Alpha ionone composition and preparation method thereof

Abstract

The invention provides an alpha ionone composition and a preparation method thereof. The alpha ionone composition comprises ionone, an isomer and 0.0001-0.01 wt% of an impurity A, wherein the structure of the impurity A is as shown in a formula 1: # imgabs0 #. The generation of the key impurity A is controlled by limiting the content of the preisomer impurity of the pseudoionone in the reaction raw materials, the method is simple to operate, a typical violet fragrance product can be obtained, the fragrance quality of the product is superior to that of a competitive product in the market, and the product is applied to high-end cosmetics and daily cosmetics.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to an alpha ionone composition and a preparation method thereof. Background Art

[0002] α-ionone is a traditional synthetic fragrance that plays an irreplaceable role in flavor blending. Because it can be well blended with many floral and woody fragrances, it can be used as a blending agent, modifier and base fragrance raw material. The existing synthesis method mainly uses pseudoionone as a raw material and undergoes an acid-catalyzed cyclization reaction to obtain α-ionone products.

[0003] At present, the synthesis methods of α-ionone that have been industrialized all use acid as a catalyst. There have been many studies on the cyclization reaction itself, such as Chinese patent CN1508113, US patent US4565894 and Chinese patent CN106278853A. Although the α-ionone prepared by the existing technology can reach a certain purity, the aroma of α-ionone produced by various manufacturers is uneven. The top note of the violet flower fragrance has the smell of ripe fruit, which affects the aroma of the product and leads to the failure of the fragrance α-ionone product.

[0004] In view of this problem, providing an α-ionone that can obtain a stable aroma and a preparation method thereof is of great significance. Summary of the invention

[0005] In view of the above problems existing in the prior art, the object of the present invention is to provide an α-ionone composition and a preparation method thereof.

[0006] The inventors of this application have discovered through experimental research that the key impurity A that affects the floral aroma of α-ionone is a ripe fruit aroma that masks the top notes of the violet floral aroma and reduces the product quality. If the impurity is reduced to a certain concentration, the impact of the odor can be eliminated. Unfortunately, the impurity has a boiling point close to that of the product. Conventional distillation separation requires a negative pressure of <10pa and greater than 75 plates to separate it. The conditions are too harsh, the energy consumption is high, and the yield is low. At present, the content of the impurity A in α-ionone is usually 0.1-3wt%.

[0007] The inventors found through further research that the impurity A is obtained by the cyclization reaction of the pro-isomer impurity of the pseudo-ionone raw material. Therefore, the present invention is an ideal measure to pre-treat the raw material pseudo-ionone before the reaction to reduce the pro-isomer impurity to the target content before the cyclization reaction.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides an α-ionone composition, comprising ionone and isomers, and an impurity A in an amount of 0.0001-0.01 wt%, for example, 0.0001 wt%, 0.0005 wt%, 0.001 wt%, 0.002 wt%, 0.003 wt%, 0.004 wt%, 0.005 wt%, 0.006 wt%, 0.007 wt%, 0.008 wt%, 0.009 wt%, 0.01 wt%, etc.; wherein the structure of impurity A is shown in Formula 1:

[0010]

[0011] Structural characterization, NMR data: H1NMR (400HZ CDCl3)δ1.25(6H,s),1.29(2H,t),1.96(2H,m),2.21(3H,s),2.24(3H,s),5.43(1H,t),6.22(1H,d),6.33(1H,d),16.77(1H,s).

[0012] In the α-ionone composition of the present invention, ionone and isomers include α-ionone, and isomers such as β-ionone and γ-ionone, wherein the proportion of α-ionone is maintained at 70-90wt%.

[0013] In a second aspect, the present invention provides a method for preparing the α-ionone composition, which can be prepared from crude α-ionone by any conventional separation method disclosed in the art, or prepared using pseudo-ionone as a raw material by the following cyclization method, and the present invention has no special requirements.

[0014] In a specific example, the present invention provides a method for preparing the α-ionone composition, which comprises mixing pseudo-ionone with a solvent, and obtaining the α-ionone composition by a cyclization reaction under the action of an acid catalyst; wherein the content of pseudo-ionone pro-isomer impurities in the pseudo-ionone is controlled to be ≤0.01wt%, for example, 0.01wt%, 0.009wt%, 0.008wt%, 0.007wt%, 0.005wt%, 0.003wt%, 0.001wt%, 0.0005wt%, 0.0001wt%, etc.

[0015] The purity of pseudoionone raw materials currently on the market is generally greater than 90%, and the content of the pro-isomer impurity is less than 10wt%. The structures of pseudoionone and its pro-isomer are as follows:

[0016]

[0017] Pseudo-ionone pre-isomer impurities can also participate in the acid-catalyzed cyclization reaction to generate impurity A with a fruity aroma, which has a boiling point close to that of the main product ionone and isomers and is difficult to separate by conventional distillation; Patent CN113548952 proposes to reduce the content of pseudo-ionone pre-isomer impurities by controlling the reaction, but it still does not reach the control range required by the present invention. To this end, the present invention provides a method for pretreatment based on the pseudo-ionone principle.

[0018] In the present invention, if the content of pseudoionone pro-isomer impurities in the pseudoionone raw material is greater than 0.01wt%, the pseudoionone pro-isomer can be converted into pseudoionone by a metal-catalyzed isomerization reaction; this method can make the content of pro-isomer impurities ≤ 0.01wt%.

[0019] Specifically, the pseudoionone raw material that can be used for isomerization reaction conversion has a pre-isomer impurity mass content >0.01%, which can be 0.1%, 0.5%, 0.6%, 0.8%, 1.1%, 1.5%, 1.8%, 2.0%, 2.5%, 3.0%, 3.5%, 4.5%, 5.5%, 6.5%, 7.0%, 9.5%, etc. The impurity content of commercially available pseudoionone is generally <10%.

[0020] An isomerization reaction mode proposed in the present invention is a metal-catalyzed isomerization reaction transposition, which can adopt a fixed bed reactor, and the metal catalyst adopted is one or more of Pt-Rh / Al2O3, Pt-Ru / Al2O3, Pt-Ir / Al2O3, Pt-Pd / Al2O3, Pt-Ni / Al2O3, and Pt-Co / Al2O3;

[0021] The isomerization reaction has a reaction temperature of 30-60°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, etc., preferably 50-60°C; the residence time is 10-300min, for example, 10min, 20min, 30min, 50min, 60min, 90min, 100min, 150min, 210min, 220min, 250min, 300min, etc., preferably 60-150min.

[0022] Preferably, the isomerization reaction is carried out in an inert atmosphere, and the inert atmosphere is selected from one of nitrogen, argon and helium.

[0023] This isomerization method is simple to operate, can be carried out continuously, and the material system does not contain impurities that are toxic to the activity of metals. The operation cycle is >1 year, which is suitable for industrialization.

[0024] It should be noted that the above method disclosed in the present invention is only used to illustrate one of the catalytic conversion methods used to achieve the pseudoionone with low pro-isomer impurity content (≤0.01wt%) described in the present invention. The source of the pseudoionone raw material described in the present invention should not be limited by the steps and parameters in the above method.

[0025] The α-ionone composition described above is prepared by mixing pseudo-ionone with the same solvent and then reacting with an acid as a catalyst for cyclization, which is a known process in the art. The relevant operations and process conditions in the preparation method of the present invention, and the devices used therein, can all be carried out by using the corresponding conventional selections in the art, and there is no particular limitation thereto. The technician can optimize the process based on the known processes in the prior art according to actual needs, and specifically, for example, the conditions listed in the following embodiments of the present invention can be used:

[0026] In the present invention, the solvent is one or a combination of benzene, toluene, xylene, cumene, tetrahydrofuran, chloroform, ether, anisole, n-hexane and the like.

[0027] Preferably, the mass ratio of the pseudoionone to the solvent is 1:0.1-5, for example, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, etc., more preferably 1:0.5-2.

[0028] In the present invention, the acid catalyst includes one or more of phosphoric acid, sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid;

[0029] Preferably, the amount of the acid catalyst is 0.1-1 times the mass of pseudoionone, such as 0.1 times, 0.2 times, 0.3 times, 0.5 times, 0.8 times, 1 times, etc.; specifically, the acid catalyst can be configured into a 20-99wt% aqueous solution for use.

[0030] In the present invention, the cyclization reaction, the reaction temperature is 40-90°C, for example, 50°C, 55°C, 60°C, 75°C, 80°C, 90°C, etc., preferably 50-80°C; the reaction time is 1-12h, for example, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 11h, 12h, etc., preferably 4-8h;

[0031] Preferably, at the beginning of the reaction, pseudoionone and solvent can be first laid down in a certain ratio, and after reaching the reaction temperature, the acid catalyst can be added in the form of drops for 1-2 hours, and the drop addition time is not included in the total reaction time; of course, all raw materials can also be added in a conventional one-pot method.

[0032] In the present invention, after the cyclization reaction is completed, post-treatment processes such as washing and distillation are also included, which are conventional operations in the field and have no special requirements. For example, the post-treatment method used in some specific examples is: the cyclization reaction liquid is washed with water, desolventized, and distilled to obtain α-ionone.

[0033] The α-ionone composition prepared by the method of the present invention has an α-ionone ratio of 70-90wt%, such as 70%, 75%, 80%, 85%, 90%, etc.; the impurity A content is 0.0001-0.01wt%, and the rest is isomers such as β-ionone and γ-ionone.

[0034] Compared with the prior art, the positive effects of the technical solution of the present invention are:

[0035] The present invention first identifies the key impurity A that affects the floral aroma of alpha-ionone, and controls the generation of impurity A by limiting the content of the pro-isomer impurity of pseudo-ionone in the reaction raw materials. The method is simple to operate and can obtain a product with a typical violet floral aroma. The aroma quality of the product is better than that of competing products on the market, and the product is used in high-end cosmetics and daily cosmetics. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific examples. These examples are only for illustrating the present invention and are not to be construed as limiting the scope of the present invention or the method for implementing the present invention.

[0037] The sources of the main raw materials in the examples and comparative examples of the present invention are as follows. Other sources are obtained from common commercial channels unless otherwise specified:

[0038] Metal supported catalyst: Aladdin Reagents;

[0039] Phosphoric acid: Aladdin Reagents;

[0040] Pseudoionone: MacLean Reagent Company (purity>90%, pro-isomer content<10%).

[0041] The performance test parameters and corresponding test methods used in various embodiments of the present invention are as follows:

[0042] Aroma evaluation: scored by three experienced perfumers according to GB / T 14454.2-2008;

[0043] The purity of the product was detected by gas chromatography, and the specific analysis conditions were as follows: instrument: Agilent gas chromatograph 8890, chromatographic column: Agilent DB-5, column box temperature: 80°C; inlet temperature: 300°C; detector temperature: 310°C; split ratio 10:1; carrier gas flow rate: 1mL / min; heating program: maintain at 80°C for 0 min, increase to 200°C at a rate of 8°C / min, maintain for 5 min, continue to increase to 300°C at a rate of 30°C / min, and maintain for 7 min.

[0044] Example 1

[0045] 1) Pretreatment of pseudoionone raw materials

[0046] Pt-Rh / Al2O3 was filled into a fixed bed. Under a nitrogen atmosphere, pseudoionone (content 95%, pro-isomer content 3wt%) was passed into the fixed bed for isomerization reaction. The reaction temperature was 60°C and the residence time was maintained for 50 min. At the outlet, samples were taken for gas phase analysis. The pseudoionone content was 98wt%, and the pro-isomer content was 0.008wt%.

[0047] 2) Preparation of α-ionone composition

[0048] Take 500g of pseudoionone treated in step 1) and 400g of n-hexane solvent, pre-mix the two in a glass reactor with mechanical stirring, heat to 80°C, take 150g of 70wt% phosphoric acid aqueous solution, pump it into the reactor through a metering pump, set the flow rate, drip for 1h, and continue the heat preservation cyclization reaction for 3h after the dripping is completed. After the reaction is terminated, stand for 1h, separate the acid phase, then add pure water for washing twice, distill to remove the solvent, perform vacuum distillation, collect the fraction at 140°C / 200PaA, and obtain an α-ionone composition. According to gas chromatography analysis, the α-ionone content is 80wt%, the total ketone content (including α-ionone and isomers such as β-ionone and γ-ionone) is 98wt%, and the impurity A content is 0.007wt%.

[0049] Sensory evaluation of odor: Typical violet floral fragrance, no impurities, pure smell (39.5 points).

[0050] Example 2

[0051] 1) Pretreatment of pseudoionone raw materials

[0052] Pt-Ru / Al2O3 was filled into a fixed bed. Under a nitrogen atmosphere, pseudoionone (content 94.6wt%, pre-isomer content 3.2wt%) was passed into the fixed bed for isomerization reaction. The reaction temperature was 55°C and the residence time was maintained at 80min. At the outlet, samples were taken for gas phase analysis. The pseudoionone content was 98wt%, and the pre-isomer content was 0.007wt%.

[0053] 2) Preparation of α-ionone composition

[0054] Take 1000g of pseudoionone treated in step 1) and 600g of ether solvent, pre-mix the two in a glass reactor with mechanical stirring, heat to 70°C, take 400g of 30wt% sulfuric acid aqueous solution, pump it into the reactor through a metering pump, set the flow rate, drip for 1h, and continue to heat and cyclize for 4h after the dripping is completed. After the reaction is terminated, stand for 1h, separate the acid phase, then add pure water for washing twice, distill to remove the solvent, perform vacuum distillation, collect the fraction at 130°C / 150PaA, and obtain an α-ionone composition. According to gas chromatography analysis, the α-ionone content is 77wt%, the total ketone content (including α-ionone and isomers such as β-ionone and γ-ionone) is 97.5wt%, and the impurity A content is 0.005wt%.

[0055] Sensory evaluation of odor: Typical violet floral fragrance, no impurities, pure smell (39.1 points).

[0056] Example 3

[0057] 1) Pretreatment of pseudoionone raw materials

[0058] Pt-Ir / Al2O3 was filled into a fixed bed. Under a nitrogen atmosphere, pseudoionone (content 94.5wt%, pre-isomer content 3wt%) was passed into the fixed bed for isomerization reaction. The reaction temperature was 50°C and the residence time was maintained at 100min. At the outlet, samples were taken for gas phase analysis. The pseudoionone content was 98wt%, and the pre-isomer content was 0.009wt%.

[0059] 2) Preparation of α-ionone composition

[0060] Take 800g of pseudo-ionone treated in step 1) and 800g of xylene solvent, pre-mix the two in a glass reactor with mechanical stirring, heat to 65°C, take 200g of 50wt% p-toluenesulfonic acid aqueous solution, pump into the reactor through a metering pump, set the flow rate, drip for 1h, and continue to heat and cyclize for 5h after the dripping is completed. After the reaction is terminated, stand for 1h, separate the acid phase, then add pure water for washing twice, distill to remove the solvent, perform vacuum distillation, collect the fraction at 130°C / 150PaA, and obtain an α-ionone composition. According to gas chromatography analysis, the α-ionone content is 85wt%, the total ketone content (including α-ionone and isomers such as β-ionone and γ-ionone) is 98wt%, and the impurity A content is 0.008wt%.

[0061] Sensory evaluation of odor: Typical violet floral fragrance, without any impurities, pure smell (39.6 points).

[0062] Example 4

[0063] 1) Pretreatment of pseudoionone raw materials

[0064] Pt-Ni / Al2O3 was filled into a fixed bed. Under a nitrogen atmosphere, pseudoionone (content 95wt%, pre-isomer content 3wt%) was passed into the fixed bed for isomerization reaction. The reaction temperature was 60°C and the residence time was maintained at 120min. At the outlet, samples were taken for gas phase analysis. The pseudoionone content was 98wt%, and the pre-isomer content was 0.005wt%.

[0065] 2) Preparation of α-ionone composition

[0066] Take 800g of pseudoionone treated in step 1) and 1000g of ether solvent, pre-mix the two in a glass reactor with mechanical stirring, heat to 80°C, take 300g of 30wt% hydrochloric acid aqueous solution, pump it into the reactor through a metering pump, set the flow rate, drip for 1h, and continue to heat and react for 6h after the dripping is completed. After the reaction is terminated, stand for 1h, separate the acid phase, then add pure water to wash twice, distill to remove the solvent, perform vacuum distillation, collect the fraction at 135°C / 180PaA, and obtain an α-ionone composition. According to gas chromatography analysis, the α-ionone content is 83wt%, the total ketone content (including α-ionone and isomers such as β-ionone and γ-ionone) is 98wt%, and the impurity A content is 0.003wt%.

[0067] Sensory evaluation of odor: Typical violet floral fragrance, no impurities, pure smell (39.5 points).

[0068] Comparative Example 1

[0069] Refer to step 2 in Example 1, except that pseudoionone (content 95wt%, pro-isomer content 3wt%) is not pretreated and directly participates in the cyclization reaction to obtain an α-ionone composition. According to gas chromatography analysis, the α-ionone content is 79wt%, the total ketone content (including α-ionone and isomers such as β-ionone and γ-ionone) is 95wt%, and the impurity A content is 2.4wt%.

[0070] Sensory evaluation of odor: The top note of the odor is mixed with ripe fruit aroma, the floral scent is weak, and the smell is acceptable (28.5 points).

[0071] Comparative Example 2

[0072] The α-ionone composition (with a pro-isomer content of 2.4 wt%) prepared in Comparative Example 1 was separated by conventional distillation to reduce the impurity A content in the composition to 0.02 wt%.

[0073] Sensory evaluation of smell: Excellent violet floral fragrance, slightly mixed with other smells, the smell is acceptable (35.5 points).

Claims

1. An alpha-ionone composition, characterized in that It includes ionone and isomers, and impurity A with a content of 0.0001-0.01wt%; wherein the structure of impurity A is shown in Formula 1:

2. A method for preparing the α-ionone composition according to claim 1, characterized in that: The α-ionone composition is prepared by mixing pseudo-ionone with a solvent and then reacting the mixture under the action of an acid catalyst to obtain the α-ionone composition; wherein the content of pseudo-ionone pro-isomer impurities in the pseudo-ionone is controlled to be ≤0.01wt%.

3. The preparation method according to claim 2, characterized in that: The solvent is one or a combination of benzene, toluene, xylene, cumene, tetrahydrofuran, chloroform, ether, anisole, and n-hexane; Preferably, the mass ratio of the pseudoionone to the solvent is 1:0.1-5, more preferably 1:0.5-2.

4. The preparation method according to claim 2, characterized in that: The acid catalyst includes one or more of phosphoric acid, sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid; Preferably, the amount of the acid catalyst is 0.1-1 times the mass of pseudoionone.

5. The preparation method according to claim 2, characterized in that: The cyclization reaction has a reaction temperature of 40-90°C, preferably 50-80°C; and a reaction time of 1-12h, preferably 4-8h.

6. A method for pretreatment based on the pseudoionone principle, characterized in that: The pseudoionone preisomer is converted to pseudoionone by metal-catalyzed isomerization reaction; The content of the pro-isomer impurity is ≤0.01wt%.

7. The method according to claim 6, characterized in that The pseudoionone raw material that can be used for isomerization reaction conversion has a pre-isomer impurity content of >0.01wt%.

8. The method according to claim 6, characterized in that The isomerization reaction method is a metal-catalyzed isomerization reaction; Preferably, the reaction adopts a fixed bed reactor; Preferably, the metal catalyst used in the reaction is one or more of Pt-Rh / Al2O3, Pt-Ru / Al2O3, Pt-Ir / Al2O3, Pt-Pd / Al2O3, Pt-Ni / Al2O3, and Pt-Co / Al2O3.

9. The method according to claim 6, characterized in that The isomerization reaction has a reaction temperature of 30-60°C, preferably 50-60°C; a residence time of 10-300 min, preferably 60-150 min; Preferably, the isomerization reaction is carried out in an inert atmosphere, and the inert atmosphere is selected from one of nitrogen, argon and helium.

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