Method for isosynthesizing linalool from geraniol and / or nerol

Abstract

The invention provides a geraniol / nerol composition and a method for isomerizing linalool from the geraniol / nerol composition, geraniol and / or nerol are isomerized into linalool in a continuous or semi-continuous manner in a reactor containing a catalyst, and the content of key components of citronellol and citronellal in a raw material is reduced, so that the content of linalool and the content of key components of citronellal are reduced. The content of geraniol is increased, and linalool with the content greater than 99% can be obtained. The problem that the catalyst is easy to inactivate is solved by adding a small amount of auxiliaries into the system, the service life of the catalyst is prolonged, and efficient utilization of raw materials is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for synthesizing linalool by isomerization of geraniol and / or nerol. BACKGROUND

[0002] Linalool is also known as benzoeol, linalyl alcohol. Linalool has a beautiful and pleasant floral fragrance, and plays an important role in many fragrance formulations. It can be used to blend various fragrances such as lily, clove, orange flower, etc., and is also an important raw material for synthesizing vitamins.

[0003] Geraniol and / or nerol can be obtained by hydrogenation of citral, and linalool can be obtained by isomerization of geraniol and / or nerol. This method has short reaction steps, high reaction yield, and low equipment investment.

[0004]

[0005] Patent CN1599706 discloses a semi-continuous method for isomerizing geraniol / nerol to linalool, using a tungsten oxo-peroxide solution as catalyst and a 10wt% 8-hydroxyquinoline / methanol solution as ligand. The reaction is a continuous / semi-continuous reaction rectification, and the final yield of the product is 92-93%. The catalyst can be continuously used for 30h.

[0006] Patent CN105218312 discloses a vanadium amine complex as catalyst.

[0007] Patent CN1402699 discloses a tungsten catalyst, and particularly discloses that the addition of amino alcohol has a great influence on the isomerization of geraniol to linalool. The addition of a proper amount of propylamino alcohol can improve the isomerization selectivity, and the main by-products are alcohol ether products and alcohol dehydration products. Water is not conducive to the isomerization reaction, and needs to be removed in time.

[0008] However, the existing technology has the following disadvantages:

[0009] 1. The reaction efficiency is low, and the loss of raw materials and products increases with the extension of reaction time. 2. The catalyst deactivation rate is fast, and the catalyst life needs to be improved; 3. The content of linalool dehydration products such as myrcene and limonene in linalool is high, resulting in a product purity of about 97%, and it is difficult to obtain a product with higher purity. SUMMARY

[0010] In view of the above problems in the prior art, the present application provides a method for synthesizing linalool by isomerization of geraniol and / or nerol. In the reactor containing the catalyst, geraniol and / or nerol are isomerized to linalool in a continuous or semi-continuous manner, and the content of linalool can reach 99%.

[0011] The present application finds in experiments that the ratio of geraniol and nerol in raw materials has a great influence on the selectivity of isomerization reaction and the activity of catalyst; in addition, a small amount of impurities in the raw materials, such as citronellol (3,7-dimethyl-6-octen-1-ol), rose alcohol (3,7-dimethyl-7-octen-1-ol) and citronellal, have a significant influence on the catalytic effect of the catalyst. In addition, in order to improve the service life of the catalyst, a small amount of additives can be added to the system to improve the problem of easy deactivation of the catalyst.

[0012] To achieve the above technical effects, the technical scheme adopted by the present application is:

[0013] The first aspect of the present application provides a geraniol / nerol composition, which meets the following requirements:

[0014] 1) the sum of geraniol and nerol content is > 97%, and the geraniol content is > 50%;

[0015] 2) the content of citronellol + rose alcohol is < 1%, and the content of citronellol is > the content of rose alcohol;

[0016] 3) the content of citronellal is < 0.005%;

[0017] The content refers to the mass percentage of each component in the composition;

[0018] In some specific embodiments, the composition meets: the sum of geraniol and nerol content is > 97%, for example 97.5%, 98%, 98.5%, 99%, etc., and the geraniol content is > 50%, for example 60%, 70%, 80%, etc., and the nerol content is > 0%;

[0019] In some specific embodiments, the composition meets: the content of citronellol + rose alcohol is < 1%, for example 0.8%, 0.6%, 0.3%, etc., and the content of citronellol is > the content of rose alcohol, wherein the content of rose alcohol can be 0%;

[0020] In some specific embodiments, the composition meets: the content of citronellal is < 0.005% and > 0%, for example 0.004%, 0.003%, 0.001%, etc.

[0021] The inventors have unexpectedly found that in the present application, geraniol is more likely to isomerize to linalool than neral, increasing the proportion of geraniol is beneficial to improve the conversion rate and selectivity, and shorten the reaction time, and improve the catalytic efficiency of the catalyst. Geraniol and neral are cis-trans isomers, but in the present application, the configuration of geraniol is more likely to complex with the catalyst to form linalool, and neral shows a disadvantage in forming linalool with the catalyst, mainly manifested as a decrease in reaction rate, and it is possible that the configuration needs to be flipped during isomerization to form linalool again. By limiting the contents of geraniol, neral, citronellol, rose alcohol, and citronellal in a certain range, the content of linalool in the synthesized linalool can reach 99%, and the problem of easy deactivation of the catalyst is obviously improved.

[0022] The present application also relates to a method for preparing the above-mentioned composition.

[0023] The content of geraniol in the geraniol / neral composition according to the present application is > 50%. As far as the content of geraniol is concerned, there have been reports in the prior art, and the required geraniol product can be directly purchased, or can be prepared by any method, but further regulation (such as separation and / or artificial addition) is required, and the contents of geraniol, neral, citronellol, rose alcohol, and citronellal all need to meet the requirements of the present application.

[0024] In some specific examples, the present application provides a purification scheme to obtain a qualified geraniol / neral composition by physical separation or chemical conversion.

[0025] In an embodiment of the present application, citral is hydrogenated to obtain geraniol and / or neral as a raw material, and vacuum rectification is performed to obtain the composition. The temperature of vacuum rectification is 60-150°C, preferably 80-120°C, and the pressure (absolute pressure) is 0.1-50 KPa, preferably 0.2-5 KPa. During vacuum rectification, the total residence time is controlled to be not more than 12 h, preferably not more than 8 h. The method for controlling the total residence time is preferably adjusting the reflux ratio after a certain amount of front fraction is collected in the rectification operation, and the characteristic index of the distillate is stable and the total residence time is shortened. In addition, during vacuum rectification, the total content of metal ions in the tower kettle is controlled to be less than 10 ppm, especially the contents of vanadium, cobalt, and nickel, which are preferably less than 3 ppm. Controlling the operating conditions can avoid or reduce the decomposition and isomerization of geraniol and / or neral, especially the cyclization and self-dehydration products. By reducing the contents of citronellol, rose alcohol, and citronellal, especially citronellal, in the raw material through vacuum rectification, the deactivation rate of the catalyst can be slowed down. Even a small amount of citronellal will affect the performance of the catalyst, so it is necessary to reduce its content as much as possible. It is speculated that the aldehyde group of citronellal or the acetal or hemiacetal structure formed by citronellal and alcohol hydroxyl group has a toxic effect on the catalyst. By cutting off the components with a geraniol content > 50% in rectification, the proportion of neral is reduced, and the catalytic efficiency can be improved.

[0026] In another aspect, the present application also relates to the use of the above-mentioned composition for preparing linalool by isomerization.

[0027] A method for preparing linalool, which comprises isomerizing geraniol and / or nerol in the presence of a catalyst and a ligand, using the above-mentioned composition as raw material.

[0028] In the present application, the system needs to maintain a certain active content during isomerization in order to slow down the deactivation of the catalyst. The active substance is citric acid and / or citric acid ester, such as ethyl citrate, triethyl citrate, butyl citrate, tributyl citrate, preferably citric acid;

[0029] The active substance is preferably added to the geraniol / nerol composition and then added to the reaction system. The amount of active substance added is 0.001-0.01% of the mass of the geraniol / nerol composition, preferably 0.002-0.005%.

[0030] In an embodiment of the present application, the catalyst is oxo-tungsten peroxide, which is used in the form of a solution (see CN1599706A and CN1402699A), and the ligand is an amino alcohol or an amino phenol, such as 8-hydroxyquinoline, triethanolamine, diethanolamine, monoethanolamine, tripropanolamine, dipropanolamine, 3-amino-1-propanol, 1-amino-2-propanol, 2-amino-1-propanol, butyldiethanolamine, methyldiisopropanolamine, N-(2-hydroxy-benzyl)-amine or N,N'-bis-(2-hydroxy-benzyl)-1,2-diaminoethane, etc., preferably 8-hydroxyquinoline;

[0031] Preferably, the amount of catalyst added (in terms of tungsten atom mass) is 0.05-1% of the mass of the geraniol / nerol composition, preferably 0.1-0.5%.

[0032] The molar amount of the ligand is 0.01-10 times, preferably 0.3-5 times, the amount of tungsten atoms.

[0033] In an embodiment of the present application, the isomerization reaction temperature is 90-180°C, preferably 120-160°C. In order to promote the generation of linalool, the reaction can be carried out under reduced pressure, with a reaction pressure (absolute pressure) of 1-20 KPa, preferably 5-15 KPa.

[0034] The present application has the following beneficial effects:

[0035] The present application can prepare linalool with purity of 99% by controlling the geraniol and / or nerol index, reducing or eliminating negative factors, improving reaction efficiency and prolonging catalyst life. In addition, the catalyst effect can be further enhanced by adding a small amount of active components, so that the reaction has high activity and long period operation.

[0036] The method of the present application is simple and easy to operate, can improve the yield of linalool, and has practicality and operability. DETAILED DESCRIPTION

[0037] The following examples will further illustrate the method provided by the present application, but the present application is not limited to the listed examples, and any other known changes within the scope of the claims of the present application should also be included.

[0038] The main raw material source information in the examples and comparative examples of the present application is as follows, and other materials not specifically mentioned are obtained from ordinary commercial channels:

[0039] Geraniol-wan01 specification: geraniol content 99.52%, nerol content 0.19%, citronellol content 0.06%, rose alcohol content 0.01%, citronellal content 0.001%, and the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.;

[0040] Geraniol-wan02 specification: geraniol content 61.52%, nerol content 36.21%, citronellol content 1.71%, rose alcohol content 0.07%, citronellal content 0.013%, and the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.;

[0041] Geraniol-wan03 specification: geraniol content 40.77%, nerol content 55.31%, citronellol content 3.15%, rose alcohol content 0.29%, citronellal content 0.032%, and the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.;

[0042] Geraniol-wan04 specification: geraniol content 59.72%, nerol content 37.12%, citronellol content 0.91%, rose alcohol content 0.07%, citronellal content 0.015%, and the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.;

[0043] Geraniol-wan05 specification: geraniol content 29.73%, nerol content 67.82%, citronellol content 0.92%, rose alcohol content 0.05%, citronellal content 0.003%, and the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.;

[0044] Geraniol-wan06 specification: geraniol content 70.24%, neral content 28.32%, citronellol content 0.05%, nerolidol content 0.11%, citronellal content 0.025%, the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.

[0045] Geraniol-wan07 specification: geraniol content 97.32%, neral content 1.25%, citronellol content 0.51%, nerolidol content 0.01%, citronellal content 0.077%, the remaining components are other impurities; Wanhua Chemical Group Co., Ltd.

[0046] The main analysis methods used in the examples and comparative examples of the present application are as follows:

[0047] Gas chromatography: Agilent 7890B, chromatographic column HP-INNOWax, injection port temperature: 230℃; split ratio 30:1; carrier gas flow rate: 49.5ml / min; temperature program: 80℃ for 5min, at a rate of 5℃ / min to 150℃, hold for 5min, at a rate of 20℃ / min to 230℃, hold for 5min, detector temperature: 250℃.

[0048] Example 1

[0049] Geraniol purification:

[0050] Geraniol was purified by batch rectification, the theoretical plate number of the rectification column was 15, 50Kg of geraniol-wan01 was added to the column, the bottom temperature was 129-131℃, the top pressure (absolute pressure) was 100PaA, the reflux ratio was 5:1, and 5Kg of the front fraction was collected at the top. The reflux ratio was adjusted to 1:2, and 40Kg of the middle fraction (geraniol-wan01-purity) was collected, and then the temperature was lowered. The composition of the middle fraction was analyzed by gas chromatography (GC): geraniol content 99.61%, neral content 0.07%, citronellol content 0.01%, nerolidol content less than 5ppm, citronellal content less than 5ppm, and the remaining components were other impurities.

[0051] Example 2

[0052] Geraniol purification:

[0053] The geraniol-wan02 was refined by batch rectification, the theoretical plate number of the rectification tower was 15, 50 Kg geraniol-wan02 was added to the tower kettle, the tower bottom temperature was 135-137℃, the tower top pressure (absolute pressure) was 200 PaA, the reflux ratio was 5:1, 5 Kg front fraction was collected at the tower top. The reflux ratio was adjusted to 1:2, 40 Kg middle fraction (geraniol-wan02-purity) was collected after temperature reduction. The middle fraction composition was analyzed by gas chromatography (GC), the geraniol content was 65.33%, the nerol content was 33.51%, the citronellol content was 0.71%, the nerolidol content was 0.02%, the citronellal content was 0.002%, and the remaining components were other impurities.

[0054] Example 3

[0055] Nerol refining optimization:

[0056] The nerol was refined by batch rectification, the theoretical plate number of the rectification tower was 20, 50 Kg geraniol-wan03 was added to the tower kettle, the tower bottom temperature was 133-135℃, the tower top pressure (absolute pressure) was 200 PaA, the reflux ratio was 5:1, 15 Kg front fraction was collected at the tower top. The reflux ratio was adjusted to 1:2, 30 Kg middle fraction (geraniol-wan03-purity) was collected after temperature reduction. The middle fraction composition was analyzed by gas chromatography (GC), the geraniol content was 52.16%, the nerol content was 47.21%, the citronellol content was 0.23%, the nerolidol content was 0.01%, the citronellal content was 0.001%, and the remaining components were other impurities.

[0057] Example 4

[0058] Geraniol refining and purification:

[0059] The geraniol-wan04 was refined by batch rectification, the theoretical plate number of the rectification tower was 15, 50 Kg geraniol-wan04 was added to the tower kettle, the tower bottom temperature was 135-137℃, the tower top pressure (absolute pressure) was 200 PaA, the reflux ratio was 10:1, 10 Kg front fraction was collected at the tower top. The reflux ratio was adjusted to 1:2, 35 Kg middle fraction (geraniol-wan04-purity) was collected after temperature reduction. The middle fraction composition was analyzed by gas chromatography (GC), the geraniol content was 75.84%, the nerol content was 23.83%, the citronellol content was 15 ppm, the nerolidol content was less than 5 ppm, and the citronellal content was less than 5 ppm.

[0060] Example 5

[0061] Catalyst preparation: 1.29 g tungstic acid and 3.86 g 30% hydrogen peroxide were heated and dissolved at 40℃ for 6 h to obtain 5.15 g tungsten oxo-peroxide solution.

[0062] Operation process: first distillation column pot 800g geraniol-wan01 and 0.016g citric acid (i.e. to geraniol-wan01 added 0.002% citric acid), 2.63g 8-hydroxyquinoline dissolved in 25g methanol and 5.15g oxo tungsten peroxide solution mixed after adding distillation column pot. Reaction pressure (absolute pressure) 13KPa, remove methanol and water by distillation under reduced pressure, adjust the reflux ratio 5:1, the top temperature of 133-134℃ fraction, gas chromatography (GC) analysis linalool content 99.6%. With 100g / h rate of continuous feeding, adding citric acid content of 0.002% (i.e. to geraniol-wan01 added 0.002% citric acid) geraniol-wan01 solution, the top of continuous linalool, the rate of 90-105g / h, when the sampling rate is lower than 90g / h, the catalyst activity is significantly reduced, the need to replace the catalyst. In this scheme, the catalyst activity decreased significantly after 196h.

[0063] Example 6

[0064] Catalyst preparation: 2.58g tungstic acid and 15.44g 30% hydrogen peroxide were heated to dissolve at 50℃ for 4h, 18.02g oxo tungsten peroxide solution was obtained.

[0065] Operation process: first distillation column pot 800g geraniol-wan01-purity and 0.032g citric acid, 4.06g triethanolamine dissolved in 25g methanol and 18.02g oxo tungsten peroxide solution mixed after adding distillation column pot. Reaction pressure (absolute pressure) 15KPa, remove methanol and water by distillation under reduced pressure, adjust the reflux ratio 5:1, the top temperature of 138-139℃ fraction, gas chromatography (GC) analysis linalool content 99.5%. With 100g / h rate of continuous feeding, adding citric acid content of 0.004% geraniol-wan01-purity solution, the top of continuous linalool, the rate of 90-105g / h, when the sampling rate is lower than 90g / h, the catalyst activity is significantly reduced, the need to replace the catalyst. In this scheme, the catalyst activity decreased significantly after 182h.

[0066] Example 7

[0067] Catalyst preparation: 2.58g tungstic acid and 7.72g 30% hydrogen peroxide were heated to dissolve at 30℃ for 12h, 10.30g oxo tungsten peroxide solution was obtained.

[0068] Procedure: 800g of geraniol-wan02-purity obtained in example 2 and 0.024g of ethyl citrate were first charged into the distillation column, 6.58g of 8-hydroxyquinoline was dissolved in 60g of methanol and mixed with 10.30g of tungsten oxide peroxide solution, then added into the distillation column. The reaction pressure was 10KPa (absolute pressure), methanol and water were removed by vacuum distillation, the reflux ratio was adjusted to 3:1, the temperature of the fraction collected at the top of the column was 128-129°C, and the content of linalool was 99.3% by gas chromatography (GC). The continuous feeding rate was 90g / h, and the geraniol-wan02-purity solution containing 0.003% of ethyl citrate was added, linalool was continuously collected at the top of the column, and the collection rate was 81-95g / h. When the collection rate was lower than 81g / h, it was determined that the activity of the catalyst had decreased significantly, and the catalyst needed to be replaced. In this scheme, the activity of the catalyst decreased significantly after 167h of operation.

[0069] Example 8

[0070] Catalyst preparation: 2.58g of tungstic acid and 19.30g of 30% hydrogen peroxide were heated and dissolved at 40°C for 6h to obtain 21.88g of tungsten oxide peroxide solution.

[0071] Procedure: 800g of geraniol-wan03-purity obtained in example 3 and 0.04g of citric acid were first charged into the distillation column, 17.36g of N-butyl diethanolamine was dissolved in 100g of methanol and mixed with 21.88g of tungsten oxide peroxide solution, then added into the distillation column. The reaction pressure was 5KPa (absolute pressure), methanol and water were removed by vacuum distillation, the reflux ratio was adjusted to 4:1, the temperature of the fraction collected at the top of the column was 122-123°C, and the content of linalool was 99.1% by gas chromatography (GC). The continuous feeding rate was 85g / h, and the geraniol-wan03-purity solution containing 0.005% of citric acid was added, linalool was continuously collected at the top of the column, and the collection rate was 76-90g / h. When the collection rate was lower than 76g / h, it was determined that the activity of the catalyst had decreased significantly, and the catalyst needed to be replaced. In this scheme, the activity of the catalyst decreased significantly after 124h of operation.

[0072] Example 9

[0073] Catalyst preparation: 5.16g of tungstic acid and 9.65g of 30% hydrogen peroxide were heated and dissolved at 40°C for 6h to obtain 14.81g of tungsten oxide peroxide solution.

[0074] Procedure: First, 800 g of geraniol-wan04-purity obtained in Example 4 and 0.024 g of citric acid were added to the pot of a rectification column, 15.78 g of 8-hydroxyquinoline was dissolved in 100 g of methanol and mixed with 14.81 g of tungsten oxide peroxide solution, and then added to the pot of the rectification column. The reaction pressure (absolute pressure) was 5 KPa, and methanol and water were removed by distillation under reduced pressure. The reflux ratio was adjusted to 2: 1, and the fraction was collected at a top temperature of 122-123 °C. Gas chromatography (GC) analysis showed that the content of linalool was 99.7%. The linalool solution containing 0.003% citric acid was continuously fed at a rate of 100 g / h, and linalool was continuously collected at the top of the column at a rate of 90-105 g / h. When the collection rate was lower than 90 g / h, it was determined that the activity of the catalyst had decreased significantly, and the catalyst needed to be replaced. In this scheme, the activity of the catalyst decreased significantly after 260 h of operation.

[0075] Comparative Example 1

[0076] Linalool was prepared according to the method in Example 8, except that the raw material was replaced with geraniol-wan05, and other operations and parameters were unchanged. The activity of the catalyst decreased significantly after 107 h of operation, and the content of linalool in the fraction collected at the top was reduced to 91.5% by gas chromatography (GC) analysis.

[0077] Comparative Example 2

[0078] Linalool was prepared according to the method in Example 8, except that the raw material was replaced with geraniol-wan06, and other operations and parameters were unchanged. The activity of the catalyst decreased significantly after 105 h of operation, and the content of linalool in the fraction collected at the top was reduced to 98.7% by gas chromatography (GC) analysis.

[0079] Comparative Example 3

[0080] Linalool was prepared according to the method in Example 8, except that the raw material was replaced with geraniol-wan07, and other operations and parameters were unchanged. The activity of the catalyst decreased significantly after 28 h of operation.

[0081] Comparative Example 4

[0082] Linalool was prepared according to the method in Example 8, except that no citric acid was added to the raw material, and other operations and parameters were unchanged. The activity of the catalyst decreased significantly after 42 h of operation.

[0083] Comparative Example 5

[0084] Linalool was prepared according to the method in Example 5, except that the raw material was added with rose alcohol to adjust the composition, and the composition of the raw material after adjustment was as follows: geraniol content 98.66%, nerol content 0.19%, citronellol content 0.06%, rose alcohol content 0.87%, citronellal content 0.001%, and the remaining components were other impurities; other operations and parameters were unchanged. The activity of the catalyst decreased significantly after 178 hours of operation, and the linalool content in the overhead fraction was reduced to 95.2% according to gas chromatography (GC) analysis.

[0085] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and supplements without departing from the method of the present application, and these improvements and supplements should also be considered within the protection scope of the present application.

Claims

1. A geraniol / nerol composition, which satisfies the following requirements: 1) the sum of the contents of geraniol and nerol is > 97%, and the content of geraniol is > 50%; 2) the content of citronellol + rose oxide is < 1%, and the content of citronellol is > the content of rose oxide; 3) the content of citronellal is < 0.005%; the contents being the mass percentages of the components in the composition. The content of nerol is > 0%, and the content of citronellal is > 0%.

3. A process for the preparation of linalool, which comprises isomerizing geraniol and / or nerol in the presence of a catalyst, using as starting material the composition according to claim 1 or 2. The catalyst is oxo-tungsten peroxide. The catalyst is added in an amount of 0.05 to 1% by mass of tungsten atoms, preferably 0.1 to 0.5%, relative to the mass of the geraniol / nerol composition.

2. The composition of claim 1, wherein, A ligand is also used, which is an amino alcohol and / or an amino phenol, selected from at least one of 8-hydroxyquinoline, triethanolamine, diethanolamine, monoethanolamine, tripropanolamine, dipropanolamine, 3-amino-1-propanol, 1-amino-2-propanol, 2-amino-1-propanol, butyldiethanolamine, methyl diisopropanolamine, N-(2-hydroxy-benzyl)-amine or N,N'-bis-(2-hydroxy-benzyl)-1,2-diaminoethane. The molar amount of the ligand is 0.01 to 10 times, preferably 0.3 to 5 times, the amount of tungsten atoms.

4. The production method according to claim 3, characterized by, The reaction system contains an active substance, which is citric acid and / or a citric acid ester, such as at least one of ethyl citrate, triethyl citrate, butyl citrate, tributyl citrate.

5. The preparation method according to claim 4, characterized in that, The active substance is added in an amount of 0.001 to 0.01%, preferably 0.002 to 0.005%, relative to the mass of the geraniol / nerol composition.

6. The preparation method according to claim 3, characterized in that, The isomerization reaction is carried out at a temperature of 90 to 180°C, preferably 120 to 160°C.

7. The production method according to claim 6, wherein ​ 8. The preparation method according to claim 3, characterized in that, ​ 9. The production method according to claim 8, characterized by, ​ 10. The method of claim 3, wherein, ​

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