A method for the synthesis of unsaturated ketones

Abstract

The application discloses a synthesis method of unsaturated ketone, comprising the following steps: reacting alkoxy olefin and propargyl alcohol in a tubular reactor in the presence of an acidic solid catalyst to generate unsaturated ketone; the tubular reactor comprises N reaction tube sections connected in series, and the reactant material flows through the first reaction tube section to the Nth reaction tube section in sequence; each reaction tube section is independently provided with an acidic solid catalyst and comprises a circulation tube section for circulating part of the reactant material from a discharge port of the tube section to a feed port of the tube section; the amount of the acidic solid catalyst arranged in each reaction tube section is sequentially increased from the first reaction tube section to the Nth reaction tube section; the circulation ratio of each reaction tube section is controlled to make the reactant material in a turbulent flow state, and the circulation ratio of the first reaction tube section is 7-20; the method can realize the preparation of unsaturated ketone with high selectivity and high yield under the premise of no solvent and common acidic solid catalyst, the operation process is easy to realize, and the method is suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and more specifically to a method for synthesizing unsaturated ketones. Background Technology

[0002] In the field of fragrance and pharmaceutical synthesis, unsaturated ketones are not only important fragrances but also crucial synthetic intermediates. Examples include 6-methyl-5-hepten-2-one, geranylacetone (2,6-dimethyl-2,6-undecadien-10-one), and pseudoionone, which are essential intermediates for the synthesis of carotene, linalool, nerolidol, and ionone. Among the known patented methods for synthesizing unsaturated ketones, the Saucy-Marbet reaction method is the most promising due to its simple and readily available, inexpensive raw materials, mild reaction conditions, and ease of operation and scale-up.

[0003] In practice, the Saucy-Marbet reaction is carried out in the presence of an acidic catalyst. For example, taking the preparation of pseudoionone as an example, dehydrolinalool and 2-methoxypropylene are used as raw materials to first prepare allenones via the Saucy-Marbet reaction. Allenones then undergo isomerization under alkaline catalysis to obtain pseudoionones. The reaction formula for preparing allenones is as follows:

[0004]

[0005] The most prominent feature of this process is its rapid exothermic rate and large instantaneous heat release, which easily leads to side reactions and results in poor selectivity for the target product.

[0006] To address the aforementioned problems, existing technologies offer improved solutions. For example, patent CN111282595B discloses a method for the continuous preparation of α,γ-unsaturated diene. This process employs a fixed-bed reactor, using propargyl alcohol solution and alkoxyolefins as raw materials, and proceeds through two Saucy-Marbet reaction zones. In the first Saucy-Marbet reaction zone, a boron / phosphorus co-doped carbon nanoribbon-modified weak acid resin is used as a catalyst, while in the second Saucy-Marbet reaction zone, a sulfur / nitrogen co-doped carbon nanoribbon-modified strong acid resin is used as a catalyst. However, while this patent can control the reaction rate and thus address the issue of high instantaneous heat release in the Saucy-Marbet reaction to some extent, it not only employs multiple different catalysts with complex compositions and high preparation costs, but also requires the use of organic solvents in large quantities (the large use of organic solvents helps disperse and absorb the exothermic reaction). This places high demands on the production equipment, resulting in low overall output, long production cycles, increased production costs, and negative environmental impacts. Summary of the Invention

[0007] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide an improved method for synthesizing unsaturated ketones. This method can achieve the preparation of unsaturated ketones with high selectivity and high yield without solvents and under the premise of using common acidic solid catalysts. Moreover, the operation process is easy to implement and suitable for industrial application.

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

[0009] A method for synthesizing an unsaturated ketone, the method comprising: using alkoxyolefins and propargyl alcohols as raw materials, reacting them in a tubular reactor in the presence of an acidic solid catalyst to generate an unsaturated ketone;

[0010] The tubular reactor comprises N reaction tubes connected in series, so that the reactants flow sequentially from the first reaction tube to the Nth reaction tube, where N is an integer greater than or equal to 2.

[0011] The acidic solid catalyst is independently provided in each reaction tube section, and the amount of the acidic solid catalyst provided in each reaction tube section is controlled to increase sequentially from the first reaction tube section to the Nth reaction tube section.

[0012] Each reaction section includes a circulation section for circulating a portion of the reactants from its outlet to its inlet. The circulation ratio of each reaction section is controlled to keep the reactants in turbulent flow within each section, and the circulation ratio of the first reaction section is controlled to be 7-20.

[0013] According to some preferred aspects of the present invention, from the first reaction tube section to the Nth reaction tube section, the amount of acidic solid catalyst in the subsequent reaction tube section is controlled to be 1.5-4 times the amount of acidic solid catalyst in the preceding reaction tube section.

[0014] According to some preferred and specific aspects of the present invention, from the first reaction tube section to the Nth reaction tube section, the amount of acidic solid catalyst in the subsequent reaction tube section is controlled to be 1.5-3 times the amount of acidic solid catalyst in the preceding reaction tube section.

[0015] According to some preferred aspects of the invention, the amount of the acidic solid catalyst in the first reaction section, by mass percentage, is 0.5%-1.5% of the feed mass of propargyl alcohol during the residence time of the reactants in the first reaction section, preferably 0.5%-1.2%.

[0016] The amount of acidic solid catalyst in the Nth reaction section is 0.5%-2.5% of the feed mass of propargyl alcohol during the residence time of the reactants in the Nth reaction section, preferably 0.75%-2.0%.

[0017] According to some preferred aspects of the invention, the circulation ratios of the reaction sections other than the first reaction section are controlled to be less than the circulation ratio of the first reaction section.

[0018] According to some preferred aspects of the invention, from the first reaction section to the Nth reaction section, the circulation ratio of the subsequent reaction section is controlled to be less than the circulation ratio of the preceding reaction section.

[0019] According to some preferred and specific aspects of the invention, the circulation ratios of the reaction sections other than the first reaction section are controlled to be 1-6.

[0020] According to some preferred aspects of the invention, the residence time of the reactants in the first reaction tube section to the Nth reaction tube section is controlled to remain constant or increase.

[0021] Furthermore, from the first reaction tube section to the Nth reaction tube section, the residence time of the reactants in the subsequent reaction tube section is controlled to be 1-10 times that of the residence time of the reactants in the previous reaction tube section.

[0022] According to some preferred and specific aspects of the present invention, the residence time of the reactants in the Nth reaction tube section is controlled to be 30-240 min, and the residence time of the reactants in other reaction tube sections besides the Nth reaction tube section is greater than 1 min, preferably greater than 5 min, and more preferably greater than 10 min.

[0023] According to some preferred and specific aspects of the invention, in the tubular reactor, the reaction pressure is 0.5-1.5 MPa, preferably 0.6-1.2 MPa.

[0024] According to some preferred and specific aspects of the present invention, from the first reaction tube section to the Nth reaction tube section, the reaction temperature in the subsequent stage reaction tube section is controlled to be greater than or equal to the reaction temperature in the preceding stage reaction tube section.

[0025] In some embodiments of the present invention, the reaction temperature in the Nth reaction tube segment is controlled to be greater than the reaction temperature in any other reaction tube segment, preferably by 1.1 to 3 times, more preferably by 1.1 to 2 times;

[0026] Furthermore, when N is an integer greater than 2, the reaction temperatures of the other reaction tubes, except for the Nth reaction tube, can be the same.

[0027] In some embodiments of the present invention, when N is 2, the reaction temperature in the second-stage reaction tube is controlled to be 1.2-1.8 times the reaction temperature in the first-stage reaction tube.

[0028] In some preferred embodiments of the present invention, the reaction temperature in the first reaction tube section is 50-100°C, preferably 70-90°C;

[0029] The reaction temperature in the Nth reaction tube section is set to 100-160°C, preferably 110-130°C.

[0030] In some preferred embodiments of the present invention, the molar ratio of the alkoxyolefin to the propargyl alcohol is controlled to be 2-10:1, preferably 3-7:1.

[0031] In some embodiments of the present invention, the alkoxyolefin is one or more selected from 2-methoxypropylene, 2-ethoxypropylene, 2-propoxypropylene, and 2-isopropoxypropylene.

[0032] In some embodiments of the present invention, the propargyl alcohol is selected from one or more combinations of 2-methyl-3-butyn-2-ol, dehydrolinalool, 3-methyl-1-pentyn-3-ol, dehydroneryl alcohol, tetrahydrodehydroneryl alcohol, and dehydroisophytol.

[0033] In some preferred embodiments of the present invention, the acidic solid catalyst is one or more of the following: sulfonic acid resin, phosphoric acid resin, carboxylic acid resin, and phenolic hydroxyl resin.

[0034] In some preferred embodiments of the present invention, N is 2, 3, 4 or 5.

[0035] According to the present invention, the "circulation ratio" refers to the volumetric flow rate of the reactant circulating in the current reaction tube segment divided by the volumetric flow rate of the reactant leaving the current reaction tube segment and flowing to the next stage reaction tube segment.

[0036] According to the present invention, the "residence time of reactants in the reaction tube section" refers to the ratio of the length of the main pipe (excluding the circulation tube section) of the current reaction tube section to the flow rate of fresh material entering the current reaction tube section (i.e., the flow rate of material flowing out of the current reaction tube section and into the next stage reaction tube section); while the circulation tube section in the current reaction tube section that circulates part of the reactants to its own inlet can be set to be relatively short and have a very fast material flow rate, and its flow time is not included in the residence time of reactants in the current reaction tube section.

[0037] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0038] This invention addresses the shortcomings of existing Saucy-Marbet reaction methods for preparing unsaturated ketones, such as rapid exothermic reactions, large instantaneous heat release, and susceptibility to side reactions. It innovatively proposes a tubular reactor with multiple series-connected reaction sections for unsaturated ketone synthesis. By controlling the gradient of catalyst usage, the liquid holdup ratio in the feed and circulation sections, and especially by maintaining the reactants in a turbulent state within each reaction section and controlling the circulation in the first reaction section within a suitable range, this invention effectively mitigates the problem of rapid instantaneous heat release in the Saucy-Marbet reaction. Furthermore, the circulating material allows for faster and more uniform mixing of the reactants, improving reaction selectivity and yield. Moreover, this method can be carried out solvent-free, promoting green production. In particular, it allows the use of commonly used acidic solid catalysts, avoiding the high costs associated with complex combinations of multiple catalysts in existing technologies, making it suitable for large-scale industrial production. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of one of the tubular reactors used in the synthesis method of unsaturated ketones in this invention; wherein, 1, first reaction section; 2, acidic solid catalyst; 3, circulation section; 4, circulation pump; 5, second reaction section;

[0040] Figure 2 This is a second schematic diagram of the tubular reactor used in the synthesis method of unsaturated ketones in this invention; wherein, 1' is the first reaction section; 2' is the acidic solid catalyst; 3' is the circulation section; 4' is the circulation pump; 5' is the second reaction section; and 6' is the third reaction section.

[0041] Figure 3 The image shows the gas chromatogram of the reaction solution collected in Example 1 of this invention. The recombinant fraction is 2,8,12-trimethyl-6,7,11-tetadecarne-4-one (referred to as C16 compound), with a peak elution time of 13.035 min.

[0042] Figure 4 The mass spectrum of the recombinant C16 compound generated in Example 1 of this invention has a molecular weight of 232.2. Detailed Implementation

[0043] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0044] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0045] The following are the gas chromatography test conditions: Instrument model: Thermo Trace1300; Column: SE-30 (30m×0.32mm×0.25μm); Column temperature: initial temperature 45℃, hold for 4 min, then increase to 160℃ at 50℃ / min, hold for 24 min; Injector temperature: 280℃; Detector type: FID; Detector temperature: 280℃; Split injection, split ratio 80:1; Injection volume: 0.26μL; H2 flow rate: 30mL / min; Air flow rate: 400mL / min; Carrier gas N2 flow rate: 2mL / min.

[0046] Examples 1-9 below respectively employ Figure 1 The tubular reactor shown is used for the synthesis of unsaturated ketones, such as... Figure 1 As shown, alkoxyolefins and propargyl alcohols are fed into the first reaction section 1 at a preset feed rate (which can be conveyed by a horizontal flow pump (not shown)). After the reactants flow through the acidic solid catalyst 2, a portion of the reactants is circulated back from the outlet of the first reaction section 1 to the inlet of the first reaction section 1 via the circulation pump 4 and circulation section 3. This process not only accelerates the mixing of the materials but also makes the mixing more uniform. It also has a dilution effect, reducing the possibility of hot spots forming. The remaining reactants flow into the second reaction section 5. In the second reaction section 5, the reactants are partially circulated back to their own inlet, and the remainder is discharged, just like in the first reaction section 1. The reaction temperature, the amount of acidic solid catalyst used, the circulation ratio, and the residence time in each reaction section are controlled according to the settings.

[0047] The following Example 10 uses Figure 2 The tubular reactor shown is used for the synthesis of unsaturated ketones, such as... Figure 2As shown, alkoxyolefins and propargyl alcohols are fed into the first reaction section 1' at a preset feed rate (which can be conveyed by a horizontal flow pump (not shown)). After the reactants flow through the acidic solid catalyst 2', a portion of the reactants is circulated back from the outlet of the first reaction section 1' to the inlet of the first reaction section 1' via the circulation pump 4' and circulation section 3'. This process not only accelerates the mixing of the materials but also makes the mixing more uniform. It also has a dilution effect, reducing the possibility of hot spots forming. The remaining reactants flow into the second reaction section 5'. The reactants in the second reaction section 5' are the same as those in the first reaction section 1', with a portion circulated back to their own inlet, and the remainder enters the third reaction section 6'. The reactants in the third reaction section 6' are the same as those in the first reaction section 1', with a portion circulated back to their own inlet, and the remainder is discharged. The reaction temperature, the amount of acidic solid catalyst used, the circulation ratio, and the residence time in each reaction section are controlled according to the settings.

[0048] Example 1

[0049] This example provides a method for synthesizing an unsaturated ketone (allenone 1 in the following reaction formula), using dehydrolinalool (also known as 3,7-dimethyl-6-octen-1-yn-3-ol) and 2-methoxypropene as raw materials. The reaction formula is as follows:

[0050]

[0051] This synthesis method employs... Figure 1 The tubular reactor shown and the above-described operating procedure include: placing dehydrolinalool and 2-methoxypropylene on a weighing module, setting the feed rate of the horizontal flow pump to ensure that the feed rate of dehydrolinalool is 10.00 g / min and the feed rate of 2-methoxypropylene is 23.69 g / min, at which point the molar ratio of dehydrolinalool to 2-methoxypropylene is approximately 1:5. During the reaction, the reaction pressure is approximately 1.0 MPa. The residence time of the reactants in the first reaction section is 30 min, with a circulation ratio of 10; the residence time of the reactants in the second reaction section is 60 min, with a circulation ratio of 5. The mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction section is 6.0 g, and the mass of the solid acid catalyst resin T-63MP in the first reaction section is 3.0 g. Two tubular reactor sections were placed in temperature-controlled heating devices, with the reaction temperature of the first section at 80°C and the second section at 120°C. After the reaction, gas chromatography-mass spectrometry (GC-MS) of the reaction solution confirmed that the product was allenone 1. The GC-MS spectrum of the reaction solution is shown below. Figure 3As shown. The conversion rate of the reactant dehydrolinalool was 99.92%, and the yield of the product allenone 1 was 99.01%. The recombinant C16 compound (mass spectrum of the recombinant compound can be found in [reference]). Figure 4 The content of (as shown) is 0.82%.

[0052] Example 2

[0053] The process is basically the same as in Example 1, except that the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the first reaction tube is 3.5g, and the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction tube is 6.0g.

[0054] The conversion rate of the reactant dehydrolinalool was 99.69%, the yield of the product allenone 1 was 98.37%, and the content of the heavy component C16 compound was 0.99%.

[0055] Example 3

[0056] The process is basically the same as in Example 1, except that the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the first reaction tube section is 2.0g, and the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction tube section is 6.0g.

[0057] The conversion rate of the reactant dehydrolinalool was 99.00%, the yield of the product allenone 1 was 98.01%, and the content of the heavy component C16 compound was 0.94%.

[0058] Example 4

[0059] It is basically the same as Example 1, except that the circulation ratio of the first reaction tube is 7.

[0060] The conversion rate of the reactant dehydrolinalool was 99.51%, the yield of the product allenone 1 was 98.42%, and the content of the heavy component C16 compound was 0.98%.

[0061] Example 5

[0062] It is basically the same as Example 1, except that the circulation ratio of the first reaction tube is 15.

[0063] The conversion rate of the reactant dehydrolinalool was 99.93%, the yield of the product allenone 1 was 99.02%, and the content of the heavy component C16 compound was 0.81%.

[0064] Example 6

[0065] It is basically the same as Example 1, except that the circulation ratio of the second reaction tube is 15.

[0066] The conversion rate of the reactant dehydrolinalool was 99.90%, the yield of the product allenone 1 was 99.01%, and the content of the heavy component C16 compound was 0.83%. Although this example also achieved a good yield and a low content of heavy components, it did not achieve a significantly improved yield and heavy component content compared to Example 1, even with a significantly increased recycle ratio in the second reaction section. Therefore, the recycle ratio in the second reaction section is preferably 1-6.

[0067] Example 7

[0068] The process is basically the same as in Example 1, except that the residence time of the reactants in the first reaction tube section is 45 minutes and the residence time of the reactants in the second reaction tube section is 45 minutes.

[0069] The conversion rate of the reactant dehydrolinalool was 99.87%, the yield of the product allenone 1 was 98.68%, and the content of the heavy component C16 compound was 1.07%.

[0070] Example 8

[0071] This example provides a method for synthesizing an unsaturated ketone (allenone 2 in the reaction formula below), using 2-methyl-3-butyn-2-ol and 2-methoxypropene as raw materials. The reaction formula is as follows:

[0072]

[0073] This synthesis method employs... Figure 1The tubular reactor shown and the above-described operating procedure include: placing 2-methyl-3-butyn-2-ol and 2-methoxypropylene on a weighing module, setting the feed rate of the horizontal flow pump to ensure that the feed rate of 2-methyl-3-butyn-2-ol is 5.53 g / min and the feed rate of 2-methoxypropylene is 23.69 g / min, at which point the molar ratio of 2-methyl-3-butyn-2-ol to 2-methoxypropylene is approximately 1:5. During the reaction, the reaction pressure is approximately 1.0 MPa. The residence time of the reactants in the first reaction section is 30 min, with a circulation ratio of 10; the residence time of the reactants in the second reaction section is 60 min, with a circulation ratio of 5. The mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction section is 3.32 g, and the mass of the solid acid catalyst resin T-63MP in the first reaction section is 1.66 g. Two tubular reactors were placed in temperature-controlled heating devices, with the reaction temperature of the first reactor section at 80℃ and the reaction temperature of the second reactor section at 120℃. After the reaction, gas chromatography-mass spectrometry (GC-MS) analysis of the reaction solution confirmed that the product was allenone 2. The conversion rate of the reactant 2-methyl-3-butyn-2-ol was 99.87%, the yield of the product allenone 2 was 98.86%, and the content of the heavy component was 0.92%.

[0074] Example 9

[0075] This example provides a method for synthesizing an unsaturated ketone (allenone 3 in the reaction formula below), using dehydronerol and 2-methoxypropene as raw materials. The reaction formula is as follows:

[0076]

[0077] This synthesis method employs... Figure 1The tubular reactor shown and the above-described operating procedure include: placing dehydronerol and 2-methoxypropylene on a weighing module, setting the feed rate of the horizontal flow pump to ensure that the feed rate of dehydronerol is 14.5 g / min and the feed rate of 2-methoxypropylene is 23.69 g / min, with a feed molar ratio of approximately 1:5. During the reaction, the reaction pressure is approximately 1.0 MPa. The residence time of the reactants in the first reaction section is 30 min, with a circulation ratio of 10; the residence time of the reactants in the second reaction section is 60 min, with a circulation ratio of 5. The mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction section is 8.70 g, and the mass of the solid acid catalyst resin T-63MP in the first reaction section is 4.35 g. Two tubular reactors were placed in temperature-controlled heating devices, with the reaction temperature of the first reactor section at 80℃ and the reaction temperature of the second reactor section at 120℃. After the reaction, gas chromatography-mass spectrometry (GC-MS) analysis of the reaction solution confirmed that the product was allenone 3. The conversion rate of the reactant dehydronerol was 99.84%, the yield of the product allenone 3 was 98.83%, and the content of the heavy component was 0.93%.

[0078] Example 10

[0079] This example provides a method for synthesizing an unsaturated ketone (allenone 1 in the following reaction formula), using dehydrolinalool (also known as 3,7-dimethyl-6-octen-1-yn-3-ol) and 2-methoxypropene as raw materials. The reaction formula is as follows:

[0080]

[0081] This synthesis method employs... Figure 2 The tubular reactor shown and the above-described operating procedure include: placing dehydrolinalool and 2-methoxypropylene on a weighing module, setting the feed rate of the horizontal flow pump to ensure that the feed rate of dehydrolinalool is 10.00 g / min and the feed rate of 2-methoxypropylene is 23.69 g / min, at which point the molar ratio of dehydrolinalool to 2-methoxypropylene is approximately 1:5. During the reaction, the reaction pressure is approximately 1.0 MPa. The residence time of the reactants in the first reaction section is 15 min, with a circulation ratio of 10; the residence time of the reactants in the second reaction section is 15 min, with a circulation ratio of 5; and the residence time of the reactants in the third reaction section is 60 min, with a circulation ratio of 4.

[0082] The mass of solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the third reaction section was 6.0 g, the mass of solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction section was 3.0 g, and the mass of solid acid catalyst resin T-63MP in the first reaction section was 1.5 g. The three tubular reactors were placed in temperature-controlled heating devices, with the reaction temperature in the first reaction section at 80℃, the reaction temperature in the second reaction section at 80℃, and the reaction temperature in the third reaction section at 120℃. After the reaction, gas chromatography-mass spectrometry (GC-MS) analysis of the reaction solution confirmed that the product was allenone 1. The conversion rate of the reactant dehydrolinalool was 99.86%, the yield of the product allenone 1 was 98.92%, and the content of the heavy component C16 compound was 0.85%.

[0083] Comparative Example 1

[0084] The process is essentially the same as in Example 1, except that the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the first reaction tube is 4.5g, and the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction tube is also 4.5g. (The same amount of catalyst was added as in Example 1.)

[0085] The conversion rate of the reactant dehydrolinalool was 99.76%, the yield of the product allenone 1 was 97.75%, and the content of the heavy component C16 compound was 1.85%.

[0086] Comparative Example 2

[0087] The process is essentially the same as in Example 1, except that the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the first reaction tube is 6g, and the mass of the solid acid catalyst resin T-63MP (Kehaisi (Beijing) Technology Co., Ltd.) in the second reaction tube is 3g. (The same amount of catalyst was added as in Example 1.)

[0088] The conversion rate of the reactant dehydrolinalool was 99.82%, the yield of the product allenone 1 was 97.34%, and the content of the heavy component C16 compound was 2.28%.

[0089] Comparative Example 3

[0090] It is basically the same as Example 1, except that the circulation ratio of the first reaction tube is 5.

[0091] The conversion rate of the reactant dehydrolinalool was 98.54%, the yield of the product allenone 1 was 96.28%, and the content of the heavy component C16 compound was 1.87%.

[0092] Comparative Example 4

[0093] It is basically the same as Example 1, except that the circulation ratio of the first reaction tube is 2.

[0094] The conversion rate of the reactant dehydrolinalool was 98.49%, the yield of the product allenone 1 was 95.37%, and the content of the heavy component C16 compound was 2.31%.

[0095] Comparative Example 5

[0096] It is basically the same as Example 1, except that the circulation ratio of the second reaction tube is 0, that is, the second reaction tube does not circulate.

[0097] The conversion rate of the reactant dehydrolinalool was 95.80%, the yield of the product allenone 1 was 93.09%, and the content of the heavy component C16 compound was 1.94%.

[0098] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0099] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for synthesizing an unsaturated ketone, characterized in that, The synthesis method includes: using alkoxyolefins and propargyl alcohols as raw materials, reacting them in a tubular reactor in the presence of an acidic solid catalyst to generate unsaturated ketones; The tubular reactor comprises N reaction tubes connected in series, so that the reactants flow sequentially from the first reaction tube to the Nth reaction tube, where N is an integer greater than or equal to 2. The acidic solid catalyst is independently provided in each reaction tube section, and the amount of the acidic solid catalyst provided in each reaction tube section is controlled to increase sequentially from the first reaction tube section to the Nth reaction tube section. Each reaction section includes a circulation section for circulating a portion of the reactants from its outlet to its inlet. The circulation ratio of each reaction section is controlled to keep the reactants in turbulent flow within each section, and the circulation ratio of the first reaction section is controlled to be 7-20.

2. The method for synthesizing unsaturated ketones according to claim 1, characterized in that, From the first reaction tube section to the Nth reaction tube section, the amount of acidic solid catalyst in the subsequent reaction tube section is controlled to be 1.5-4 times the amount of acidic solid catalyst in the previous reaction tube section.

3. The method of synthesis of unsaturated ketones according to claim 1 or 2, characterized in that, The amount of acidic solid catalyst in the first reaction tube section, by mass percentage, is 0.5%-1.5% of the feed mass of propargyl alcohol during the residence time of the reactants in the first reaction tube section. The amount of acidic solid catalyst in the Nth reaction section is 0.5%-2.5% of the feed mass of propargyl alcohol during the residence time of the reactants in the Nth reaction section, by mass percentage.

4. The method of synthesis of unsaturated ketones according to claim 3, characterized in that, The amount of acidic solid catalyst in the first reaction tube section is 0.5%-1.2% of the feed mass of propargyl alcohol during the residence time of the reactants in the first reaction tube section, by mass percentage.

5. The method of claim 3, wherein the unsaturated ketone is synthesized by the reaction of the compound of formula (II) with the compound of formula (III) in the presence of a base. The amount of acidic solid catalyst in the Nth reaction section is 0.75-2.0% of the feed mass of propargyl alcohol during the residence time of the reactants in the Nth reaction section, by mass percentage.

6. The method for synthesizing unsaturated ketones according to claim 1, characterized in that, The circulation ratios of the reaction tubes other than the first reaction tube are controlled to be less than the circulation ratio of the first reaction tube.

7. The method of claim 1, wherein the unsaturated ketone is synthesized by the reaction of a compound of formula (II) with a compound of formula (III) in the presence of a base. From the first reaction tube segment to the Nth reaction tube segment, the circulation ratio of the subsequent reaction tube segment is controlled to be less than the circulation ratio of the preceding reaction tube segment.

8. The method of synthesis of unsaturated ketones according to claim 1 or 6 or 7, characterized in that, The circulation ratios of the reaction tubes other than the first reaction tube section are controlled to be 1-6.

9. The method for synthesizing unsaturated ketones according to claim 1, characterized in that, The residence time of the reactants in the first reaction tube section to the Nth reaction tube section is kept constant or increased.

10. The method of claim 9, wherein the unsaturated ketone is synthesized by the reaction of the compound of formula (II) with the compound of formula (III) in the presence of a base. From the first reaction tube section to the Nth reaction tube section, the residence time of the reactants in the subsequent reaction tube section is controlled to be 1-10 times that of the residence time of the reactants in the previous reaction tube section, the residence time of the reactants in the Nth reaction tube section is controlled to be 30-240 min, and the residence time of the reactants in the other reaction tube sections except the Nth reaction tube section is greater than 1 min.

11. The method of synthesizing unsaturated ketones according to claim 10, wherein, The residence time of the reactants in the reaction tubes other than the Nth reaction tube is greater than 5 minutes.

12. The method of synthesizing unsaturated ketones according to claim 11, wherein, The residence time of the reactants in the reaction tubes other than the Nth reaction tube is greater than 10 minutes.

13. The method of synthesis of unsaturated ketones as claimed in claim 1 wherein, In the tubular reactor, the reaction pressure is 0.5-1.5 MPa; And / or, control the molar ratio of the alkoxyolefin to the propargyl alcohol to be 2-10:1; And / or, the alkoxyolefin is selected from one or more combinations of 2-methoxypropylene, 2-ethoxypropylene, 2-propoxypropylene, and 2-isopropoxypropylene, and the propargyl alcohol is selected from one or more combinations of 2-methyl-3-butyn-2-ol, dehydrolinalool, 3-methyl-1-pentyn-3-ol, dehydroneryl alcohol, tetrahydrodehydroneryl alcohol, and dehydroisophytol; And / or, the acidic solid catalyst is one or more of the following: sulfonic acid resin, phosphoric acid resin, carboxylic acid resin, and phenolic hydroxyl resin.

14. The method for synthesizing unsaturated ketones according to claim 1, characterized in that, In the tubular reactor, the reaction pressure is 0.6-1.2 MPa.

15. The method for synthesizing unsaturated ketones according to claim 1, characterized in that, From the first reaction tube section to the Nth reaction tube section, the reaction temperature in the subsequent reaction tube section is controlled to be greater than or equal to the reaction temperature in the previous reaction tube section; The reaction temperature in the first reaction tube section is set to 50-100℃. The reaction temperature in the Nth reaction tube section is set to 100-160℃.

16. The method for synthesizing an unsaturated ketone according to claim 15, characterized in that, The reaction temperature in the first reaction tube section is set to 70-90℃.

17. The method of synthesis of unsaturated ketones according to claim 15 or 16, characterized in that, The reaction temperature in the Nth reaction tube section is set to 110-130℃.

18. The method of synthesizing unsaturated ketones of claim 1, wherein, The molar ratio of the alkoxyolefin to the propargyl alcohol is controlled to be 3-7:

1.

19. The method of synthesizing unsaturated ketones of claim 1, wherein, N is 2, 3, 4 or 5.

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