Separation method of geraniol and nerol

Abstract

The invention relates to a method for separating geraniol and nerol, which comprises the following steps: mixing a mixed solution I containing geraniol and nerol with titanate to prepare a mixed solution II; carrying out rectification treatment on the mixed solution II to respectively prepare a pure geraniol product and a mixed solution III containing nerol and titanate; and carrying out separation treatment on the mixed solution III containing nerol and titanate to prepare a pure nerol product. According to the separation method, the mixture containing geraniol and nerol can be effectively separated, the purity of geraniol and nerol obtained through separation is higher, meanwhile, the process is simple, and industrial application is facilitated.

Description

Technical Field

[0001] This application relates to the field of chemical separation technology, and in particular to a method for separating geraniol and nerol. Background Technology

[0002] Geraniol and nerol are two important monoterpenoid compounds, both with the chemical formula C10. 10 H 18 O, are cis-trans isomers (geraniol is trans structure, nerol is cis structure).

[0003]

[0004] Geraniol and nerol

[0005] Geraniol and nerol are both important fragrance compounds. Geraniol has a distinct sweet rose scent and is a relatively heavy fragrance, while nerol combines the freshness of rose and orange blossom with citrus and lemon notes. The two have different focuses in their application in the fragrance industry.

[0006] Currently, there are various industrial production processes that can produce geraniol and nerol, but most of the synthesized products are mixtures of geraniol and nerol. Due to their highly similar molecular structures and extremely similar physical properties, traditional methods make it difficult to separate geraniol and nerol into high-purity products.

[0007] One method utilizes the selective recognition of substrates by cyclodextrins to separate geraniol and nerol. However, this requires multiple processes of inclusion compound preparation, inclusion compound separation, and vacuum distillation to obtain geraniol and nerol with high purity. This approach lacks feasibility and economic viability for large-scale production, and the highest purity of geraniol and nerol obtained is only 97.2%. Another method involves vacuum intermittent distillation and flash evaporation of a mixture of geraniol and nerol in the presence of complexing agents such as calcium chloride, potassium chloride, or sodium chloride. This method also suffers from numerous process control parameters and complex operation, and the highest purity of geraniol and nerol obtained is only 95%. Summary of the Invention

[0008] Based on this, this application provides a method for separating geraniol and nerol. This separation method can effectively separate mixtures containing geraniol and nerol, and the separated geraniol and nerol have higher purity. At the same time, the process is simple and easy to apply industrially.

[0009] The specific technical solution is as follows:

[0010] A method for separating geraniol and nerol, comprising the following steps:

[0011] Mixture I containing geraniol and nerol was mixed with titanate to prepare mixture II;

[0012] The mixture II was subjected to distillation to prepare pure geraniol and mixture III containing nerol and titanate, respectively.

[0013] The mixture III containing nerol and titanate was separated to prepare pure nerol.

[0014] In one embodiment, the titanate comprises one or more compounds having the structural features shown in formula (1):

[0015] Equation (1),

[0016] R1, R2, R3, and R4 are each independently C1 to C10 alkyl groups, and may be C4 to C6 alkyl groups.

[0017] In one embodiment, the titanate includes one or more of tetrabutyl titanate, tetrapentyl titanate, and tetrahexyl titanate.

[0018] In one embodiment, based on the mass of the mixture I containing geraniol and nerol, the mass percentage of the titanate is 1% to 50%, optionally 5% to 30%, and further optionally 10% to 20%.

[0019] In one embodiment, the distillation process includes packed distillation I.

[0020] In one embodiment, the conditions for packed column distillation I include: a theoretical plate number of 50 to 100, a vacuum degree of 1 kPa to 10 kPa, a reflux ratio of 1:10 to 10:1, and a reboiler temperature of 100°C to 250°C.

[0021] In one embodiment, the separation process includes distillation or crystallization.

[0022] In one embodiment, the separation process includes plate distillation II, the conditions of which include: 10 to 50 plates, a vacuum of 0.05 kPa to 1 kPa, a reflux ratio of 1:10 to 10:1, and a reboiler temperature of 100°C to 200°C.

[0023] In one embodiment, the mixture I containing geraniol and nerol has one or two of the following characteristics:

[0024] (1) In the mixture I containing geraniol and nerol, the mass ratio of geraniol to nerol is 1:10 to 10:1;

[0025] (2) The mixture I containing geraniol and nerol is a reaction solution obtained by catalytic hydrogenation or reduction of citral.

[0026] In one embodiment, the purity of the geraniol is ≥99.5%; and / or, the purity of the nerol is ≥99.5%.

[0027] This application utilizes the addition of titanate ester to a mixture of geraniol and nerol to alter their relative volatility. Subsequent distillation allows for the effective separation of geraniol and nerol, which have very similar boiling points, achieving high purity. This overcomes the bottleneck of traditional separation methods that cannot obtain higher purity geraniol and nerol, thus improving their quality and increasing the added value of the product. Furthermore, this separation method is efficient, economical, and suitable for industrial production, significantly contributing to improving the purity of geraniol and nerol products, reducing production costs, and facilitating their industrial application. Detailed Implementation

[0028] The method for separating geraniol and nerol according to this application will be further described in detail below with reference to specific embodiments. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0030] As used herein, the terms “and / or,” “or / and,” and “and / or” may include any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all the related listed items.

[0031] In this article, "one or more" refers to any one, two or more of the listed items.

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0034] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0035] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0036] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0037] In this application, room temperature generally refers to 4℃~30℃, and preferably 20±5℃.

[0038] In this application, "alkyl" refers to a monovalent residue formed by the loss of a hydrogen atom from a saturated hydrocarbon containing a primary (normal) carbon atom, a secondary carbon atom, a tertiary carbon atom, a quaternary carbon atom, or a combination thereof. It can be a straight-chain alkyl or a branched-chain alkyl. Phrases containing this term, such as "C1-C10 alkyl," refer to alkyl groups containing 1 to 10 carbon atoms, and each occurrence can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, or C10 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(C H3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (- CH2CH2CH(CH3)2), 2-methyl-1-butyl(-CH2CH(CH3)CH2CH3), 1-hexyl(-CH2CH2CH2CH2CH2CH3), 2-hexyl(-CH(CH3)CH2CH2CH2CH3), 3-hexyl(-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl(-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl(-CH(CH3)CH( CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3 and octyl (-(CH2)7CH3).

[0039] In some embodiments of this application, a method for separating geraniol and nerol is provided, comprising the following steps:

[0040] S1: Mix mixture I containing geraniol and nerol with titanate to prepare mixture II;

[0041] S2: The mixture II is subjected to distillation to prepare pure geraniol and mixture III containing nerol and titanate, respectively;

[0042] S3: Separate the mixture III containing nerol and titanate to prepare pure nerol.

[0043] Specifically, in step S1:

[0044] Without limitation, the mixture I containing geraniol and nerol is a reaction solution obtained by catalytic hydrogenation or reduction of citral. The catalytic hydrogenation or reduction reaction can be carried out according to conventional methods in the art.

[0045] In some embodiments, the mass ratio of geraniol to nerol in the mixture I containing geraniol and nerol is 1:10 to 10:1. Specifically, this mass ratio includes, but is not limited to: 1:1, 1:3, 1:5, 1:7, 1:10, 2:1, 5:1, 7:1, 10:1, or any range between the two mentioned above.

[0046] In some embodiments, the titanate comprises one or more compounds having the structural features shown in formula (1):

[0047] Equation (1),

[0048] R1, R2, R3, and R4 are each independently C1 to C10 alkyl groups, and can be selected as C4 to C6 alkyl groups, such as n-butyl, n-pentyl, or n-hexyl.

[0049] In some embodiments, the titanate includes one or more of tetrabutyl titanate, tetrapentyl titanate, and tetrahexyl titanate.

[0050] In some embodiments, the mass percentage of the titanate ester is 1% to 50% based on the mass of the mixture I containing geraniol and nerol. Specifically, the mass percentage of the titanate ester includes, but is not limited to: 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, or any range between the foregoing. Further, the mass percentage of the titanate ester is 5% to 30%. Even further, the mass percentage of the titanate ester is 10% to 20%.

[0051] Specifically, in step S2:

[0052] In some embodiments, the distillation process includes packed column distillation I. Understandably, packed column distillation I is carried out using a packed distillation column. Specifically, a mixture II containing geraniol, nerol, and titanate is pumped into the packed distillation column via a feed pump. Geraniol vapor is condensed from the top of the distillation column by a condenser and then enters a condenser to obtain pure geraniol. A mixture III containing nerol and titanate is collected from the bottom reboiler of the distillation column.

[0053] In some embodiments, the conditions for packed column distillation I include: 50 to 100 trays, vacuum (absolute pressure) of 1 kPa to 10 kPa, reflux ratio of 1:10 to 10:1, and reboiler temperature of 100°C to 250°C. Specifically, the number of trays includes, but is not limited to: 50, 60, 70, 80, 90, 100, or any two of the above; the vacuum degree (absolute pressure) includes, but is not limited to: 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, or any two of the above; the reflux ratio includes, but is not limited to: 1:1, 1:3, 1:5, 1:7, 1:10, 2:1, 5:1, 7:1, 10:1, or any two of the above; the reboiler temperature includes, but is not limited to: 100℃, 130℃, 150℃, 170℃, 200℃, 220℃, 250℃, or any two of the above.

[0054] In some embodiments, the purity of the prepared geraniol product is ≥99.5%.

[0055] Specifically, in step S3:

[0056] Without limitation, mixture III mainly consists of nerol and titanate, which have significantly different physicochemical properties and can be separated by conventional methods. In some embodiments, the separation process for mixture III may include distillation or crystallization.

[0057] In some embodiments, the separation process includes plate distillation II. Understandably, plate distillation II is carried out using a plate distillation column. Specifically, a mixture III containing nerol and titanate is pumped into the plate distillation column via a feed pump. Nerol vapor is condensed from the top of the column by a condenser and then enters a condenser to obtain pure nerol. The titanate is collected from the bottom of the column via a reboiler.

[0058] Furthermore, the conditions for plate distillation II include: 10 to 50 plates, vacuum (absolute pressure) of 0.05 kPa to 1 kPa, reflux ratio of 1:10 to 10:1, and reboiler temperature of 100°C to 200°C. Specifically, the number of trays includes, but is not limited to: 10, 15, 20, 25, 30, 35, 40, 45, 50, or any two of the above; the vacuum degree (absolute pressure) includes, but is not limited to: 0.05 kPa, 0.1 kPa, 0.2 kPa, 0.5 kPa, 0.7 kPa, 0.8 kPa, 1 kPa, or any two of the above; the reflux ratio includes, but is not limited to: 1:1, 1:3, 1:5, 1:7, 1:10, 2:1, 5:1, 7:1, 10:1, or any two of the above; the reboiler temperature includes, but is not limited to: 100℃, 120℃, 150℃, 180℃, 200℃, or any two of the above.

[0059] In some embodiments, the purity of the prepared nerol product is ≥99.5%.

[0060] For experimental parameters not specified in the following specific embodiments, please refer to the guidelines given in this application document first, or refer to experimental manuals or other experimental methods known in the art, or refer to the experimental conditions recommended by the manufacturer.

[0061] The raw materials and reagents involved in the following specific embodiments can be obtained commercially or prepared by those skilled in the art using known methods.

[0062] In the example, the mixed solution I containing geraniol and nerol has a mass ratio of 1:3 and is derived from Wanhua's hydrogenated citral unit. It is mainly a reaction solution obtained by conventional catalytic hydrogenation of citral and is obtained through filtration.

[0063] Example 1

[0064] This embodiment describes a method for separating geraniol and nerol, and the steps are as follows:

[0065] (1) Mixing tetrabutyl titanate with mixture I to prepare mixture II, wherein the mass percentage of tetrabutyl titanate relative to mixture I is 10%;

[0066] (2) Mixture II is pumped into the packed distillation column of the first separation unit by the feed pump. The packing of the packed distillation column is metal wire mesh corrugated packing, model CY700, with a packing height of 8 meters, a theoretical number of plates of 80, a distillation vacuum (absolute pressure) of 2 kPa, a reflux ratio of 5:1, and a column bottom temperature of 220℃. After the unit is running stably, the condenser outlet valve and the column bottom outlet valve of the distillation column are opened to carry out continuous vacuum distillation operation for 10 hours. Geraniol pure product (geraniol 99.6%, nerol 0.4%) is collected from the top of the column, with a yield of 98.5%. Mixture III containing nerol and titanate is collected from the column bottom.

[0067] (3) Mixture III is pumped into the plate distillation column of the second separation unit by the feed pump. The plate distillation column has 20 plates, a distillation vacuum (absolute pressure) of 1 kPa, a reflux ratio of 1:1, and a bottom temperature of 180°C. After the unit is running stably, the condenser outlet valve and the bottom outlet valve of the distillation column are opened to carry out continuous vacuum distillation for 8 hours. Pure nerol (geraniol 0.3%, nerol 99.7%) is collected from the top of the column, with a yield of 98.7%, and tetrabutyl titanate is collected from the bottom of the column.

[0068] Example 2

[0069] This embodiment is a method for separating geraniol and nerol. The steps are the same as in Example 1, the main difference being that the mass percentage of tetrabutyl titanate is adjusted to 20% relative to mixture I.

[0070] The purity of the prepared geraniol was 99.7% and the yield was 98.8%; the purity of the prepared nerol was 99.5% and the yield was 98.3%.

[0071] Example 3

[0072] This embodiment is a method for separating geraniol and nerol. The steps are the same as in Example 1, the main difference being that the mass percentage of tetrabutyl titanate is adjusted to 1% relative to mixture I.

[0073] The purity of the prepared geraniol was 98.1%, and the yield was 97.2%; the purity of the prepared nerol was 97.9%, and the yield was 96.5%.

[0074] Example 4

[0075] This embodiment is a method for separating geraniol and nerol. The steps are the same as in Example 1, the main difference being that the mass percentage of tetrabutyl titanate is adjusted to 50% relative to mixture I.

[0076] The purity of the prepared geraniol was 99.8%, and the yield was 99.1%; the purity of the prepared nerol was 99.65%, and the yield was 97.1%.

[0077] Example 5

[0078] This embodiment is a method for separating geraniol and nerol. The steps are the same as in Example 1, the main difference being that ethyl titanate is used to replace n-butyl titanate by the same mass.

[0079] The purity of the prepared geraniol was 98.7%, and the yield was 98.2%; the purity of the prepared nerol was 98.2%, and the yield was 96.5%.

[0080] Example 6

[0081] This embodiment is a method for separating geraniol and nerol. The steps are the same as in Example 1, the main difference being that nonyl titanate is used in place of butyl titanate by mass.

[0082] The purity of the prepared geraniol was 99.3%, and the yield was 98.8%; the purity of the prepared nerol was 98.2%, and the yield was 97.3%.

[0083] Example 7

[0084] This embodiment is a method for separating geraniol and nerol. The steps are the same as in embodiment 1. The main difference is that in step (2), the packing of the packed distillation column of the first separation unit is a metal wire mesh corrugated packing, model CY700, with a packing height of 5 meters, a theoretical number of plates of 50, a distillation vacuum degree (absolute pressure) of 10 kPa, a reflux ratio of 10:1, and a column bottom temperature of 100℃.

[0085] The prepared geraniol had a purity of 99.5% and a yield of 98.3%; the prepared nerol had a purity of 99.6% and a yield of 98.5%.

[0086] Example 8

[0087] This embodiment is a method for separating geraniol and nerol. The steps are the same as in embodiment 1. The main difference is that in step (2), the packing of the packed distillation column of the first separation unit is a metal wire mesh corrugated packing, model CY700, with a packing height of 10 meters, a theoretical number of plates of 100, a distillation vacuum degree (absolute pressure) of 1 kPa, a reflux ratio of 1:10, and a column bottom temperature of 250°C.

[0088] The prepared geraniol had a purity of 99.9% and a yield of 99.1%; the nerol had a purity of 99.7% and a yield of 98.6%.

[0089] Comparative Example 1

[0090] This comparative example is a method for separating geraniol and nerol. The steps are the same as in Example 1, the main difference being that no tetrabutyl titanate was added to the mixture I.

[0091] The purity of the prepared geraniol was 87.3%, and the yield was 73.5%; the purity of the prepared nerol was 85.8%, and the yield was 92.9%.

[0092] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for separating geraniol and nerol, characterized in that, Includes the following steps: Mixture I containing geraniol and nerol was mixed with titanate to prepare mixture II; The mixture II was subjected to distillation to prepare pure geraniol and mixture III containing nerol and titanate, respectively. The mixture III containing nerol and titanate was separated to prepare pure nerol.

2. The method for separating geraniol and nerol according to claim 1, characterized in that, The titanate comprises one or more compounds having the structural features shown in formula (1): Equation (1), R1, R2, R3, and R4 are each independently C1 to C10 alkyl groups, and may be C4 to C6 alkyl groups.

3. The method for separating geraniol and nerol according to claim 2, characterized in that, The titanate includes one or more of titanate n-butyl, titanate n-pentyl, and titanate n-hexyl.

4. The method for separating geraniol and nerol according to claim 1, characterized in that, Based on the mass of the mixture I containing geraniol and nerol, the mass percentage of the titanate is 1% to 50%, optionally 5% to 30%, and further optionally 10% to 20%.

5. The method for separating geraniol and nerol according to any one of claims 1 to 4, characterized in that, Distillation processes include packed column distillation I.

6. The method for separating geraniol and nerol according to claim 5, characterized in that, The conditions for packed column distillation I include: 50~100 theoretical plates, 1kPa~10kPa vacuum, reflux ratio of 1:10~10:1, and reboiler temperature of 100℃~250℃.

7. The method for separating geraniol and nerol according to any one of claims 1 to 4 and 6, characterized in that, Separation methods include distillation or crystallization.

8. The method for separating geraniol and nerol according to claim 7, characterized in that, The separation process includes plate distillation II, and the conditions for plate distillation II include: 10 to 50 plates, 0.05 kPa to 1 kPa vacuum, reflux ratio of 1:10 to 10:1, and reboiler temperature of 100℃ to 200℃.

9. The method for separating geraniol and nerol according to any one of claims 1 to 4, 6 and 8, characterized in that, The mixture I containing geraniol and nerol has one or two of the following characteristics: (1) In the mixture I containing geraniol and nerol, the mass ratio of geraniol to nerol is 1:10 to 10:1; (2) The mixture I containing geraniol and nerol is a reaction solution obtained by catalytic hydrogenation or reduction of citral.

10. The method for separating geraniol and nerol according to any one of claims 1 to 4, 6 and 8, characterized in that, The purity of the geraniol is ≥99.5%; and / or, The purity of the nerol is ≥99.5%.

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