A method for preparing linalool

Abstract

The application relates to the chemical technology field and discloses a preparation method of linalool. According to the preparation method, a proper amount of an additive containing Zn, Co and Fe elements is added in dehydro-linalool as a reaction raw material, so that the catalytic characteristics of a catalyst in a hydrogenation reaction process can be broken through, the hydrogenation degree of the raw material is controlled, a certain amount of by-product dihydro-linalool and ring dehydro-linalool capable of regulating fragrance can be generated, and the linalool product prepared according to the application has more transparent fragrance and improved product quality through professional fragrance tester testing. Meanwhile, before rectification and refining of a hydrogenation reaction liquid, the reaction liquid is washed with an alkali solution to carry out deacidification treatment, so that the dehydration of linalool in the rectification process can be inhibited, and the product purity and qualified product yield are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical technology field, in particular to a preparation method of linalool. BACKGROUND

[0002] As an important perfume variety, whether the aroma of linalool is pure is the most important indicator for evaluating the quality of linalool. The aroma of linalool obtained by different processes is quite different. Linalool with poor aroma can only be applied to the detergent industry, while linalool with better aroma can be used in high value-added fields such as perfume and fragrance. Therefore, producing more competitive linalool products has become the goal universally pursued in the field.

[0003] At present, the production process of linalool mainly adopts a batch kettle process, in which dehydro-linalool is used as raw material, Pd / CaCO3 is used as catalyst, and hydrogen is reacted to obtain linalool. The batch kettle process not only has low production efficiency, but also the raw material will be converted into linalool and dihydro-linalool with high content under the action of the catalyst. In order to adjust the aroma of the product, other perfumes need to be artificially added to the product for aroma adjustment during post-processing, resulting in complex process, high cost, and unstable aroma of each batch of products. Therefore, how to directly generate appropriate by-products to adjust the aroma during the hydrogenation reaction of dehydro-linalool is a technical problem to be solved by those skilled in the art. SUMMARY

[0004] Therefore, the present application provides a preparation method of linalool to solve the problem that the existing process needs to adjust the aroma of the product, resulting in a complex process and unstable aroma of each batch of products.

[0005] According to the embodiments of the present application, a preparation method of linalool is provided, which comprises the following steps:

[0006] S1, uniformly mixing dehydro-linalool and an additive to form a raw material mixture;

[0007] The additive comprises a compound containing at least one of Zn, Co and Fe elements, and the mass ratio of the additive to the dehydro-linalool is 0.001%-0.005%;

[0008] S2, under the action of a catalyst, the raw material mixture is reacted with hydrogen in a solvent to obtain a reaction liquid after the reaction is completed;

[0009] S3, washing the reaction liquid with an alkali solution, collecting an organic phase, and performing rectification treatment on the organic phase to collect a rectification tower overhead fraction.

[0010] It should be noted that the existing linalool production process generally pursues high purity of linalool to avoid short fragrance retention time, light and floating fragrance, and single tailing of linalool product. However, the present application research finds that the fragrance of linalool product is not the result of a single substance, but is jointly affected by the purity of the main product and the content of key impurities. If the purity of linalool in the linalool product is very high, the content of key impurities such as dihydro linalool is correspondingly less, which will lead to the linalool product with heavy fragrance, and additional addition of other spices is needed to adjust the fragrance.

[0011] Therefore, the present application proposes a preparation method of linalool. By adding a certain amount of additives containing Zn, Co and Fe elements in the reaction raw material dehydro linalool, the metal elements in these additives can strongly bind to the active sites on the catalyst, inhibit part of the activity of the catalyst, break through the catalytic characteristics of the catalyst in the hydrogenation reaction process, control the hydrogenation degree of the raw material, and generate a certain amount of by-products dihydro linalool and ring dehydro linalool (structural formula shown below) which can regulate the fragrance. After testing by professional fragrance testers, the linalool product prepared by the present application has more transparent fragrance, and the product quality is improved. If the content of the additive is too high, it will affect the activity of the catalyst, resulting in that the conversion rate of the raw material and the yield of the product cannot meet the requirements. On the contrary, if the content of the additive is too low, a certain amount of dihydro linalool and ring dehydro linalool by-products cannot be generated, which affects the fragrance of the product.

[0012]

[0013] Ring dehydro linalool structural formula

[0014] At the same time, the present application research finds that in the separation and purification process of linalool product, due to the high boiling point of linalool itself, even at low pressure, the temperature of the tower kettle is still very high, and the additive containing Zn, Co and Fe elements is a Lewis acid which can catalyze the dehydration reaction of linalool at high temperature (dehydration side reaction shown in the formula below), and the dehydration by-product is not easy to separate due to its similar boiling point with linalool, resulting in that the product purity does not meet the requirements, and the yield of qualified products is only 20%-30%. In view of this, the present application washes the reaction liquid with alkali solution to remove acid before rectifying and purifying the hydrogenation reaction liquid, which can inhibit the dehydration of linalool in the rectification process, thereby improving the product purity and the yield of qualified products.

[0015]

[0016] In some optional embodiments, the mass ratio of the additive to the dehydro linalool is 0.002%-0.004%. The additive amount in this range can better balance the balance between the activity of the catalyst and the content of the by-products (dihydro linalool and ring dehydro linalool).

[0017] In some alternative embodiments, the assistant includes at least one of a phosphate or acetate of Zn, Co, Fe. The present application has found that the phosphate or acetate of Zn, Co, Fe has good solubility in the reaction solvent, and can be uniformly dispersed in the reaction system, so as to better combine with the active sites of the catalyst. Thus, a small amount of the assistant can achieve the effect of inhibiting the partial activity of the catalyst. For example, the assistant includes at least one of zinc phosphate, iron phosphate, ferrous phosphate, cobalt phosphate, zinc acetate, iron acetate, ferrous acetate or cobalt acetate.

[0018] Further, in order to solve the problem of low production efficiency caused by the batch tank process in the existing linalool production process, in some alternative embodiments, S2 is carried out in a fluidized bed reactor, including the following steps: loading the catalyst and the solvent into the fluidized bed reactor, sealing, and continuously feeding hydrogen into the fluidized bed reactor to ensure that the catalyst is in a fluidized state; then, slowly pumping the raw material mixture into the fluidized bed reactor for reaction, and controlling the reaction temperature to be 40-120°C and the reaction pressure to be 1-5 MPa.

[0019] The present application uses a fluidized bed reactor for hydrogenation reaction, which can ensure the continuous reaction and improve the production efficiency. Controlling the reaction temperature and pressure in the above range can ensure the smooth progress of the reaction, improve the purity of linalool, and obtain a certain amount of by-products dihydro linalool and ring dehydro linalool, and improve the product aroma.

[0020] Further, by controlling the reaction temperature to be 50-100°C and the reaction pressure to be 2-4 MPa, the aroma of linalool product can be better guaranteed, so that it can be applied in high-end fields.

[0021] In some alternative embodiments, the feeding rate of the raw material mixture is 1-5 mL / min. Controlling the slow entry of the raw material into the reactor can ensure the complete conversion of the raw material in the reactor, avoid the residue of the raw material, and also avoid the violent heat release of the reaction to prevent the reaction from overheating.

[0022] It can be understood that, in order to ensure that the reaction raw material dehydro linalool can fully contact with hydrogen, and promote the hydrogenation reaction, it is also necessary to reasonably control the amount of the solvent. In some alternative embodiments, the mass ratio of the solvent to the dehydro linalool is 0.5-3:1, and particularly 0.5-1.5:1. On the one hand, it can ensure the smooth progress of the hydrogenation reaction, and on the other hand, it can also dilute the reaction system, avoid the violent heat release of the hydrogenation reaction, and prevent the reactor from causing safety accidents due to the inability to timely remove heat.

[0023] Exemplarily, the solvent comprises at least one of pure water, aliphatic alkane, aromatic hydrocarbon, ether, alcohol, which does not react with dehydro-linalool, for example, at least one of ethanol, methanol, n-heptane or toluene.

[0024] The catalyst dosage has a great influence on the hydrogenation effect. The present application finds that when the mass ratio of the catalyst to the dehydro-linalool is 0.005-0.03:1, especially 0.01-0.02:1, the raw material conversion can be ensured, and the accumulation of the raw material in the reaction liquid can be avoided, thereby affecting the purity and aroma of the linalool product.

[0025] Exemplarily, the catalyst comprises at least one of Ni / SiO2, Ni / Al2O3, Pd / CaCO3, so that the partial hydrogenation conversion of dehydro-linalool to linalool can be realized. It can be understood that in the representation of the catalyst, the substance before " / " represents the active component of the catalyst, and the substance after " / " represents the carrier of the catalyst.

[0026] In some optional embodiments, the alkali solution is an aqueous solution of alkali metal hydroxide, and the content of the alkali metal hydroxide is 3%-10% based on the mass of the alkali solution, so that the acidic sites of the catalyst can be adjusted, and the dehydration side reaction of the product during the rectification process can be avoided. Exemplarily, the alkali metal hydroxide comprises at least one of NaOH and KOH.

[0027] In some optional embodiments, when the mass ratio of the alkali metal hydroxide to the dehydro-linalool is 0.005-0.025, especially 0.01-0.02, the acidic sites of the catalyst can be better adjusted, so that the excessive dehydration side reaction of the product during the rectification process can be avoided.

[0028] In some optional embodiments, the alkali solution and the reaction liquid undergo a neutralization reaction, the reaction temperature is 50°C-90°C, and the reaction time is 10 min-50 min. Especially when the reaction temperature is 60°C-80°C and the reaction time is 20 min-40 min, the acidic sites of the catalyst can be better adjusted, so that the excessive dehydration side reaction of the product during the rectification process can be avoided.

[0029] In some optional embodiments, the bottom temperature of the rectification tower is 130°C-170°C, the top temperature is 80°C-130°C, the internal pressure of the tower is 10 Pa-500 Pa, and the theoretical tray number of the rectification tower is 15-25. In this way, the product can be refined, so that a qualified linalool product can be obtained.

[0030] Further, when the bottom temperature of the rectifying tower is 140-160℃, the top temperature is 85-110℃, the pressure in the tower is 10-100Pa, and the number of theoretical plates is 15-20, a product with higher purity can be obtained, thus obtaining a better aroma.

[0031] In some alternative embodiments, the overhead fraction comprises >96% linalool, 0.01-2% dihydro-linalool, and >2% cyclodi-hydro-linalool, based on the total mass of the overhead fraction. Further, the overhead fraction comprises 96.1-97% linalool, 0.6-1.2% dihydro-linalool, and 2.1-2.7% cyclodi-hydro-linalool.

[0032] In the presence of appropriate amounts of dihydro-linalool and cyclodi-hydro-linalool, the aroma of the linalool product is more transparent, and the product also has a long-lasting aroma, a stable aroma, and a rich tail, thus improving the quality of the linalool product, and the score of the product is higher than 90 points. Therefore, the linalool product prepared by the present application can be used in the field of high-end daily-use fragrance perfumes such as perfumes.

[0033] The technical solution of the present application has the following advantages:

[0034] The preparation method of linalool provided by the present application can make the catalyst break through its catalytic characteristics in the hydrogenation reaction process by adding an appropriate amount of an additive containing Zn, Co, and Fe elements in the raw material dehydro-linalool, thereby controlling the hydrogenation degree of the raw material and generating a certain amount of by-products dihydro-linalool and cyclodi-hydro-linalool that can regulate the aroma. According to tests by professional aroma testers, the linalool product prepared by the present application has a more transparent aroma, thus improving the product quality. Compared with the additional addition of a fragrance to regulate the aroma in the later stage, the process of the present application is simpler, the cost is lower, and the batch stability is better. Compared with linalool with higher purity, the linalool product prepared by the present application has a more transparent aroma, a good fragrance type, and high aroma quality.

[0035] Meanwhile, before the distillation and purification of the hydrogenation reaction liquid, the reaction liquid is washed with an alkali solution for acid removal treatment, which can inhibit the dehydration of linalool in the distillation process, thus improving the product purity and the yield of qualified products.

[0036] Additional aspects and advantages of the embodiments of the present application will be described and shown in part in the following description, or will be explained by the implementation of the embodiments of the present application. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0038] The specific experimental steps or conditions not indicated in the following examples and comparative examples can be performed according to the conventional experimental steps or conditions described in the literature in the art. The reagents or instruments used are not indicated by the manufacturer, and are all conventional reagent products that can be obtained by purchase.

[0039] In the examples and comparative examples of the present application, the reagents used are as follows:

[0040] Hydrogen (purity 99.9%), Dalian Guangming Special Gases Co., Ltd.;

[0041] Zinc phosphate, zinc acetate, iron phosphate, cobalt phosphate, iron acetate, cobalt acetate, Sinopharm Group;

[0042] Pd / CaCO3 catalyst, Jiangsu Xinnuo;

[0043] Dehydrolinalool, Haichuan Chemical.

[0044] The gas chromatography test conditions used in the present application are as follows:

[0045] Instrument model: Agilent 7890B;

[0046] Chromatographic column: DB-5 (30 m x 0.25 mm x 0.25 μm);

[0047] Column temperature: initial temperature 80℃, temperature rising to 150℃ at 10℃ / min, holding for 5 min, then temperature rising to 300℃ at 20℃ / min, holding for 10 min;

[0048] Injection port temperature: 200℃;

[0049] FID detector temperature: 300℃;

[0050] Split injection, split ratio 50:1;

[0051] Injection amount: 2.0 μm;

[0052] N2flow rate: 40 ml / min;

[0053] H2flow rate: 400 ml / min.

[0054] Example 1

[0055] The preparation method of linalool provided in the present embodiment comprises the following steps:

[0056] 1) Take 100 g of dehydro-linalool, add 0.002 g of zinc phosphate to it, mix well and reserve.

[0057] 2) Add anhydrous ethanol (50 g) and Pd / CaCO3 catalyst (2 g) to a 50 ml micro fluidized bed reactor, seal the cover, pressurize to 3 MPa with N2, check for leaks, confirm that the reactor is sealed well, replace with N2 for 3 times, then replace with H2 for 3 times, and empty the H2 in the reactor. Turn on the hydrogen, the hydrogen flow rate is 5 ml / s, make the catalyst in a fluidized state, control the oil bath heating and the reactor cooling, and maintain the reaction temperature at 60℃, the reaction pressure is 2 MPa. Then, slowly pump the Zn-containing dehydro-linalool raw material prepared in step 1) into the reactor at a feed rate of 3 mL / min, continuously feed, and continuously collect.

[0058] 3) The reaction liquid obtained in step 2) is washed with 70℃ 5wt% sodium hydroxide aqueous solution (40g) for 30min, the organic phase is collected and sent to a vacuum rectification column (the theoretical plate number is 17), the bottom temperature of the rectification column is controlled at 150℃, the top temperature is 100℃, and the internal pressure of the column is 50 Pa, to remove organic solvents, water and other impurities, and the linalool with a purity of more than 96% collected at the top is used as qualified product.

[0059] The product is detected, the linalool content is 96.8wt%, the ring dehydro-linalool content is 2.2wt%, and the dihydro-linalool content is 0.3wt%.

[0060] Example 2

[0061] Linalool is prepared according to the method of Example 1, except that the amount of zinc phosphate added in step 1) is 0.004 g.

[0062] Example 3

[0063] Linalool is prepared according to the method of Example 1, except that the amount of zinc phosphate added in step 1) is 0.005 g.

[0064] Example 4

[0065] Linalool is prepared according to the method of Example 1, except that the amount of zinc phosphate added in step 1) is 0.001 g.

[0066] Example 5

[0067] Linalool is prepared according to the method of Example 1, except that the amount of zinc acetate added in step 1) is 0.003 g.

[0068] Example 6

[0069] Linalool was prepared according to the method of Example 1, except that in step 1) the amount of iron phosphate added was 0.004 g.

[0070] Example 7

[0071] Linalool was prepared according to the method of Example 1, except that in step 1) the amount of cobalt acetate added was 0.002 g.

[0072] Example 8

[0073] Linalool was prepared according to the method of Example 1, except that in step 2) the amount of catalyst used was 1 g.

[0074] Example 9

[0075] Linalool was prepared according to the method of Example 1, except that in step 2) 3 g of Ni / Al203 catalyst was used.

[0076] Example 10

[0077] Linalool was prepared according to the method of Example 1, except that in step 2) 0.5 g of Ni / Al203 catalyst was used.

[0078] Example 11

[0079] Linalool was prepared according to the method of Example 1, except that in step 2) the reaction temperature was 40°C and the reaction pressure was 5 MPa.

[0080] Example 12

[0081] Linalool was prepared according to the method of Example 1, except that in step 2) the reaction temperature was 100°C and the reaction pressure was 3 MPa.

[0082] Example 13

[0083] Linalool was prepared according to the method of Example 1, except that in step 2) the reaction temperature was 120°C and the reaction pressure was 2 MPa.

[0084] Example 14

[0085] Linalool was prepared according to the method of Example 1, except that in step 3) the reaction liquid was washed with 50 g of 5 wt% aqueous sodium hydroxide solution.

[0086] Example 15

[0087] Linalool was prepared according to the method of Example 1, except that in step 3) the reaction liquid was washed with 30 g of 10 wt% aqueous sodium hydroxide solution.

[0088] Example 16

[0089] The linalool was produced according to the method of Example 1, except that in step 3) the bottom temperature of the rectifying column was 140°C, the top temperature was 85°C, and the pressure in the column was 10 Pa.

[0090] Example 17

[0091] The linalool was produced according to the method of Example 1, except that in step 3) the bottom temperature of the rectifying column was 160°C, the top temperature was 110°C, and the pressure in the column was 100 Pa.

[0092] Comparative Example 1

[0093] The linalool was produced according to the method of Example 1, except that in step 1) the amount of zinc phosphate added was 0.0005 g.

[0094] Comparative Example 2

[0095] The linalool was produced according to the method of Example 1, except that in step 1) the amount of zinc phosphate added was 0.01 g.

[0096] Comparative Example 3

[0097] The linalool was produced according to the method of Example 1, except that step 1) was omitted and dehydro-linalool was directly hydrogenated and refined.

[0098] Comparative Example 4

[0099] The linalool was produced according to the method of Example 1, except that the washing process with the alkaline solution in step 3) was omitted and the reaction solution produced in step 2) was directly refined.

[0100] Comparative Example 5

[0101] 1) Into a 50 ml micro fluidized bed reactor was added anhydrous ethanol (50 g), Pd / CaCO3 catalyst (2 g) and zinc phosphate (0.002 g), the reactor was sealed, N2 was used to pressurize to 3 MPa to check for leaks, and after confirming that the reactor was sealed well, N2 was used to replace 3 times and H2 was used to replace 3 times, and the H2 in the reactor was evacuated. Hydrogen was turned on, the hydrogen flow rate was 5 ml / s, the catalyst was in a fluidized state, the oil bath heating and the reactor cooling were controlled, and the reaction temperature was maintained at 60°C, and the reaction pressure was 2 MPa. Next, dehydro-linalool raw material (100 g) was slowly pumped into the reactor at a feed rate of 3 mL / min, and continuous feeding and continuous sampling were carried out.

[0102] 2) The reaction solution obtained in step 1) was washed with 5 wt% sodium hydroxide aqueous solution (40 g) at 70 °C for 30 min, and the organic phase was collected and fed into a vacuum rectification column (theoretical plate number 17) to remove organic solvents, water and other impurities, with the bottom temperature of the rectification column controlled at 150 °C, the top temperature at 100 °C, and the pressure in the column at 50 Pa (absolute pressure). The product with a linalool purity of more than 96% was collected at the top of the column as a qualified product.

[0103] Comparative Example 6

[0104] 1) A 200 g of n-hexane, 2 g of Pd / CaCO3 catalyst, and 0.002 g of zinc phosphate were added to an autoclave, which was sealed and replaced with nitrogen for 6 times. Synthetic gas containing carbon monoxide and hydrogen with a volume ratio of 1:1 was used to replace the autoclave for 6 times, the stirring paddle was turned on, the pressure of the synthetic gas was maintained at 1.0 MPa (absolute pressure), and the temperature in the reactor was maintained at 30 °C for 12 h. The stirring was stopped and the gas was vented, and the partially hydrogenated catalyst was obtained after filtration.

[0105] 2) Anhydrous ethanol (50 g) and the partially hydrogenated catalyst (2 g) obtained in step 1) were added to a 50 ml microfluidized bed reactor, the reactor was sealed, N2 was used to pressurize to 3 MPa for leak detection, and the reactor was confirmed to be leakproof. After N2 was used to replace 3 times and H2 was used to replace 3 times, the reactor was emptied of H2. Hydrogen was turned on, the hydrogen flow rate was 5 ml / s, the catalyst was in a fluidized state, the oil bath heating and the reactor cooling were controlled, and the reaction temperature was maintained at 60 °C, and the reaction pressure was 2 MPa. Then, the dehydro-linalool raw material (100 g) was slowly pumped into the reactor at a feed rate of 3 mL / min, and the product was continuously collected.

[0106] 3) The reaction solution obtained in step 2) was washed with 5 wt% sodium hydroxide aqueous solution (40 g) at 70 °C for 30 min, and the organic phase was collected and fed into a vacuum rectification column (theoretical plate number 17) to remove organic solvents, water and other impurities, with the bottom temperature of the rectification column controlled at 150 °C, the top temperature at 100 °C, and the pressure in the column at 50 Pa (absolute pressure). The product with a linalool purity of more than 96% was collected at the top of the column as a qualified product.

[0107] The linalool products obtained in Examples 1-17 and Comparative Examples 1-6 were subjected to GC detection, and the content of each component is shown in Table 1.

[0108] Table 1 Composition of linalool product

[0109]

[0110]

[0111] As can be seen from Table 1, the linalool product prepared in the present application contains linalool with a content of >96%, dihydro-linalool with a content in the range of 0.3-1.6%, and ring-dehydro-linalool with a content of ≥2%.

[0112] Compared with Example 1, the amount of adjuvant in Comparative Example 1 is too small, resulting in too high content of the over-hydrogenated product dihydro-linalool and correspondingly low content of linalool, and also too low content of the cyclization product ring-dehydro-linalool. Similar rules also appear in Comparative Examples 3 and 5.

[0113] Compared with Example 1, the amount of adjuvant in Comparative Example 2 is too large, excessively inhibiting the activity of the catalyst, resulting in low conversion rate of the raw material, correspondingly low yield of linalool, and also too low content of the over-hydrogenated product dihydro-linalool, and slightly increased content of the cyclization product ring-dehydro-linalool. In Comparative Example 4, the alkali washing step is omitted, and it is difficult to inhibit the dehydration of linalool during rectification, thus resulting in low content of linalool and large content of ring-dehydro-linalool. In Comparative Example 6, the catalyst is pre-treated for partial deactivation, so that no adjuvant is added during the hydrogenation reaction, which results in that the reaction cannot generate ring-dehydro-linalool.

[0114] The linalool products prepared in Examples 1-17 and Comparative Examples 1-6 are submitted to 4 internal perfumers and 6 external perfumers for evaluation, and the evaluation is performed from five dimensions of aroma intensity, odor complexity, aroma characteristics, aroma persistence, and sensory evaluation, and the specific evaluation criteria are as follows:

[0115] 1. Aroma intensity (full score 20 points)

[0116] Strong (18-20 points): The aroma is very rich, can quickly and strongly attract attention, and can be obviously perceived even at a long distance.

[0117] Moderate (12-17 points): The aroma intensity is moderate, neither too strong nor too weak, and can be continuously and stably perceived.

[0118] Weak (6-11 points): The aroma is relatively weak, which needs to be close to be obviously perceived, or may be difficult to perceive in some cases.

[0119] 2. Odor complexity (full score 20 points)

[0120] High complexity (18-20 points): The aroma is composed of many different odor components, each component can be obviously distinguished, and there is good balance and coordination between each other.

[0121] Moderate complexity (12-17 points): The aroma is composed of several different odor components, but not as obviously distinguished as high complexity, and has a certain sense of hierarchy.

[0122] Simple (6-11 points): The aroma is primarily composed of a single or a few odor components, lacking complexity and depth.

[0123] 3. Aroma Character (Maximum 20 points)

[0124] Distinctive and strong (18-20 points): The aroma has very unique characteristics, easily recognizable and distinguishable from other aromas, with high recognition.

[0125] General characteristics (12-17 points): The aroma has certain characteristics, but not as prominent as distinctive and strong aromas, can be recognized but may lack some uniqueness.

[0126] Not obvious (6-11 points): The aroma characteristics are not obvious, difficult to distinguish from other aromas, lack of recognition.

[0127] 4. Aroma persistence (Maximum 20 points)

[0128] Long-lasting (18-20 points): The aroma has a very long duration in the air or in the human senses, even after a period of time it can still be perceived.

[0129] Moderate persistence (12-17 points): The duration of the aroma is moderate, can be perceived within a certain time, but not as long as long-lasting.

[0130] Short duration (6-11 points): The aroma has a short duration, quickly dissipates, difficult to maintain for a long time.

[0131] 5. Sensory evaluation (Maximum 20 points)

[0132] Excellent (18-20 points): The aroma gives a very pleasant feeling, can cause strong positive emotional response, is the best in sensory experience.

[0133] Good (12-17 points): The aroma gives a good feeling to the person, can cause positive emotional response, but may not be as deep as excellent.

[0134] General (6-11 points): The aroma gives a general feeling to the person, may not cause a special emotional response, or may have some negative feelings.

[0135] Using the above criteria, the evaluator can score each dimension according to the actual performance of the aroma, and according to the score, it is classified into the corresponding grade. The total score is the sum of the scores of the five dimensions, with a maximum score of 100 points. The average score of the aroma quality after scoring is taken as the final score of the linalool product. The results are shown in Table 2.

[0136] Table 2 Aroma evaluation of linalool product

[0137]

[0138]

[0139] From Table 2, it can be seen that the product scores of Examples 1-17 are all above 90, and the product scores of multiple examples such as Example 1 are higher than 95, compared with Comparative Examples 1-6. This indicates that the method of the present application can obtain a linalool product with more transparent aroma, better fragrance type and higher aroma quality, which can be used in higher-end daily-use fragrance perfume fields such as perfumes.

[0140] Obviously, the above examples are only examples for clearly illustrating but not limiting the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing linalool, characterized by, The method comprises the following steps: S1, uniformly mixing dehydrodihydrolinalool with an additive to form a raw material mixture; The additive comprises at least one of phosphates or acetates of Zn, Co and Fe, and the mass ratio of the additive to the dehydrodihydrolinalool is 0.001%-0.005%; S2, under the action of a catalyst, the raw material mixture is reacted with hydrogen in a solvent to obtain a reaction liquid after the reaction is completed; The catalyst comprises at least one of Ni / SiO2, Ni / Al2O3 and Pd / CaCO3, and the mass ratio of the catalyst to the dehydrodihydrolinalool is 0.005-0.03:1; S3, the reaction liquid is washed with an alkali solution, organic phase is collected, and the organic phase is subjected to rectification treatment to collect overhead distillate of the rectification tower.

2. The method of preparing linalool according to claim 1, characterized in that, The mass ratio of the additive to the dehydrodihydrolinalool is 0.002%-0.004%; And / or, the additive comprises at least one of zinc phosphate, iron phosphate, ferrous phosphate, cobalt phosphate, zinc acetate, iron acetate, ferrous acetate or cobalt acetate.

3. The method of preparing linalool according to claim 1, wherein S2 is carried out in a fluidized bed reactor, comprising the following steps: The catalyst and the solvent are loaded into the fluidized bed reactor, sealed, and hydrogen is continuously introduced into the fluidized bed reactor to ensure that the catalyst is in a fluidized state; then, the raw material mixture is slowly pumped into the fluidized bed reactor for reaction, and the reaction temperature is controlled to be 40-120 DEG C, and the reaction pressure is 1-5 MPa.

4. The method of preparing linalool according to claim 3, wherein The reaction temperature is 50-100 DEG C, and the reaction pressure is 2-4 MPa; And / or, the feeding rate of the raw material mixture is 1-5 mL / min.

5. The method for preparing linalool according to claim 1 or 3, characterized by, The mass ratio of the solvent to the dehydrodihydrolinalool is 0.5-3:1; And / or, the solvent comprises at least one of pure water, aliphatic alkanes, aromatic hydrocarbons, ethers and alcohols which do not react with dehydrodihydrolinalool.

6. The method of preparing linalool according to claim 5, wherein The mass ratio of the solvent to the dehydrodihydrolinalool is 0.5-1.5:1; And / or, the solvent comprises at least one of ethanol, methanol, n-heptane or toluene.

7. The method for preparing linalool according to claim 1 or 3, characterized by, The mass ratio of the catalyst to the dehydrodihydrolinalool is 0.01-0.02:

1.

8. The method of preparing linalool according to claim 1, wherein The alkali solution is an aqueous solution of an alkali metal hydroxide, and the content of the alkali metal hydroxide in the alkali solution is 3%-10% based on the mass of the alkali solution; And / or, the alkali metal hydroxide comprises at least one of NaOH and KOH; And / or, the mass ratio of the alkali metal hydroxide to the dehydrodihydrolinalool is 0.005-0.

025.

9. The method of preparing linalool according to claim 8, wherein The mass ratio of the alkali metal hydroxide to the dehydrodihydrolinalool is 0.01-0.

02.

10. The method for preparing linalool according to claim 1 or 8, characterized in that, The alkali solution is neutralized with the reaction liquid, the reaction temperature is 50-90 DEG C, and the reaction time is 10-50 min.

11. The method of preparing linalool according to claim 10, wherein The reaction temperature is 60-80 DEG C, and the reaction time is 20-40 min.

12. The method of preparing linalool according to claim 1, wherein The bottom temperature of the rectification tower is 130-170 DEG C, the top temperature is 80-130 DEG C, the internal pressure is 10-500 Pa, and the number of theoretical plates of the rectification tower is 15-25.

13. The method of preparing linalool according to claim 12, wherein The bottom temperature of the rectification tower is 140-160 ℃, the top temperature is 85-110 ℃, the pressure in the tower is 10-100 Pa, and the number of theoretical plates is 15-20.

14. The method of preparing linalool according to claim 1, 2, 3, 4, 6, 8, 9, 11, 12 or 13, wherein The top fraction contains >96% linalool, 0.01-2% dihydrolinalool, and ≥2% cyclodihydrolinalool.

15. The method of preparing linalool according to claim 14, wherein The top fraction contains 96.1-97% linalool, 0.6-1.2% dihydrolinalool, and 2.1-2.7% cyclodihydrolinalool.

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