abbe refractometer or automatic refractometer, clean sample container, thermometer (because the refractive index varies with temperature).

[0097] Viscosity measurement: Viscosity is the ability of a fluid to resist flow, and it has a direct relationship with the degree of polymerization.

[0098] Measurement method:

[0099] Measure using a rotational viscometer or a capillary viscometer. Place the polyphosphoric acid sample in the measuring container of the viscometer and measure the viscosity of the sample at a constant temperature.

[0100] Required equipment:

[0101] Rotational viscometer or capillary viscometer, temperature control device (such as a water bath), clean sample container.

[0102] Molecular weight measurement: Gel Permeation Chromatography GPC. GPC is a technique used to determine the molecular weight distribution of high molecular compounds.

[0103] Measurement method:

[0104] Prepare a GPC system, including a chromatographic column, a detector and a data recording device. Dissolve the polyphosphoric acid sample in an appropriate solvent, inject it through the GPC system, record the time for the eluent to pass through the chromatographic column, and use the calibration curve of the standard sample to determine the molecular weight.

[0105] Required equipment:

[0106] GPC system (including a pump, a chromatographic column, a detector, a data processor), standard sample (polymer with known molecular weight), solvent (such as tetrahydrofuran THF or other solvents suitable for polyphosphoric acid), injector.

[0107] When conducting these measurements, it should be noted that:

[0108] All measurements should be carried out under controlled temperature conditions because temperature affects refractive index and viscosity; to ensure accuracy, the instrument should be calibrated using standard samples; appropriate safety measures should be taken during operation because polyphosphoric acid is corrosive; the detailed operating procedures and execution standards for these measurement methods can be found in relevant scientific literature, instrument operation manuals, or international standards (such as ISO, ASTM). Before conducting these experiments, it is recommended to carefully read and understand these guidelines, and determine the purity and degree of polymerization of the polyphosphoric acid mixed solutions prepared in Examples 1 - 3 and Comparative Examples 1 - 8;

[0109] Oxidation performance:

[0110] Respectively, for the oxidation degree during the preparation of isolongifolanone in Examples 1 - 3 and Comparative Examples 1 - 8. In the experiment of preparing isolongifolanone, gas chromatography is a commonly used analytical technique that can be used to confirm the oxidation degree. The following are the basic steps, execution standards, and required equipment for confirming the oxidation degree through gas chromatography analysis:

[0111] Analysis steps:

[0112] Sample preparation:

[0113] Dissolve a quantitative sample of isolongifolanone in a suitable solvent. If necessary, the sample can be converted into a derivative that is easier to analyze through a derivatization reaction.

[0114] Chromatographic condition setting:

[0115] Select a suitable chromatographic column, such as a capillary column, whose stationary phase is usually non-polar or weakly polar and is suitable for analyzing isolongifolanone and its oxidation products; determine chromatographic parameters such as column temperature, injector temperature, detector temperature, etc.; set the flow rate of the carrier gas (such as helium or nitrogen);

[0116] Injection and analysis:

[0117] Use a microsyringe to inject the prepared sample into the gas chromatograph; run the instrument and record the chromatogram;

[0118] Result analysis:

[0119] By comparing the sample chromatogram with the chromatogram of the standard product, determine the types and relative contents of the oxidation products; use peak area or peak height for quantitative analysis;

[0120] Execution standards:

[0121] The standard for analyzing flavors and fragrances by gas chromatography is ASTM D3612; the standard for determining flavors and fragrances by gas chromatography is ISO 12228; the official analytical method standard in the food and agriculture fields is AOAC International.

[0122] Required equipment:

[0123] Gas chromatograph: equipped with an injection port, chromatographic column, detector (such as FID, TCD or MSD) and data recording system; Chromatographic column: a capillary column suitable for analyzing isolongifolione and its oxidation products; Detector: the most commonly used is the flame ionization detector (FID), but other types can also be used, such as the mass spectrometry detector (MSD); Carrier gas supply system: providing carrier gases such as helium or nitrogen; Microsyringe: for accurate sample injection; Sample preparation tools: such as vortex mixer, centrifuge, balance, etc.; Standards: isolongifolione and its oxidation products with known purity.

[0124] When performing gas chromatography analysis, the following best practices should be ensured: Calibrate using appropriate standards to establish a calibration curve; Ensure that the gas chromatograph operates under optimal conditions and perform maintenance and calibration if necessary; Keep the laboratory environment stable, especially temperature and humidity, as they can affect chromatographic results; Take appropriate safety measures as harmful chemicals may be involved in the operation; Through the above steps and equipment, the oxidation degree of isolongifolione can be effectively confirmed by gas chromatography analysis.

[0125] Table 1 Summary of experimental data in Examples 1 - 3 and Comparative Examples 1 - 8

[0126]

[0127]

[0128]

[0129] Data analysis:

[0130] As can be seen from Table 1, the process for preparing isolongifolione of the present invention has better isomerization cost, oxidation cost and raw material safety. In summary, the isomerization yield of longifolene by the method is about 78.5%, and the yield of isolongifolione is about 85%. For every 100 g of isolongifolione (content 64%) obtained, in Comparative Example 9, using the traditional method, there are significant disadvantages both in terms of the output of the target product and the consumption of intermediates. It can be seen that in the isomerization stage, by adjusting the ratio of different catalysts, the yield of isomerization products can be increased. In the oxidation stage, by changing the oxide to gaseous ozone, it can be quickly separated after oxidation and can also reduce the effect of increasing isomerization products;

[0131] It should be emphasized that in Examples 1 - 3 and Comparative Examples 7 - 8, before isomerization, due to the optimized ratio of the catalyst, polymerization of phosphoric acid occurred to obtain a polyphosphoric acid mixture. After the isomerization reaction, compared with traditional formic acid, sulfuric acid, etc. which are miscible with isolongifolene, isolongifolene can be separated by layering with polyphosphoric acid after standing. After the oxidation reaction, ozone can be prepared instantaneously during the reaction without the need for large - scale storage, and ozone will not dissolve in large amounts in the mixed solution after the oxidation reaction. There is no need for a large amount of alkali solution to neutralize the unreacted acidic catalyst, nor a large amount of clean water for washing. Overall, for every 100 g of isolongifolanone (content 64%) obtained, only about 166 g of wastewater is generated, consuming 5 - 6 g of acetic acid, 1.5 - 2 g of phosphorus pentoxide, and 2.5 - 3 g of phosphoric acid. This significantly reduces the separation difficulty of isolongifolene in the isomerization reaction stage, reduces the consumption of neutralizing materials in the oxidation reaction stage, and also solves the storage safety problem of oxidation reaction intermediates;

[0132] In Comparative Examples 1 and 2, since "phosphorus pentoxide" was replaced with "an equal amount of phosphoric acid" or "an equal amount of acetic acid", as can be seen from Table 1, although phosphoric acid can be used as a catalyst for the isomerization reaction, keeping the isomerization reaction and products in a relatively good range, however, only heating phosphoric acid and acetic acid for polymerization reaction cannot produce polyphosphoric acid. After isomerization, there will be separately existing acetic acid and phosphoric acid dissolved in the isolongifolene solution, causing difficulties in separating the product and the catalyst and increasing the neutralization cost;

[0133] In Comparative Examples 3 and 4, since "phosphoric acid" was replaced with "an equal amount of phosphorus pentoxide" or "an equal amount of acetic acid", as can be seen from Table 1, although phosphorus pentoxide and acetic acid can be used as catalysts for the isomerization reaction, the isomerization reaction and products are kept in a relatively low range, the isomerization catalytic effect is not good, and at the same time, there is also the problem that polyphosphoric acid cannot be produced, affecting the subsequent separation and neutralization;

[0134] In Comparative Examples 5 and 6, since "acetic acid" was replaced with "an equal amount of phosphorus pentoxide" or "an equal amount of phosphoric acid", as can be seen from Table 1, the catalytic effect of the isomerization reaction of this mixture is relatively good. However, in specific experiments, because acetic acid was not added, the preparation time of polyphosphoric acid is longer, the required temperature is higher, and after the isomerization reaction, the preparation of polyphosphoric acid needs to be carried out frequently. This may be because there is no acetic acid as a catalyst for polyphosphoric acid preparation and a consumable for the isomerization reaction, resulting in a long preparation time of polyphosphoric acid and a large consumption of polyphosphoric acid in the isomerization reaction, which will indirectly lead to a reduction in preparation efficiency;

[0135] In Comparative Example 7, since "phosphorus pentoxide, phosphoric acid, and acetic acid are mixed evenly in a mass ratio of 2:3:5" is replaced with "phosphorus pentoxide, phosphoric acid, and acetic acid are mixed evenly in a mass ratio of 1:1:1", it can be seen from Table 1 that its isomerization performance is poor. This may be because the content of acetic acid decreases, and the consumption in the isomerization reaction decreases, resulting in a decrease in the yield of isolongifolene per unit time;

[0136] In Comparative Example 8, since "phosphorus pentoxide, phosphoric acid, and acetic acid are mixed evenly in a mass ratio of 2:3:5" is replaced with "phosphorus pentoxide, phosphoric acid, and acetic acid are mixed evenly in a mass ratio of 5:3:2", it can be seen from Table 1 that its isomerization performance is poor. This may be because the proportion of phosphorus pentoxide in this catalyst is too high, resulting in excessive waste, and the content of acetic acid, which is mainly the consumption in the isomerization reaction, is too small.

[0137] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

[0138] The present invention aims to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omission, modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A new process for synthesizing isothiocarbazanone, characterized in that: The following steps are involved: Pour phosphorus pentoxide, phosphoric acid and acetic acid into a reaction kettle, heat to a predetermined temperature and mix and stir; Under the condition of maintaining a constant temperature and stirring, slowly adding longifolene into the reactor to carry out an isomerization reaction, and separating to obtain an isolongifolene mixed liquid; The ozone washing bottle is connected to the ozone generator, and ozone is continuously introduced to promote the oxidation reaction of isolongifolene, and the isolongifole ketone mixed liquid is separated; Adding sodium carbonate solution to isolongifolia alkane to neutralize the residual acidic substances, and after the neutralization reaction is completed, adding deionized water for washing until the solution is neutral; 15-20 g of phosphorus pentoxide, 25-30 g of phosphoric acid, and 50-60 g of acetic acid; Add 328 g of longifolene; The ozone concentration is adjusted to 50-250 mg / L, and ozone is continuously introduced for 3-15 hours. The ozone introduction time is inversely proportional to the ozone concentration.

2. The novel process for synthesizing isothiocarbanone according to claim 1, characterized in that: These chemicals are gradually added into a reactor equipped with a mechanical stirrer and a temperature control system, the stirrer is started to reach 300-400r / min, and slowly heated to a predetermined temperature of 50-60°C.

3. The novel process for synthesizing isolongifolia alkone according to claim 2, characterized in that: While maintaining constant temperature and stirring conditions, longifolene was slowly added to the reactor through a precise drop-feeding device.

4. The novel process for synthesizing isothiocarbanone according to claim 3, characterized in that: In the isomerization reaction stage, after the longifolene is added dropwise, the reaction is continued for 3 hours at a temperature range of 50-60°C.

5. The novel process for synthesizing isothiocarbazanone according to claim 1, characterized in that: After the isomerization reaction was completed, the mixed solution containing the isomerization product was carefully transferred to a separatory funnel and allowed to stand for 1 hour to allow the polyphosphoric acid and the organic phase to be fully separated.

6. The novel process for synthesizing isothiocarbanone according to claim 5, characterized in that: For the separated isolongifolene mixed solution, 300 g of deionized water was added thereto, mixed thoroughly, and then transferred to a pre-prepared ozone washing bottle.

7. The novel process for synthesizing isolongifolia alkone according to claim 6, characterized in that: The oxidized mixed solution is transferred to the separatory funnel again, and the isolongifolia alkane mixed solution and the aqueous phase waste are quickly separated by using the separation technology.

8. The novel process for synthesizing isolongifolia alkone according to claim 7, characterized in that: 100 g of 10% sodium carbonate solution was added to the isolongifolia alkane mixed solution, and then 100 g of deionized water was added for washing.

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