CN112250556B - Preparation method of menthone - Google Patents
Preparation method of menthone Download PDFInfo
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- CN112250556B CN112250556B CN202011142390.8A CN202011142390A CN112250556B CN 112250556 B CN112250556 B CN 112250556B CN 202011142390 A CN202011142390 A CN 202011142390A CN 112250556 B CN112250556 B CN 112250556B
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- isopulegol
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C49/00—Ketones; Ketenes; Dimeric ketenes; Ketonic chelates
- C07C49/385—Saturated compounds containing a keto group being part of a ring
- C07C49/403—Saturated compounds containing a keto group being part of a ring of a six-membered ring
- C07C49/407—Menthones
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
- C07C45/511—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups
- C07C45/512—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups the singly bound functional group being a free hydroxyl group
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
- C07B2200/00—Indexing scheme relating to specific properties of organic compounds
- C07B2200/07—Optical isomers
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2601/00—Systems containing only non-condensed rings
- C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
- C07C2601/14—The ring being saturated
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a preparation method of menthone. The method can efficiently transfer intramolecular hydrogen of isopulegol through photocatalytic reaction to obtain menthone. The method solves the problem of easy production of isomenthone in the preparation process of menthone, and has the advantages of easily available raw materials, simple operation, high product yield and low separation difficulty.
Description
Technical Field
The invention belongs to the field of spice synthesis, and particularly relates to a preparation method of menthone.
Background
Menthone, also known as menthone, has the cooling characteristic aroma of natural mint. The menthone compound is mainly used for preparing mint type essence, and besides, the menthone has the effects of cooling, easing pain and relieving itching, and experiments also prove that the menthone compound possibly has the effect of resisting depression, so that the synthesis of the menthone is always concerned by people.
Current menthone products include both natural menthone and synthetic menthone. The natural menthone is mainly obtained by rectifying and extracting natural raw materials such as natural mint, geranium and the like, and the price and supply of the natural menthone are obviously influenced by the raw materials. The method for synthesizing menthone is numerous, mainly takes the oxidation of menthol as a main part, adopts a stoichiometric oxidation system such as chromate, permanganate, hypochlorite and the like, and although the process of the route is mature, the oxidant involved in the process is toxic or dangerous, and a large amount of volatile organic solvent is needed when the process is used, so a large amount of waste liquid and byproduct salt are generated in the production process.
Patent US3124614 reports that menthone can be obtained by hydrogenating thymol under the action of Pd catalyst, but thymol as a raw material is not easily obtained, reaction conditions are severe, requirements for equipment materials are high, and equipment cost is high.
Patent CN106061933 reports a process for the preparation of menthone by contacting isopulegol in the gas phase with an activated oxidizing copper catalyst.
Patent CN106068160 describes a ruthenium-phenol catalyst for transfer hydrogenation and uses this catalyst for the preparation of menthone from isopulegol.
The menthone products obtained in the above reports are all mixtures of menthone of formula (II) and isomenthone of formula (III), and the selectivity is poor. Menthone and isomenthone are stereoisomers, close in nature, and difficult to separate.
Therefore, a method which is simple in process, mild in reaction conditions, economical, efficient, environment-friendly and easy to realize industrialization is urgently needed to realize the preparation of the high-selectivity menthone.
Disclosure of Invention
In order to solve the problems, the invention provides a preparation method of menthone in a formula (II), which can be used for preparing menthone by starting from isopulegol in a formula (I) and selectively catalyzing isopulegol to perform hydrogen transfer through photochemical reaction, and the isomulegone is not easy to generate. The method has the advantages of simple operation, low catalyst cost, high product yield, less three wastes and the like, does not need hydrogen through the hydrogenation transfer process, has better process safety, and is suitable for industrial production and application.
In order to achieve the above purpose, the invention adopts the following technical scheme:
in the presence of silver catalyst, isopulegol produces selective intramolecular hydrogen transfer reaction through photochemical reaction to obtain menthone.
In the invention, the preparation method comprises the following steps: adding isopulegol, a solvent and a silver catalyst into a reaction kettle, stirring, introducing inert gas, controlling the reaction temperature, and turning on a light source to perform a hydrogen transfer reaction.
In the present invention, the isopulegol is L-isopulegol in the form of formula (I) and/or its enantiomer D-menthol, and the menthone is L-menthone in the form of formula (II) and/or its enantiomer D-menthone.
In the invention, the L-isopulegol and the D-isopulegol in the isopulegol can be in any proportion.
In the present invention, the silver-based catalyst is one or more selected from the group consisting of silver sulfate, silver chloride, silver phosphate, silver acetate and silver triflate, and preferably silver triflate.
In the present invention, the molar amount of the silver catalyst is 0.001mol% to 1mol%, preferably 0.001mo1% to 0.5mo1%, and more preferably 0.002mo1% to 0.1mo1% in terms of silver atoms, based on the molar amount of isopulegol.
In the present invention, the optical purity of L-isopulegol in the starting material isopulegol is not particularly limited, and may be any optical purity, for example, the enantiomeric excess of L-isopulegol in the isopulegol with respect to D-isopulegol is any value of 0% to 98% ee, for example, 0% ee, 30% ee, 50% ee, 70% ee, 85% ee, 98% ee.
In the invention, the mass concentration of the isopulegol in the solvent is 5-50%, preferably 10-30%;
in the invention, the solvent is one or more of alkane, aromatic hydrocarbon, ether and alcohol, preferably one or more of n-hexane, xylene, tetrahydrofuran and cyclohexanol.
In the present invention, the inert gas is a high purity nitrogen gas and/or a high purity argon gas having an oxygen content of less than 20ppm (v/v).
In the invention, the photocatalytic hydrogen transfer reaction needs to occur under specific illumination conditions, and the light source is one or more of a mercury lamp, a xenon lamp and a metal halide lamp; preferably, the wavelength of the light source is 300-800 nm, preferably 500-600 nm.
In the invention, the temperature of the hydrogen transfer reaction is-10-30 ℃, preferably-10 ℃; the reaction time is 6-24 h, preferably 8-12 h.
In the invention, the conversion rate of the reaction is 90-99.9%, and the chemical selectivity is 91-99%.
It is another object of the present invention to provide a menthone product.
Menthone is prepared by adopting the method for preparing menthone.
The technical scheme provided by the invention has the following beneficial effects:
(1) under the condition of room temperature, isopulegol can generate intramolecular hydrogen transfer, the product menthone can be obtained with high selectivity, and the selectivity reaches more than 91 percent, thereby solving the problem that the preparation process of the menthone is easy to generate the isopulegone.
(2) The method has the advantages of simple operation, low catalyst cost, high product yield and less three wastes.
Detailed description of the invention
The following examples are intended to illustrate the invention without limiting it in any way.
The analysis method comprises the following steps:
gas chromatograph: agilent7890, chromatographic column DB-5, injection port temperature: 300 ℃; the split ratio is 50: 1; carrier gas flow: 52.8 ml/min; temperature rising procedure: holding at 120 ℃ for 15min, increasing to 250 ℃ at a rate of 10 ℃/min, holding for 10min, detector temperature: 280 ℃.
The use of the medicine:
l-isopulegol, not less than 95 wt%, pharmaceutical chemical Limited of Hubei Julongtang;
silver sulfate, silver chloride, silver phosphate, silver acetate, silver triflate, not less than 99.5 wt%, Aladdin reagent Co., Ltd;
copper oxide, aluminum oxide, magnesium oxide, aluminum copper oxide, not less than 99.5 wt%, Nanjing chemical reagents GmbH;
high purity nitrogen (99.999%), shanghai garget gas ltd;
high purity argon (99.999%), shanghai garget gas limited,
hydrogen (99.999%), shanghai garget gas limited.
Light source: 300W mercury lamp light source CME-M300, Zhongke micro energy (Beijing) science and technology Limited; xenon lamp light source MAX-303, Knoop, Beijing technologies, Inc.
A reactor: photochemical temperature-controlled integrated reactor GUIGO-RDPR10S, Shanghai Guige industries, Inc.
Example 1
463g of n-hexane, 154.3g (1.0mol) of isopulegol (25 mass percent) and 15.59mg (0.05mmol) of silver sulfate (0.01 mol percent relative to isopulegol) are added into a photochemical reactor in an oxygen-free and water-free atmosphere, the mixture is stirred for 30min until the mixture is clear and transparent, high-purity nitrogen gas is introduced into the reactor, then the temperature is kept at 0 ℃, a mercury lamp in the reactor is opened, the wavelength is controlled to be 550nm, and the mixture is irradiated for 10h at the power of 300W until the reaction is finished. Conversion was then determined by calibration GC analysis to be 95.5% with a menthone yield of 96.7%.
Example 2
Under an oxygen-free and water-free atmosphere, 154.3g of n-hexane, 154.3g (1.0mol) of isopulegol (the mass fraction is 50%) and 143.3mg (1mmol) of silver chloride (0.1 mol% relative to isopulegol) are added into a photochemical reactor, stirred for 30min until the mixture is clear and transparent, high-purity nitrogen gas is introduced into the reactor, then the temperature is kept at-10 ℃, a xenon lamp in the reactor is turned on, the wavelength is controlled to be 300nm, and the irradiation is carried out for 8h at the power of 300W until the reaction is finished. Conversion was then determined by calibration GC analysis to be 99.9% and menthone yield 97.5%.
Example 3
5863.4g of xylene, 308.6g (2.0mol) of isopulegol (5 mass percent) and 6.279mg (0.015mmol) of silver phosphate (0.002 mol percent relative to isopulegol) are added into a photochemical reactor under an oxygen-free and water-free atmosphere, the mixture is stirred for 30min until the mixture is clear and transparent, high-purity nitrogen gas is introduced into the reactor, then the temperature is kept at 5 ℃, a mercury lamp in the reactor is opened, the wavelength is controlled to be 600nm, and the mixture is irradiated for 12h at the power of 300W until the reaction is finished. Conversion was then determined by calibration GC analysis to be 90.0% and menthone yield 91.0%.
Example 4
874.4g of xylene, 154.3g (1.0mol) of isopulegol (15 mass percent) and 83.45mg (0.5mmol) of silver acetate (0.05 mol percent relative to isopulegol) are added into a photochemical reactor in an oxygen-free and anhydrous atmosphere, the mixture is stirred for 30min until the mixture is clear and transparent, high-purity argon gas is introduced into the reactor, then the temperature is kept at 10 ℃, a xenon lamp in the reactor is turned on, the wavelength is controlled to be 500nm, and the mixture is irradiated for 6h at the power of 300W until the reaction is finished. Conversion was then determined by calibration GC analysis to be 94.5% with a menthone yield of 97.8%.
Example 5
720.1g of cyclohexanol, 308.6g (2.0 mol%) of isopulegol (30% by mass) and 5.642mg (0.02mmol) of silver trifluoromethanesulfonate (0.001 mol% relative to isopulegol) were charged into a photochemical reactor under an oxygen-free and water-free atmosphere, stirred for 30min until mixed, clear and transparent, and high-purity nitrogen gas was introduced into the reactor, followed by maintaining the temperature at 20 ℃ and opening the mercury lamp in the reactor, controlling the wavelength at 800nm, irradiating at a power of 300W for 24h until the reaction was followed by measuring the conversion of 98.7% and the yield of menthone by a calibration GC analysis to 99.0%.
Example 6
462.9g of cyclohexanol, 154.3g (1.0mol) of isopulegol (25 mass percent) and 1.433g (10mmol) of silver chloride (1 mol percent relative to isopulegol) are added into a photochemical reactor in an oxygen-free and anhydrous atmosphere, the mixture is stirred for 30min until the mixture is clear and transparent, high-purity argon gas is introduced into the reactor, then the temperature is kept at 30 ℃, a xenon lamp in the reactor is turned on, the wavelength is controlled to be 400nm, and the mixture is irradiated for 15h at the power of 300W until the reaction is finished. Conversion was then determined by calibration GC analysis to be 96.8% with a menthone yield of 96.6%.
Comparative example 1
The scheme of the prior art CN106061933 is adopted, isopulegol is also used as a raw material to isomerize and generate the menthone, and the difference is that a conventional catalyst and a gas-phase catalytic reaction are used, and the scheme generates a large amount of isomenthone.
Mixing X540T 1/8(150g, 30-40% copper oxide, 10-25% aluminum oxide, 10-25% magnesium oxide and 30-40% aluminum copper (Al)2CuO4) Charging into a gas phase reactor and reacting the catalyst in the presence of H2Activation at a temperature of 170-180 ℃ under a gas stream (20-40 NL/h).The evaporator and reactor were subsequently operated at a temperature of 170 ℃ and at atmospheric pressure with a nitrogen stream (20 NL/h). Isopulegol (15g/h, 97.2mmol/h) is introduced continuously into the evaporator. The product mixture was condensed at the reactor outlet and the conversion was determined by calibration GC analysis to be 100%, the menthone selectivity 59.2% and the isomenthone selectivity 29.3%.
From the results of the above examples and comparative examples, it was found that isopulegol can efficiently and selectively produce menthone without producing isomenthone by a photocatalytic reaction in the presence of a silver-based catalyst, and the method solves the problem that isomenthone is easily produced in the process of preparing menthone.
It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.
Claims (13)
1. A method for preparing menthone is characterized in that isopulegol generates selective intramolecular hydrogen transfer reaction under the existence of a silver catalyst and under the condition of a light source with the wavelength of 300-800 nm through photochemical action to obtain the menthone;
the isopulegol is L-isopulegol in a form of a formula (I) and/or D-menthol enantiomer thereof, the menthone is L-menthone in a form of a formula (II) and/or D-menthone enantiomer thereof,
the L-isopulegol and the D-isopulegol in the isopulegol are in any proportion.
2. The method according to claim 1, wherein the steps of the preparation method are: adding isopulegol, a solvent and a silver catalyst into a reaction kettle, stirring, introducing inert gas, controlling the reaction temperature, and turning on a light source to perform a hydrogen transfer reaction.
3. The method according to claim 1 or 2, wherein the silver-based catalyst is selected from one or more of silver sulfate, silver chloride, silver phosphate, silver acetate, and silver triflate;
and/or, the molar amount of the silver-based catalyst is 0.001mol% to 1mol% in terms of silver atoms, based on the molar amount of isopulegol.
4. The method according to claim 3, wherein the silver-based catalyst is silver triflate;
and/or, the molar amount of the silver-based catalyst is 0.001mo1% to 0.5mo1% in terms of silver atoms, based on the molar amount of isopulegol.
5. The method of claim 4, wherein the molar amount of the silver-based catalyst is 0.002mo1% -0.1mo1% in terms of silver atoms, based on the molar amount of isopulegol.
6. The method according to claim 2, wherein the mass concentration of isopulegol in the solvent is 5% to 50%;
and/or the solvent is one or more of alkane, aromatic hydrocarbon, ether and alcohol.
7. The method according to claim 6, wherein the mass concentration of isopulegol in the solvent is 10% to 30%;
and/or the solvent is one or more of n-hexane, xylene, tetrahydrofuran and cyclohexanol.
8. The method of claim 2, wherein the inert gas is high purity nitrogen and/or high purity argon having an oxygen volume ratio of less than 20 ppm.
9. The method of claim 1 or 2, wherein the light source is one or more of a mercury lamp, a xenon lamp, and a metal halide lamp.
10. The method according to claim 1 or 2, wherein the light source wavelength is 500 to 600 nm.
11. The method according to claim 1 or 2, wherein the temperature of the hydrogen transfer reaction is-10 to 30 ℃ and the reaction time is 6 to 24 hours.
12. The method according to claim 11, wherein the temperature of the hydrogen transfer reaction is-10 to 10 ℃ and the reaction time is 8 to 12 hours.
13. The process according to claim 1 or 2, characterized in that the reaction has a conversion of 90% to 99.9% and a chemoselectivity of 91% to 99%.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106061933A (en) * | 2014-03-07 | 2016-10-26 | 巴斯夫欧洲公司 | Method for producing menthones from isopulegol in the gas phase |
| CN107602357A (en) * | 2017-09-28 | 2018-01-19 | 万华化学集团股份有限公司 | A kind of method for preparing menthones |
| CN109651115A (en) * | 2018-12-25 | 2019-04-19 | 万华化学集团股份有限公司 | A method of preparing L- menthones |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9029605B2 (en) * | 2012-09-10 | 2015-05-12 | Basf Se | Method for preparing menthone from isopulegol |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106061933A (en) * | 2014-03-07 | 2016-10-26 | 巴斯夫欧洲公司 | Method for producing menthones from isopulegol in the gas phase |
| CN107602357A (en) * | 2017-09-28 | 2018-01-19 | 万华化学集团股份有限公司 | A kind of method for preparing menthones |
| CN109651115A (en) * | 2018-12-25 | 2019-04-19 | 万华化学集团股份有限公司 | A method of preparing L- menthones |
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