Method for preparing linalyl acetate

Abstract

The invention discloses a method for preparing linalyl acetate. The method comprises the following steps: step a, preparing linalool of which the content of each component is within a certain range; b, under the action of a catalyst, linalool and acetic anhydride are subjected to an esterification reaction, in the esterification process, the content of active matter needs to be kept at a certain level in the system so as to inhibit generation of oxidized linalool and esterification products of the oxidized linalool, and high-quality linalyl acetate can be obtained. According to the method, the content of key components can be effectively controlled, the purity of the product can be improved, the quality of the product can be improved, particularly, the fragrance retention time of the product can be prolonged, the irritation can be reduced, and the method is more friendly to users.

Description

Technical Field

[0001] The invention belongs to the field of organic chemistry and relates to a synthesis of ester compounds, in particular to a method for preparing linalyl acetate. Background Art

[0002] Linalyl acetate is an important fragrance and chemical intermediate widely used in cosmetics, food, and pharmaceuticals. Its synthesis primarily involves an esterification reaction using linalool and acetic anhydride as raw materials. Because the esterification reaction is relatively mild and highly selective, and the product refining methods are relatively mature, product quality is closely linked to the quality of the raw materials.

[0003] Linalool is obtained by selective hydrogenation of dehydrolinalool. During the hydrogenation process, the degree of hydrogenation needs to be strictly controlled. Insufficient hydrogenation will lead to insufficient conversion of dehydrolinalool, while excessive hydrogenation will increase the proportion of dihydrolinalool. Patents CN201811043834, CN201380032718, and CN00131057 all report on the selective control and improvement of linalool. Although linalool production technology continues to improve, it is still impossible to avoid a small amount of dehydrolinalool remaining in linalool, and it is also difficult to avoid the production of dihydrolinalool. In addition, oxidation products will be generated during the preparation and storage of linalool. The document "Synthesis of Linalool Oxide" Flavors and Fragrances Cosmetics, Supplement in August 2013 pointed out that linalool oxide can be obtained by oxidation of linalool, and its products have two structures: furan type and pyran type:

[0004]

[0005] Dehydrolinalool, dihydrolinalool and linalool oxide are difficult to completely remove from linalool. Therefore, how to effectively control the content of dehydrolinalool, dihydrolinalool and linalool oxide, or to control the content of each component within a certain range, to obtain high-quality linalyl acetate from high-quality linalool, is an urgent problem to be solved in this field. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention proposes a control scheme for linalool and a synthetic method for preparing linalyl acetate.

[0007] In a first aspect, the present invention provides a linalool composition that meets the following requirements:

[0008] 1) The sum of linalool and dihydrolinalool content is greater than 98.5%, and the linalool content is greater than 97.5%;

[0009] 2) the sum of the contents of dehydrolinalool and dihydrolinalool is 0.5%-1%, and the content of dihydrolinalool is greater than the content of dehydrolinalool;

[0010] 3) The content of linalool oxide is less than 0.1%, and the furan oxide is greater than the pyran oxide.

[0011] In some specific embodiments of the present invention, in the composition, the sum of the contents of linalool and dihydrolinalool is greater than 98.5%, for example, 98.8%, 99%, 99.2%, 99.5%, etc.; and the linalool content is greater than 97.5%, for example, 97.8%, 98%, 98.5%, 99%, etc.; preferably, the sum of the contents of linalool and dihydrolinalool is greater than 99%, and the linalool content is greater than 98%;

[0012] In some specific embodiments of the present invention, in the composition, the sum of the contents of dehydrolinalool and dihydrolinalool is 0.5%-1%, for example, 0.6%, 0.8%, etc., wherein the content of dihydrolinalool is, for example, 0.45%, 0.6%, 0.7%, 0.8%, 0.85%, 0.9%, etc., and the content of dehydrolinalool is, for example, 1 ppm, 3 ppm, 0.01%, 0.05%, 0.1%, etc.;

[0013] In some specific embodiments of the present invention, in the composition, the content of linalool oxide (the sum of the content of furan type and pyran type) is less than 0.1%, for example, 0.01%, 0.03%, 0.05%, 0.08%, etc.; preferably, the content of linalool oxide (the sum of the content of furan type and pyran type) is greater than 0.01%.

[0014] There are no specific requirements for the method of obtaining the linalool composition. For example, by optimizing reaction conditions during the preparation process and controlling the dehydrolinalool, dihydrolinalool, and linalool oxide content of the linalool within a certain range through post-processing, linalyl acetate synthesized using linalool that meets these standards has a high-quality and elegant aroma, improving product quality, particularly by extending the product's fragrance lifespan and reducing irritation, making it more readily accepted by consumers.

[0015] In a specific embodiment of the present invention, metal ions and an active substance are added to the linalool reaction solution and then subjected to vacuum distillation. The addition of metal ions effectively decomposes dehydrolinalool, thereby achieving the purpose of controlling the dehydrolinalool content in linalool. The principle is that dehydrolinalool decomposes into acetylene and methyl heptenone under the action of specific metal ions. The boiling points of acetylene and methyl heptenone are significantly different from those of linalool, making them easy to separate from linalool, thereby achieving the purpose of reducing the dehydrolinalool content in linalool. The addition of the active substance can inhibit the formation of linalool oxide, and the active substance and metal ion complexation form a complex that can convert pyranyl linalool oxide into furanyl oxide. In addition, the content of dihydrolinalool is controlled by, on the one hand, controlling the degree of partial hydrogenation in the linalool synthesis step to avoid the generation of a large amount of dihydrolinalool, and on the other hand, controlling the distillation conditions during the distillation of the linalool reaction liquid. The boiling point of dihydrolinalool is higher than that of linalool. When the level of dihydrolinalool is relatively low, the dihydrolinalool content in linalool can be controlled within a certain range through fine fractionation.

[0016] The linalool reaction solution refers to a reaction solution obtained by selective hydrogenation of dehydrolinalool, the linalool content is 10-100%, and the solvent can be methanol, ethanol, water, toluene, n-hexane, etc., or no solvent is used. The preparation process of the reaction solution can refer to the following literature or patent methods: [1] Semihydrogenation of acetylenes: Modifiedlindlar catalyst [J]. Tetrahedron 1983, 39 (13): 2315-2322. [2] Structure and Properties of Bimetallic Colloids Formed in Polystyrene-block-Poly-4-vinylpyridine Micelles: Catalytic Behavior in Selective Hydrogenation of Dehydrolinalool [J]. Journal of Catalysis 2000 196: 302-314. [3] Synthesis of linalool over Ph and Bi modified Pd catalysts [J]. Fine Chemicals, 2003, 20 (8): 481-483. [4] Research on selective hydrogenation reaction in the synthesis of linalool. Master of Engineering thesis, Zhejiang University of Technology.

[0017] In some specific embodiments of the present invention, the metal ions are selected from zinc, magnesium, aluminum, and iron ions, and these ions can be added to the system in the form of metal salts, such as zinc acetate, magnesium sulfate, aluminum carbonate, iron acetate, etc., preferably zinc acetate;

[0018] Based on the mass of the linalool reaction solution, preferably, the added amount of the metal ions is 5-500 ppm, preferably 10-200 ppm.

[0019] In some specific embodiments of the present invention, the active substance is one or a combination of tocopherol, tocopherol acetate, tocopherol palmitate, vitamin A, carotene, and chlorophyll, preferably tocopherol;

[0020] Based on the mass of the linalool reaction solution, preferably, the amount of the active substance added is 100-500 ppm, preferably 200-300 ppm.

[0021] In some specific embodiments of the present invention, the reaction solution is subjected to vacuum distillation at a temperature of 80-150° C., preferably 90-120° C., and an absolute pressure of 0.1-10 KPa, preferably 0.1-0.5 KPa. The contents of dehydrolinalool and dihydrolinalool in linalool are reduced by vacuum distillation such that the sum of the contents of dehydrolinalool and dihydrolinalool is 0.5%-1%, and the content of dihydrolinalool is greater than that of dehydrolinalool.

[0022] In another aspect, the present invention provides a method for preparing linalyl acetate, comprising:

[0023] Under the action of a catalyst, the aforementioned linalool composition and acetic anhydride undergo an esterification reaction to obtain linalyl acetate.

[0024] In one embodiment of the present invention, the system needs to maintain an active ingredient content at a certain level during the esterification process to inhibit the formation of linalool oxide. The active ingredient is one or a combination of tocopherol, tocopheryl acetate, tocopheryl palmitate, vitamin A, carotene, and chlorophyll, preferably tocopherol.

[0025] Preferably, the amount of the active ingredient is 0.01-0.1%, preferably 0.02-0.03%, by mass of the linalool composition.

[0026] In one embodiment of the present invention, the catalyst is one or more of 4-dimethylaminopyridine, sodium carbonate, potassium acetate, potassium hydroxide, trioctyl ammonium, triethanolamine, 1,8-diazabicycloundec-7-ene, sulfuric acid, p-toluenesulfonic acid, and methanesulfonic acid, preferably 4-dimethylaminopyridine;

[0027] Preferably, the amount of the catalyst is 0.5-5%, preferably 1-3%, by mass of the linalool composition.

[0028] In one embodiment of the present invention, the molar ratio of acetic anhydride to linalool is (1-3):1, preferably (1.1-2):1.

[0029] In one embodiment of the present invention, the esterification reaction temperature is 60-130°C, preferably 80-110°C, and the reaction time is 2-24 hours, preferably 3-8 hours. To promote the reaction toward the production of linalyl acetate, the reaction can be carried out under reduced pressure to remove the generated acetic acid. The reaction pressure (absolute pressure) is 0.51-30 kPa, preferably 1-10 kPa.

[0030] The beneficial effects of the present invention are:

[0031] The present invention effectively decomposes dehydrolinalool by adding specific metal ions to the distillation of a linalool reaction solution, thereby achieving the purpose of controlling the dehydrolinalool content in linalool. The addition of an active substance can inhibit the formation of linalool oxide. The complex formed by the active substance and the metal ion converts pyranyl linalool oxides, which have poor odor quality, into furanyl linalool oxides, which have no negative impact on the main aroma.

[0032] By controlling specific components, the quality of linalool, and thus linalyl acetate, is improved. This solution can enhance the product's fragrance longevity, reduce irritation, and make it more user-friendly.

[0033] The method of the present invention is simple and easy to implement, does not affect the efficiency and selectivity of the reaction, and therefore does not lead to a decrease in the yield of linalyl acetate. The method is more practical and operable. DETAILED DESCRIPTION

[0034] The present invention will be further described below through specific examples. The examples of the present invention are only for illustration of the present invention and do not limit the scope of the present invention.

[0035] Main raw material information:

[0036] Acetic anhydride: purity ≥99%, Inokai Technology Co., Ltd.

[0037] 4-Dimethylaminopyridine: purity 99%, Inokai Technology Co., Ltd.

[0038] Zinc acetate: purity 99%, Inokai Technology Co., Ltd.

[0039] Tocopherol: purity 97%, Inokai Technology Co., Ltd.

[0040] The main test methods involved in the following examples are as follows:

[0041] Gas chromatograph: Gas chromatograph: Agilent7890B, chromatographic column model / stationary phase HP-VOC / 6% cyanopropylphenyl-methylpolysiloxane, column length / m 60, column inner diameter / mm 0.32, liquid film thickness / μm 1.8, carrier gas nitrogen, carrier gas flow rate / (mL / min) 1.5, column temperature initial temperature 100℃ maintained for 5min, then increased to 200℃ at 15℃ / min and maintained for 10min, then increased to 270℃ at 5℃ / min and maintained for 5min, vaporizer temperature / ℃270, detector temperature / ℃280, injection volume / μL 1.0, split ratio 30:1, hydrogen flow rate / (mL / min)40, air flow rate / (mL / min)400, makeup gas flow rate / (mL / min)30.

[0042] Smell and fragrance lingering test method: Prepare fragrance paper and fragrance ingredients. First, dip a small amount of fragrance ingredient into each piece of fragrance paper. Then, hold each piece of fragrance paper to your nose and smell it, recording the feeling and odor intensity of each fragrance. After the fragrance paper is placed for a period of time, smell it again, recording the feeling and odor intensity of each fragrance, and evaluate the fragrance's persistence and changes.

[0043] The aroma quality was evaluated using: (i) odor intensity on a scale of 0 to 10 (where 0 = none, 1 = very weak, 5 = moderate, and 10 = very strong); and (ii) complexity (where 0 = none, 1 = very low, 5 = moderate, and 10 = very high). Each test required at least three testers to participate and provide scores for each item, and the average score was taken as the test value for that item.

[0044] Skin irritation test method: Referring to SN / T 3948-2014 "In vitro skin irritation of chemicals: reconstituted human epidermis test", a human epidermal model was used. Human keratinocytes were cultured in vitro and fully differentiated into a three-dimensional human epidermal model with a multi-layered skin structure. The test substance was applied to the skin model, and after a certain exposure time, the cell viability was measured using the MTT assay. The test concentration was 50 mg / cm 2 , obtain half effective time (ET 50 ) is used as the basis for evaluating the degree of skin irritation. In this scheme, the half-effective time is defined as the time required for cell activity to decrease by 50% at a certain concentration.

[0045] Preparation of Linalool in Preliminary Example

[0046] Under an inert gas atmosphere, 5000.0 g of ethanol and 25.0 g of a 5% Pd-5% Pb palladium-calcium carbonate catalyst were added to the autoclave. The autoclave was sealed and replaced with hydrogen six times, ultimately maintaining a hydrogen pressure of 2.0 MPa (gauge pressure), and stirring was started.

[0047] Heat the autoclave to 60°C. Add 5000.0 g of dehydrolinalool to the autoclave using a horizontal flow pump. After the addition of dehydrolinalool is complete, maintain the autoclave temperature at 60°C and continue the reaction. After 2 hours of reaction, when the hydrogen flowmeter on the inlet line indicates a flow rate below 0.5 mL / min, stop stirring and vent the hydrogen from the autoclave. GC analysis of the reaction solution reveals the following composition (excluding ethanol): 98.21% linalool, 0.83% dihydrolinalool, 0.67% dehydrolinalool, and the remainder being other components.

[0048] Example 1 Linalool Refining-1

[0049] 500g of the linalool reaction solution was added to the bottom of a distillation tower, and ethanol was removed by distillation at a pressure of 20kPa (absolute pressure) and a bottom temperature of 82-85°C. The distillation tower had 15 theoretical plates and a reflux ratio of 3:1. After no more ethanol was produced from the top of the tower, the pressure was changed to 1.5kPa absolute pressure, the bottom temperature was raised to 109-112°C, and the component with a top temperature of 90-92°C was collected. The composition of the sample was analyzed by gas chromatography (GC): 98.31% linalool, 0.72% dihydrolinalool, 0.63% dehydrolinalool, 0.05% linalool furan oxide, 0.12% linalool pyran oxide, and the remainder was other components.

[0050] Example 2 Linalool Refining-2

[0051] 500g of the linalool reaction solution was added to the bottom of a distillation tower, and ethanol was removed by distillation at a pressure of 20kPa (absolute pressure) and a bottom temperature of 82-85°C. The distillation tower had 25 theoretical plates and a reflux ratio of 2:1. After no more ethanol was produced from the top of the tower, the pressure was changed to 1.0kPa absolute pressure and the reflux ratio was adjusted to 5:1. The bottom temperature was raised to 98-101°C, and the components with a top temperature of 85-86°C were collected and analyzed by gas chromatography (GC). The composition showed: 99.42% linalool, 0.13% dihydrolinalool, 0.06% dehydrolinalool, 0.09% linalool furan oxide, 0.22% linalool pyran oxide, and the remainder being other components.

[0052] Example 3 Linalool Refining-3

[0053] 1000g of linalool reaction solution, 0.04g of zinc acetate, and 0.12g of tocopherol were added to the bottom of a distillation tower. Ethanol was distilled at 20kPa (absolute pressure) and a bottom temperature of 82-85°C to remove ethanol. The distillation tower had 15 theoretical plates and a reflux ratio of 3:1. After no more ethanol was produced from the top of the tower, the pressure was changed to 1.5kPa absolute, the bottom temperature was raised to 109-112°C, and methyl heptenone, a decomposition product of dehydrolinalool, was collected from the top of the tower. Collection was continued until the top temperature rose to 90°C. The component with a top temperature of 90-91°C was collected and analyzed by gas chromatography (GC). The composition showed 98.92% linalool, 0.79% dihydrolinalool, 17ppm dehydrolinalool, 0.07% linalool furan oxide, 0.01% linalool pyran oxide, and the remainder being other components.

[0054] Example 4 Linalool Refining-4

[0055] 500g of the linalool reaction solution, 0.05g of zinc acetate, and 0.15g of tocopherol were added to the bottom of a distillation tower. Ethanol was distilled at 20kPa absolute pressure and a bottom temperature of 82-85°C to remove the ethanol. The distillation tower had 25 theoretical plates and a reflux ratio of 3:1. After no more ethanol was produced at the top of the tower, the pressure was lowered to 1.0kPa absolute and the reflux ratio was adjusted to 2:1. The bottom temperature rose to 98-101°C, and methyl heptenone, a decomposition product of dehydrolinalool, was collected from the top of the tower. Collection continued until the top temperature rose to 85°C. The component at the top of the tower at 85-86°C was collected and analyzed by gas chromatography (GC). The composition showed 99.17% linalool, 0.62% dihydrolinalool, 3ppm dehydrolinalool, 0.03% linalool furan oxide, 0.01% linalool pyran oxide, and the remainder was other components.

[0056] Example 5 Linalool Refining-5

[0057] 500g of the linalool reaction solution, 0.25g of aluminum carbonate, and 0.20g of tocopheryl palmitate were added to the bottom of a distillation tower. Ethanol was distilled at 20kPa (absolute pressure) and a bottom temperature of 82-85°C to remove the ethanol. The distillation tower had 15 theoretical plates and a reflux ratio of 3:1. After no more ethanol was produced from the top of the tower, the pressure was reduced to 1.5kPa absolute, and the bottom temperature was raised to 109-112°C. Methyl heptenone, a decomposition product of dehydrolinalool, was collected from the top of the tower. Collection was continued until the top temperature rose to 90°C. The component with a top temperature of 90-92°C was collected and analyzed by gas chromatography (GC). The composition showed 99.07% linalool, 0.81% dihydrolinalool, 0.02% dehydrolinalool, 0.06% linalool furan oxide, 0.03% linalool pyran oxide, and the remainder being other components.

[0058] Example 6 Linalool Refining-6

[0059] 500g of the linalool reaction solution, 0.10g of magnesium sulfate, and 0.15g of tocopheryl acetate were added to the bottom of a distillation column. Ethanol was distilled at 20kPa absolute pressure and a bottom temperature of 82-85°C to remove the ethanol. The distillation column had 15 theoretical plates and a reflux ratio of 3:1. After no more ethanol was produced at the top of the column, the pressure was adjusted to 1.0kPa absolute and the reflux ratio was adjusted to 1:1. The bottom temperature was raised to 98-101°C, and methyl heptenone, a decomposition product of dehydrolinalool, was collected from the top of the column. Collection was continued until the top temperature rose to 85°C. The component at the top of the column at 85-86°C was collected and analyzed by gas chromatography (GC). The composition showed 98.78% linalool, 0.81% dihydrolinalool, 0.03% dehydrolinalool, 0.05% linalool furan oxide, 0.02% linalool pyran oxide, and the remainder being other components.

[0060] Example 7 Synthesis of Linalyl Acetate-1

[0061] 204g of acetic anhydride, 154g of linalool purified by the method of Example 3 (with 0.04g of tocopherol added), and 2.00g of 4-dimethylaminopyridine were added to the bottom of a distillation column and reacted at a pressure of 15kPa (absolute pressure) and a temperature of 85-89°C in the bottom of the column. The distillation column had 15 theoretical plates and a reflux ratio of 3:1. Acetic acid was extracted from the top of the column during the reaction. The total reaction time was 6h. The pressure was changed to an absolute pressure of 1.0kPa, and a mixture of acetic acid and acetic anhydride was extracted from the top of the column. The sample was collected until the top temperature rose to 87°C. The components with a top temperature of 87-88°C were collected and analyzed by gas chromatography (GC). The composition showed that the content of linalyl acetate was 98.96%, the content of dihydrolinalyl acetate was 0.62%, the content of dehydrolinalyl acetate was not detected, the content of linalool furan oxide acetate was 0.05%, the content of linalool pyran oxide acetate was not detected, and the remainder was other components.

[0062] The linalyl acetate odor intensity of this batch is 9.0, the fragrance lasts for 5-6 hours, and the complexity level is 9.0. The above evaluation shows that this batch of products has excellent odor intensity and fragrance lasting time, and has a high complexity of odor properties.

[0063] The half effective time (ET50) is 48-50h.

[0064] Example 8 Synthesis of Linalyl Acetate-2

[0065] 204g of acetic anhydride, 154g of linalool purified by the method of Example 4 (with 0.03g of tocopherol added), and 2.00g of 4-dimethylaminopyridine were added to the bottom of a distillation column and reacted at a pressure of 15kPa (absolute pressure) and a temperature in the bottom of the column of 85-89°C. The distillation column had 15 theoretical plates and a reflux ratio of 3:1. Acetic acid was removed from the top of the column during the reaction. The total reaction time was 6h. The pressure was changed to an absolute pressure of 1.0kPa, and a mixture of acetic acid and acetic anhydride was removed from the top of the column. Collection was continued until the top temperature rose to 87°C. The component with a top temperature of 87-88°C was collected and analyzed by gas chromatography (GC). The composition showed that the content of linalyl acetate was 99.34%, the content of dihydrolinalyl acetate was 0.37%, the content of dehydrolinalyl acetate was not detected, the content of linalool furanyl oxide acetate was 0.01%, the content of linalool pyranyl oxide acetate was not detected, and the remainder was other components.

[0066] The linalyl acetate odor intensity of this batch is 9.5, the fragrance lasts for 5-6 hours, and the complexity level is 9.5. The above evaluation shows that this batch of products exhibits excellent odor intensity and fragrance lasting time, and has extremely complex odor properties.

[0067] The half effective time (ET50) is 54-60h.

[0068] Example 9 Synthesis of Linalyl Acetate-3

[0069] 204 g of acetic anhydride, 154 g of linalool purified using the method of Example 5 (with 0.123 g of tocopheryl palmitate added), and 2.00 g of 4-dimethylaminopyridine were added to the bottom of a distillation column and reacted at a pressure of 15 kPa (absolute pressure) and a bottom temperature of 85-89°C. The distillation column had 15 theoretical plates and a reflux ratio of 3:1. Acetic acid was removed from the top of the column during the reaction. The total reaction time was 6 h. The pressure was then changed to 1.0 kPa absolute pressure, and a mixture of acetic acid and acetic anhydride was removed from the top of the column. Collection was continued until the top temperature rose to 87°C. The fraction at the top temperature of 87-88°C was collected and analyzed by gas chromatography (GC). The composition showed 99.23% linalyl acetate, 0.58% dihydrolinalyl acetate, 0.01% dehydrolinalyl acetate, 0.05% linalool furanyl oxide acetate, 0.02% linalool pyranyl oxide acetate, and the remainder being other components.

[0070] The linalyl acetate odor intensity of this batch is 8.5, the fragrance lasts for 4-5 hours, and the complexity level is 8.5. The above evaluation shows that this batch of products has good odor intensity and fragrance lasting time, and has a high complexity of odor properties.

[0071] The half effective time (ET50) is 38-42h.

[0072] Example 10 Synthesis of Linalyl Acetate-4

[0073] 204 g of acetic anhydride, 154 g of linalool purified by the method of Example 6 (with 0.046 g of tocopheryl acetate added), and 2.00 g of 4-dimethylaminopyridine were added to the bottom of a distillation column and reacted at a pressure of 15 kPa (absolute pressure) and a temperature in the bottom of the column of 85-89 ° C. The distillation column had 15 theoretical plates and a reflux ratio of 3:1. Acetic acid was withdrawn from the top of the column during the reaction. The total reaction time was 6 h. The pressure was changed to an absolute pressure of 1.0 kPa, and a mixture of acetic acid and acetic anhydride was withdrawn from the top of the column. Collection was continued until the top temperature rose to 87 ° C. The component with a top temperature of 87-88 ° C was collected and sampled for gas chromatography (GC) analysis. The composition showed: 99.02% linalyl acetate, 0.53% dihydrolinalyl acetate, 0.01% dehydrolinalyl acetate, 0.02% linalool furanyl oxide acetate, 0.01% linalool pyranyl oxide acetate, and the remainder was other components.

[0074] The linalyl acetate odor intensity of this batch is 8.5, the fragrance lasts for 4-5 hours, and the complexity level is 9.0. The above evaluation shows that this batch of products has good odor intensity and fragrance lasting time, and has a high complexity of odor properties.

[0075] The half effective time (ET50) is 44-47h.

[0076] Comparative Example 1

[0077] Linalyl acetate was prepared according to the method of Example 7, except that the linalool purified by the method of Example 1 was used, and 0.04 g of tocopherol was added. Gas chromatography (GC) analysis of the sample revealed a composition of 98.33% linalyl acetate, 0.68% dihydrolinalyl acetate, 0.62% dehydrolinalyl acetate, 0.05% linalool furanyl oxide acetate, 0.12% linalool pyranyl oxide acetate, and the remainder consisting of other components.

[0078] This batch of linalyl acetate has an odor intensity of 6.5, a longevity of 4-5 hours, and a complexity level of 8.0. The above evaluation shows that this batch of products has a medium to weak odor intensity, good longevity, and a high complexity of odor properties.

[0079] Half effective time (ET50) 20h-23h.

[0080] Comparative Example 2

[0081] Linalyl acetate was prepared according to the method of Example 7, except that the linalool was purified using the method of Example 2 and did not contain tocopherol. Gas chromatography (GC) analysis of the sample revealed a composition of 99.43% linalyl acetate, 0.07% dihydrolinalyl acetate, 0.02% dehydrolinalyl acetate, 0.09% linalool furanyl oxide acetate, 0.27% linalool pyranyl oxide acetate, and the remainder consisting of other components.

[0082] The linalyl acetate odor intensity of this batch is 7.5, the fragrance lasts for 3-4 hours, and the complexity level is 7.5. The above evaluation shows that this batch of products has medium odor intensity and fragrance lasting time, and has a high complexity of odor properties.

[0083] The half effective time (ET50) is 16-18h.

[0084] Comparative Example 3

[0085] Linalyl acetate was prepared according to the method of Example 7, except that linalool did not contain tocopherol. Gas chromatography (GC) analysis of the sample revealed 98.92% linalyl acetate, 0.63% dihydrolinalyl acetate, 0.02% dehydrolinalyl acetate, 0.11% linalool furanyl oxide acetate, 0.04% linalool pyranyl oxide acetate, and the remainder being other components.

[0086] The linalyl acetate odor intensity of this batch is 8.5, the fragrance lasts for 4-5 hours, and the complexity level is 8.5. The above evaluation shows that this batch of products has strong odor intensity and fragrance lasting time, and has a high complexity of odor properties.

[0087] The half effective time (ET50) is 24-27h.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be considered within the scope of protection of the present invention.

Claims

1. A linalool composition, which meets the following requirements: 1) The sum of linalool and dihydrolinalool content is greater than 98.5%, and the linalool content is greater than 97.5%; 2) the sum of the contents of dehydrolinalool and dihydrolinalool is 0.5%-1%, and the content of dihydrolinalool is greater than the content of dehydrolinalool; 3) The content of linalool oxide is less than 0.1%, and the furan oxide is greater than the pyran oxide.

2. The linalool composition according to claim 1, wherein The sum of the contents of linalool and dihydrolinalool is greater than 99%, and the linalool content is greater than 98%; the linalool oxide content is greater than 0.01%.

3. A method for preparing the linalool composition according to claim 1 or 2, comprising adding metal ions and an active substance to the linalool reaction solution and performing vacuum distillation.

4. The method according to claim 3, wherein: The metal ions are selected from zinc, magnesium, aluminum, and iron ions; Preferably, based on the mass of the linalool reaction solution, the amount of metal ions added is 5-500 ppm.

5. The method according to claim 3, wherein The active ingredient is one or more of tocopherol, tocopheryl acetate, tocopheryl palmitate, vitamin A, carotene, and chlorophyll; Preferably, based on the mass of the linalool reaction solution, the amount of the active substance added is 100-500 ppm.

6. The method according to any one of claims 3 to 5, wherein: The temperature of vacuum distillation is 80-150°C, and the absolute pressure is 0.1-10KPa.

7. A method for preparing linalyl acetate, comprising: Under the action of a catalyst, the linalool composition according to claim 1 or 2 and acetic anhydride are subjected to an esterification reaction to obtain linalyl acetate.

8. The method according to claim 7, wherein: Active substances are added during the esterification process, wherein the active substances are selected from tocopherol, tocopherol acetate, tocopherol palmitate, vitamin A, carotene, and chlorophyll; Preferably, the amount of the active ingredient is 0.01-0.1%, preferably 0.02-0.03%, by mass of the linalool composition.

9. The method according to claim 7, wherein: The catalyst is selected from 4-dimethylaminopyridine, sodium carbonate, potassium acetate, potassium hydroxide, trioctyl ammonium, triethanolamine, 1,8-diazabicycloundec-7-ene, sulfuric acid, p-toluenesulfonic acid, and methanesulfonic acid; Preferably, the amount of the catalyst is 0.5-5%, preferably 1-3%, by mass of the linalool composition.

10. The method according to claim 7, wherein: The molar ratio of acetic anhydride to linalool is (1-3):1, preferably (1.1-2):1; Preferably, the esterification reaction temperature is 60-130° C., preferably 80-110° C., the reaction time is 2-24 h, preferably 3-8 h; and the absolute reaction pressure is 0.51-30 KPa, preferably 1-10 KPa.

Images