A process for the preparation of cashmerone

Abstract

The application provides a preparation method of costunolide, and the preparation method comprises the following steps: in the presence of an oxygen source, 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is subjected to an oxidation reaction under the catalysis of a boride catalyst to obtain costunolide. The preparation method has the advantages of high yield, no pollution, low energy consumption, high safety, simple operation and good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis of musk-type fragrances, and particularly relates to a method for preparing cashmereone. Background Technology

[0002] Cashmeran, also known as indanone, has the chemical name 1,1,2,3,3-pentamethyl-6,7-dihydro-4H-indanone. It appears as a pale yellow liquid with a melting point of 27°C. At room temperature, it is sometimes a crystalline solid. It has a strong, long-lasting, and sweet musky and woody aroma, with floral and ambergris notes. It is a raw material for the formulation of fragrances in high-end perfumes and cosmetics.

[0003] Industrially, cashmereone is mostly produced using 1,1,2,3,3-pentamethylindane (abbreviated as pentamethylindane) as a raw material. Raney nickel is used as a catalyst to selectively hydrogenate tetrahydropentamethylindane, which is then oxidized to obtain cashmereone.

[0004] IFF's patent US3876562A first reported the synthetic route of cashmereone, using pentamethylindane as a raw material, Raney nickel as a catalyst, and a hydrogenation reaction at 1000 psi pressure and 150-185°C, followed by oxidation with potassium dichromate to obtain cashmereone, with a yield of 40-45%. However, this method suffers from problems such as high hydrogen pressure and high reaction temperature, demanding equipment requirements, significant safety risks, and high energy consumption. Furthermore, the disposal of chromium-containing waste is difficult, posing significant environmental pressure, and there is considerable room for improvement in the reaction yield.

[0005] CN113929564A discloses a synthetic route for cashmiphene, in which the oxidation method uses oxygen, air, or a mixture of air and oxygen in any proportion as the oxygen source, a composite catalyst composed of ferric nitrate and N-hydroxyphthalimide (NHPI), and a solvent, and obtains the product through multiple post-processing steps. The main problems with this method are: (1) The use of a solvent in the oxidation reaction increases the risk of combustion and explosion, resulting in low safety. (2) Water is produced during the oxidation process, and a certain water content will cause the reaction to quench. (3) Ferric nitrate is acidic after dissolving in water, which can easily cause equipment corrosion. In addition, toxic gases such as nitric oxide and nitrogen dioxide are produced during the reaction, which are harmful to human health and the environment.

[0006] Current oxidation processes for cashmere often use chromium-containing oxidants, ultimately producing chromium salt waste that causes serious environmental pollution, especially to water bodies. Later optimizations, such as using chromium-containing oxidants in acetic acid to prepare cashmere, still fail to solve the chromium salt pollution problem.

[0007] In industrial production, the oxidation of cashmiphene typically involves two steps: First, sodium (potassium) dichromate is used as an oxidant to produce a mixture of cashmiol and cashmiphene; second, cobalt acetate / glacial acetic acid is used as a catalytic system to further oxidize the cashmiphene. This method yields 50-55% of the product. Both steps utilize chromium-containing oxidants, generating environmentally polluting chromium salts. The equations for the two-step oxidation reactions are as follows:

[0008]

[0009] In summary, the oxidation process of cashmereone suffers from problems such as low yield, environmental pollution, high energy consumption, and complex post-processing. Therefore, developing a cashmereone production process that is high-yield, pollution-free, low-energy-consumption, highly safe, and simple to operate is a key research focus in this field. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing cashmereone. This method offers high yield, is pollution-free, low-energy-consumption, highly safe, and simple to operate, demonstrating promising prospects for industrial application.

[0011] To achieve this objective, the present invention adopts the following technical solution:

[0012] On one hand, the present invention provides a method for preparing cashmereone, the method comprising the following steps:

[0013] In the presence of an oxygen source, 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane undergoes an oxidation reaction catalyzed by a boride catalyst to yield cashmereone.

[0014] This invention discloses a method for preparing cashmereone by catalyzing the oxidation of tetrahydropentamethylindene in the presence of oxygen using boride as a catalyst. After the reaction, the catalyst is easily separated and can be recycled multiple times. This invention reduces the two-step oxidation reaction to a single step, and does not use solvents during the reaction. The post-processing is simple and eliminates the need for energy-intensive solvent recovery, greatly simplifying the cashmereone production process and reducing production costs.

[0015] Preferably, the boride is selected from one or a combination of at least two of manganese boride (MnB), nickel boride (NiB), nickel boride (Ni2B), iron boride (FeB), ferric boride (Fe2B), chromium boride (CrB), chromium diboride (CrB2), cobalt boride (CoB), cobalt diboride (Co2B), cobalt triboride (Co3B), cobalt diboride (CoB2), vanadium boride (VB2), titanium boride (TiB2), or copper boride (Cu3B2); preferably, it is a mixture of at least two of cobalt boride (CoB), cobalt diboride (Co2B), or cobalt triboride (Co3B).

[0016] In this invention, the boride can be prepared using existing methods. Common methods include the one-step stenothermal method used in the synthesis of nanocrystalline cobalt boride and its catalytic method for efficient hydrogen production from ammonia borane, as described by Jin Zhikang et al. Another common method involves reacting a metal (e.g., cobalt) with boron at high temperature, typically in a hydrogen atmosphere. Alternatively, the boride can be prepared using a sodium borohydride reduction method. This involves dissolving a metal salt in water and sodium borohydride in alkaline water to form a solution, which is then added dropwise to the salt solution for reduction, yielding a mixture or a single substance, depending on the amount of sodium borohydride used. Adding phase transfer catalysts and organic compounds can also help form dispersions with smaller pore sizes.

[0017] Specifically, the following preparation methods can be used to prepare borides:

[0018] Metal oxides or hydroxides, sodium borohydride, hexadecyltrimethylammonium bromide, and NMP (N-methylpyrrolidone) are added to a high-pressure reactor in a molar ratio of 1:1.25:0.2:3. Nitrogen gas is introduced three times to purge the reactor. The reaction is carried out at 1.5-2.0 MPa and 800℃ for 12 hours. The product is calcined in a muffle furnace at 400-600℃ for 6 hours. The obtained product is thoroughly washed three times with deionized water and ethanol, vacuum dried for 12 hours, and then pulverized to 100-200 mesh to obtain the catalyst product.

[0019] Preferably, the purity of the 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene is 10%-100%, for example 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, and specific values ​​between the above values ​​are not exhaustively listed in this invention for space limitations and for the sake of brevity; preferably 45.0%-80.0%.

[0020] When the purity of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane in the raw materials described in this invention is not 100%, the other components it contains are at least one of the following: a full-hydrogen product (2-5% by weight), a dihydrogen product (2-5% by weight), or pentamethylindane (10-50% by weight). The water content in the 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane raw materials described in this invention is ≤0.1% by weight, and it does not contain any other solvents.

[0021] Preferably, the amount of catalyst used is 0.1%-20% of the full mass of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene, for example 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 10%, 12%, 14%, 16%, 18% or 20%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 3.0%-5.0%.

[0022] Preferably, the oxygen source is pure oxygen, air, or a gas containing any concentration of oxygen.

[0023] Preferably, the temperature of the oxidation reaction is 5-250℃, for example 5℃, 10℃, 15℃, 20℃, 50℃, 80℃, 100℃, 130℃, 150℃, 180℃, 200℃, 220℃, 240℃ or 250℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 70-100℃ is preferred.

[0024] Preferably, the oxidation reaction is carried out at a pressure of 0 MPa-10.0 MPa, for example 0 MPa, 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 0.8-1.2 MPa.

[0025] Preferably, the oxidation reaction takes 6-9 hours, for example, 6 hours, 7 hours, 8 hours or 9 hours.

[0026] In this invention, after the oxidation reaction is completed, the reaction solution is subjected to vacuum distillation and vacuum rectification to obtain cashmereone.

[0027] Tetrahydropentamethylindene is adsorbed onto M 2+ At the B2 center, a chemisorption complex is formed, first through M 2+ The oxygen vacancy in B2 is associated with the adsorbate complex and M. 3+ B₂O₂ is associated with lattice oxygen, resulting in a partially oxidized product, which is produced by the adjacent M... 3+ B2O2 transfers a lattice oxygen to M. 2+ The B2 center compensates for the lost oxygen, while at M 3+ Electrons generated at the B2O center are transferred to the substrate pentamethylindane. The α-H on the tetrahydropentamethylindane on the catalyst surface is converted by M... 3+B2O attack forms the allyl intermediate of tetrahydropentamethylindenyl, releasing an electron and assuming a positively charged transition state, M. 3+ B2O price decreases M 2+ B2, then with M 3+ B2O2 reacts to form M 3+ The valence state of B2O allows for an infinite repetition of reduction-oxidation, propelling the reaction forward. The allyl intermediate in the transition state combines with lattice oxygen on the catalyst surface to form cashmereone. The removed hydrogen reacts with lattice oxygen to form water (H2O content ≥ 5.0%, reaction quenched). M represents the metal element participating in the catalytic process; its valence state is related to the element type, as described above, the reaction mechanism is as follows... Figure 1 As shown.

[0028] As a preferred embodiment of the present invention, the method for preparing cashmereone specifically includes the following steps:

[0029] In the presence of an oxygen source, 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is oxidized for 6-9 h at 5-250 °C and 0-10.0 MPa under the catalysis of a boride catalyst to obtain cashmereone.

[0030] The oxygen source is pure oxygen, air, or a gas containing oxygen of any concentration. The boride is selected from one or a combination of at least two of manganese boride, nickel boride, nickel boride, iron boride, ferric boride, chromium boride, chromium diboride, cobalt boride, cobalt diboride, cobalt triboride, cobalt diboride, vanadium boride, titanium boride, or copper boride. The purity of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is 10%-100%, and the amount of catalyst used is 0.1%-20% of the mass of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention uses borides as catalysts, which do not produce harmful gases during the reaction process and have less environmental pollution. Since the catalyst is magnetic, it can be efficiently and simply recovered with the help of an external magnetic field after the reaction is completed, which further simplifies the operation process. Moreover, borides can be used as alloy materials, which do not corrode the reactor and have a high safety factor.

[0033] (2) The present invention uses borides as catalysts, and no solvent is needed in the reaction. After the reaction is completed, only distillation and purification are required, and the operation process is simple. The reaction system does not contain solvents, and the risk of combustion and explosion during the reaction and treatment is reduced accordingly, thus improving safety.

[0034] (3) The present invention uses boron metal compounds as catalysts, which significantly improves the utilization rate of reactants. The conversion rate of cashmereone at the end of the reaction is as high as 100%, the selectivity is ≥90.0%, and the yield of cashmereone product is ≥90.0%. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the reaction mechanism for the preparation of cashmereone according to the present invention.

[0036] Figure 2 Mass spectra of cashmereone standard and cashmereone product prepared in Example 12. Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0038] The specific reactants for this invention are obtained by referring to the synthesis method of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane disclosed in patent CN107522583B.

[0039] At room temperature, 500 g of 1,1,2,3,3-pentamethylindene, 500 g of heptane, and 25.0 g of 5% Pd / C (catalyst concentration of 5%) were added to a 1.0 L autoclave. After stirring, the mixture was purged with nitrogen three times, and hydrogen gas was introduced at 4.0 MPa while maintaining the hydrogen pressure at 3.0 MPa. The reaction mixture was kept at 150 °C for 8 hours until the hydrogen pressure no longer decreased. The catalyst was removed by filtration, the solvent was removed by vacuum distillation, and the mixture was then separated by high-efficiency distillation column, maintaining a vacuum of 20-80 Pa, a top temperature of 50-60 °C, and a reactor temperature of 120-130 °C to obtain tetrahydropentamethylindene, with a purity of 99.99% as determined by gas chromatography.

[0040] By mixing the above-mentioned 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane and 1,1,2,3,3-pentamethylindane in different proportions, the raw materials of different purities used in this invention can be obtained.

[0041] 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane with a purity of 10%: Take 1g of 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane and 9g of 1,1,2,3,3-Pentamethylindane to prepare a 10% pure 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane raw material for later use.

[0042] 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane with a purity of 55%: Take 5.5g of 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane and 4.5g of 1,1,2,3,3-Pentamethylindane to prepare a 55% pure 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane raw material for later use.

[0043] 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane with a purity of 60%: Take 6g of 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane and 4g of 1,1,2,3,3-Pentamethylindane to prepare a 60% pure 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane raw material for later use.

[0044] 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane with a purity of 70%: Take 7g of 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane and 3g of 1,1,2,3,3-Pentamethylindane to prepare a 70% pure 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane raw material for later use.

[0045] 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane with a purity of 75%: Take 7.5g of 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane and 2.5g of 1,1,2,3,3-Pentamethylindane to prepare a 10% 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane raw material for later use.

[0046] 90% purity 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane: Take 9g of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane and 1g of 1,1,2,3,3-pentamethylindane to prepare 90% purity 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane raw material for later use.

[0047] 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane with a purity of 97.3%: Take 9.73g of 1,1,2,3,3-Pentamethyl-4,5,6,7-Tetrahydroindane and 0.7g of 1,1,2,3,3-Pentamethylindane to prepare a raw material with a purity of 97.3%, for later use.

[0048] Gas chromatography-mass spectrometry system: Agilent 8890 chromatography workstation;

[0049] Chromatographic column: DB-17, 30m × Φ320μm × 0.25μm; vaporization chamber temperature: 250℃; detection chamber temperature: 300℃; split ratio: 30:1; carrier gas flow rate: 1mL / min; pressure: 7.3327Psi;

[0050] Column oven temperature: 100℃ for 5 minutes, then increase the temperature to 150℃ at a rate of 10℃ / min and hold for 8 minutes, then increase the temperature to 200℃ at a rate of 30℃ / min and hold for 7 minutes.

[0051] Example 1

[0052] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0053] 300g of 10% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co₂B / Co₃B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 70℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 9.3%, the conversion rate was 100%, and the selectivity was 93.0%. 28.9g of crude cashmereone was obtained by vacuum distillation, and 27.0g of the final product with a cashmereone content of 98.2% was obtained by vacuum fractionation, with a yield of 82.5%.

[0054] Example 2

[0055] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0056] 300g of 55% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co2B / Co3B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The reaction was carried out at 5°C and 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 53.9%, the conversion rate was 45.6%, and the selectivity was 98.1%. Vacuum distillation yielded 74.3g of crude cashmereone, and vacuum fractionation yielded 72.2g of the finished product with a cashmereone content of 99.1%, with a yield of 97.0%.

[0057] Example 3

[0058] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0059] 300g of 90% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co2B / Co3B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 70℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone content was 87.2%, the conversion rate was 100%, and the selectivity was 96.9%. 285.6g of crude cashmereone was obtained by vacuum distillation, and 281.4g of a finished product with a cashmereone content of 99.1% was obtained by vacuum fractionation, yielding a yield of 96.3%.

[0060] Example 4

[0061] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0062] 300g of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene (97.3% purity) was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co₂B / Co₃B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 70°C and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 94.9%, the conversion rate was 100%, and the selectivity was 97.5%. Vacuum distillation yielded 301.2g of crude cashmereone, and vacuum fractionation yielded 297.1g of the final product with a cashmereone content of 99.0%, a yield of 94.1%.

[0063] Example 5

[0064] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0065] 300g of 55% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co₂B / Co₃B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 70℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 52.6%, the conversion rate was 100%, and the selectivity was 95.6%. Vacuum distillation yielded 167.7g of crude cashmereone, and vacuum fractionation yielded 164.9g of the final product with a cashmereone content of 99.0%, with a yield of 93.3%.

[0066] Example 6

[0067] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0068] 300g of 65% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co2B / Co3B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 85℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 63.1%, the conversion rate was 100%, and the selectivity was 97.0%. 202.0g of crude cashmereone was obtained by vacuum distillation, and 200.1g of a product with a cashmereone content of 99.0% was obtained by vacuum fractionation, with a yield of 94.8%.

[0069] Example 7

[0070] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0071] 300g of 55% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co₂B / Co₃B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 100℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 52.8%, the conversion rate was 100%, and the selectivity was 96.0%. Vacuum distillation yielded 168.1g of crude cashmereone, and vacuum fractionation yielded 166.0g of the final product with a cashmereone content of 98.9%, with a yield of 92.9%.

[0072] Example 8

[0073] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0074] 300g of 55% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co2B / Co3B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 120℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 51.2%, the conversion rate was 100%, and the selectivity was 93.0%. Vacuum distillation yielded 161.0g of crude cashmereone, and vacuum fractionation yielded 161.3g of the final product with a cashmereone content of 98.8%, with a yield of 90.1%.

[0075] Example 9

[0076] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0077] 300g of 55% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co2B / Co3B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 50℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was ≥53.9%, the conversion rate was 100%, and the selectivity was 98.0%. 171.0g of crude cashmereone was obtained by vacuum distillation, and 169.2g of a finished product with a cashmereone content of 99.1% was obtained by vacuum fractionation, with a yield of 94.9%.

[0078] Example 10

[0079] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0080] 300g of 55% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. A mixture of 2g of cobalt diboride and cobalt triboride (Co₂B / Co₃B = 1:1) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 150℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 48.6%, the conversion rate was 100%, and the selectivity was 88.4%. Vacuum distillation yielded 152.0g of crude cashmereone, and vacuum fractionation yielded 148.1g of the final product with a cashmereone content of 98.0%, with a yield of 82.1%.

[0081] Example 11

[0082] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0083] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 2g of cobalt boride (CoB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 1.0MPa for 7 hours. Gas chromatography analysis showed that the cashmereone content was 72.9%, the conversion rate was 100%, and the selectivity was 97.2%. Vacuum distillation yielded 232.0g of crude cashmereone, and vacuum fractionation yielded 229.8g of a finished product with a cashmereone content of 99.0%, a yield of 94.4%.

[0084] Example 12

[0085] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0086] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 4g of cobalt boride (CoB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 1.0MPa for 7 hours. Gas chromatography analysis showed that the cashmereone content was 73.9%, the conversion rate was 100%, and the selectivity was 98.5%. Vacuum distillation yielded 235.1g of crude cashmereone, and vacuum fractionation yielded 232.6g of a finished product with a cashmereone content of 98.0%, with a yield of 94.6%.

[0087] The mass spectra of the product prepared in this embodiment are as follows: Figure 2 As shown, the upper figure is the mass spectrum of the cashmereone standard, and the lower figure is the mass spectrum of the product prepared in this embodiment. The two are consistent, indicating that the product obtained by the method of the present invention is the target product.

[0088] Example 13

[0089] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0090] 300g of 60% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 2g of nickel boride (NiB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 80℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was ≥54.1%, the conversion rate was 100%, and the selectivity was 90.2%. Vacuum distillation yielded 171.8g of crude cashmereone, and vacuum fractionation yielded 168.9g of a finished product with a cashmereone content of 98.0%, with a yield of 85.8%.

[0091] Example 14

[0092] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0093] 300g of 70% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 4g of nickel boride (NiB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 1.0MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 63.7%, with a conversion rate of 100% and a selectivity of 91.0%. Vacuum distillation yielded 202.5g of crude cashmereone, and vacuum fractionation yielded 199.2g of the final product with a cashmereone content of 98.1%, a yield of 86.9%.

[0094] Example 15

[0095] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0096] 300g of 60% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 4g of nickel boride (NiB) was added as a catalyst, and air was introduced as the oxygen source. The mixture was heated to 80℃ and reacted at 0.9MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 54.0%, the conversion rate was 100%, and the selectivity was 90.0%. Vacuum distillation yielded 170.8g of crude cashmereone, and vacuum fractionation yielded 168.5g of the final product with a cashmereone content of 98.0%, a yield of 85.7%.

[0097] Example 16

[0098] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0099] 300g of 70% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 3g of nickel boride (NiB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 95℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the cashmereone content was 64.2%, the conversion rate was 100%, and the selectivity was 91.8%. Vacuum distillation yielded 202.9g of crude cashmereone, and vacuum fractionation yielded 196.9g of the final product with a cashmereone content of 98.2%, a yield of 86.0%.

[0100] Example 17

[0101] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0102] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 5g of chromium boride (CrB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 80℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 68.0%, with a conversion rate of 100% and a selectivity of 90.6%. Vacuum distillation yielded 213.4g of crude cashmereone, and vacuum fractionation yielded 199.9g of the final product with a cashmereone content of 98.0%, a yield of 81.3%.

[0103] Example 18

[0104] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0105] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 5g of manganese boride (MnB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 0.9MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 69.0%, the conversion rate was 100%, and the selectivity was 92.1%. Vacuum distillation yielded 223.8g of crude cashmereone, and vacuum fractionation yielded 218.0g of the final product with a cashmereone content of 98.0%, a yield of 88.7%.

[0106] Example 19

[0107] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0108] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 3g of ferric boride (FeB) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 1.0MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 69.9%, the conversion rate was 100%, and the selectivity was 93.2%. Vacuum distillation yielded 223.9g of crude cashmereone, and vacuum fractionation yielded 221.6g of the final product with a cashmereone content of 98.1%, a yield of 90.2%.

[0109] Example 20

[0110] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0111] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 3g of vanadium boride (VB2) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 0.9MPa for 7 hours. Gas chromatography analysis showed that the cashmereone content was 67.1%, the conversion rate was 100%, and the selectivity was 89.5%. Vacuum distillation yielded 216.7g of crude cashmereone, and vacuum fractionation yielded 213.5g of the final product with a cashmereone content of 98.6%, a yield of 87.4%.

[0112] Example 21

[0113] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0114] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 4g of titanium boride (TiB2) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 80℃ and reacted at 0.8MPa for 7 hours. Gas chromatography analysis showed that the main peak content of cashmereone was 65.1%, with a conversion rate of 100% and a selectivity of 86.9%. Vacuum distillation yielded 207.9g of crude cashmereone, and vacuum fractionation yielded 205.9g of the final product with a cashmereone content of 98.5%, a yield of 84.2%.

[0115] Example 22

[0116] In this embodiment, a method for preparing cashmereone is provided, comprising the following steps:

[0117] 300g of 75% pure 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene was added to a 500mL dry high-pressure reactor. 4g of copper boride (Cu3B2) was added as a catalyst, and oxygen was introduced as the oxygen source. The mixture was heated to 90℃ and reacted at 0.9MPa for 7 hours. Gas chromatography analysis showed that the cashmereone main peak content was 68.7%, with a conversion rate of 100% and a selectivity of 91.6%. Vacuum distillation yielded 221.8g of crude cashmereone, and vacuum fractionation yielded 218.8g of the final product with a cashmereone content of 98.3%, a yield of 89.3%.

[0118] Comparative Example 1

[0119] In the 2013 supplement to the journal *Fragrance, Flavor and Cosmetics*, authors Gu Yuncui, Li Buxiang, and Huan Yueqin published a synthetic method for preparing indane (cashmereone) using sodium dichromate to oxidize pentamethyltetrahydroindane. Using this method as a control, 100g of raw material (containing 55% pentamethyltetrahydroindane alcohol) was added to a 1000mL glass bottle equipped with a stirrer, thermometer, reflux condenser, and feeding funnel. The mixture was heated and stirred until the internal temperature reached 50°C. Then, 150g of a solution of sodium dichromate containing two molecules of water of crystallization dissolved in 600g of glacial acetic acid was slowly added dropwise through the feeding funnel. The reaction was slightly exothermic, and the temperature was maintained between 50-100°C. The addition was completed over 2 hours, and the reaction was continued at 100°C for another 4 hours. Analysis of the reaction solution showed a 30.9% pentamethylindane content, a conversion rate of approximately 40%, no indane alcohol, an indaneone content of 9.7%, and a yield of 17.6%.

[0120] As can be seen from the above, this invention, verified through multiple experiments, can complete the synthesis of cashmereone from tetrahydropentamethylindene using a single oxidation method. Using a mixture of cobalt diboride and cobalt triboride (Co2B / Co3B = 1:1) as a catalyst, at a high-pressure reactor temperature of 5–70°C, the conversion rate of cashmereone at the end of the reaction is 45–100%, the selectivity is 95–99%, and the yield of the cashmereone product is 82–97%; at a temperature of 70–120°C, the conversion rate of cashmereone at the end of the reaction is 100%, the selectivity is 93–98%, and the yield of the cashmereone product is 90–95%; at a temperature of 120–250°C, the conversion rate of cashmereone at the end of the reaction is 100%, the selectivity is 88–98%, and the yield of the cashmereone product is 82–95%. Cobalt boride (CoB) as a catalyst exhibits performance consistent with the above-mentioned catalysts. Nickel boride (NiB), chromium boride (CrB), manganese boride (MnB), iron boride (FeB), vanadium boride (VB2), titanium boride (TiB2), and copper boride (Cu3B2) exhibit weaker catalytic performance than mixtures of cobalt diboride (Co2B) and cobalt triboride (Co3B) and cobalt boride (CoB). Their low-temperature reactions are poor or even non-existent. The above experiments confirm that substances combining cobalt and boron are the best catalysts for this type of reaction.

[0121] The applicant declares that the present invention illustrates the preparation method of cashmereone through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing cashmereone, characterized in that, The preparation method includes the following steps: In the presence of an oxygen source, 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane undergoes an oxidation reaction catalyzed by a boride catalyst to yield cashmereone; The borides are selected from one or a combination of at least two of the following: manganese boride, nickel boride, nickel boride, iron boride, ferrous boride, chromium boride, chromium diboride, cobalt boride, cobalt diboride, tricobalt boride, cobalt diboride, vanadium boride, titanium boride, or copper boride.

2. The preparation method according to claim 1, characterized in that, The boride is selected from a mixture of at least two of cobalt boride, cobalt diboride, or cobalt triboride.

3. The preparation method according to claim 1, characterized in that, The purity of the 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is 10%-100%.

4. The preparation method according to claim 3, characterized in that, The purity of the 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is 45.0%-80.0%.

5. The preparation method according to claim 1, characterized in that, The catalyst is used in an amount of 0.1%-20% of the full mass of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene.

6. The preparation method according to claim 5, characterized in that, The catalyst is used in an amount of 3.0%-5.0% of the full mass of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindene.

7. The preparation method according to claim 1, characterized in that, The oxygen source is pure oxygen or air.

8. The preparation method according to claim 1, characterized in that, The oxidation reaction is carried out at a temperature of 5-250℃.

9. The preparation method according to claim 8, characterized in that, The oxidation reaction is carried out at a temperature of 70-100℃.

10. The preparation method according to claim 1, characterized in that, The oxidation reaction was carried out at a pressure of 0.8 MPa-10.0 MPa.

11. The preparation method according to claim 10, characterized in that, The oxidation reaction is carried out at a pressure of 0.8-1.2 MPa.

12. The preparation method according to claim 1, characterized in that, The oxidation reaction takes 6-9 hours.

13. The preparation method according to claim 1, characterized in that, After the oxidation reaction is completed, the reaction solution is subjected to vacuum distillation and vacuum rectification to obtain cashmereone.

14. A method for preparing cashmereone, characterized in that, The preparation method includes the following steps: In the presence of an oxygen source, 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is oxidized for 6-9 h at 5-250 °C and 0.8 MPa-10.0 MPa under the catalysis of a boride catalyst to obtain cashmereone. The oxygen source is pure oxygen or air; the boride is selected from one or a combination of at least two of manganese boride, nickel boride, nickel boride, iron boride, ferric boride, chromium boride, chromium diboride, cobalt boride, cobalt diboride, cobalt triboride, cobalt diboride, vanadium boride, titanium boride, or copper boride; the purity of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane is 10%-100%; and the amount of catalyst used is 0.1%-20% of the mass of 1,1,2,3,3-pentamethyl-4,5,6,7-tetrahydroindane.

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