Method for base-catalyzed synthesis of methyl isoamyl ketone

Abstract

The invention relates to a method for synthesizing methyl isoamyl ketone through base catalysis, which is characterized in that acetone and isobutyraldehyde are used as initiators, and a composite catalyst comprising a base catalyst and a noble metal catalyst is used. Wherein the alkali catalyst is in the form of an aqueous solution of solid alkali; the mass concentration of the solid alkali in the aqueous solution is 30-50%. According to the method, the acetone and the isobutyraldehyde are used as initiators, and the composite catalyst of the base catalyst and the noble metal catalyst is used, so that mild reaction conditions, high selectivity of methyl isoamyl ketone and the service life of the composite catalyst of more than 5 years can be realized.

Description

Technical Field

[0001] The invention relates to a method for synthesizing methyl isoamyl ketone (MIAK), in particular to a method for synthesizing methyl isoamyl ketone by using an alkali catalyst, and belongs to the technical field of compound synthesis. Background Art

[0002] Methyl isoamyl ketone, also known as 5-methyl-2-hexanone, is an important organic compound that can be used as an organic solvent in the coating field, or as a raw material or intermediate for synthesizing other compounds or drugs. It can also be used as an extractant and a cleaning agent in the electronics industry.

[0003] Methyl isoamyl ketone can be synthesized by a variety of methods. The traditional industrial synthesis method includes the condensation of acetaldehyde under the action of base catalysis to form an intermediate, and then the oxidation reaction to form methyl isoamyl ketone; or the oxidation of isobutanol in the presence of a catalyst to form methyl isoamyl ketone. At present, the mainstream process uses isobutyraldehyde and acetone as raw materials, and acetone undergoes aldol polymerization with isobutyraldehyde under the induction of a catalyst, and then hydrogenates under the action of a hydrogenation catalyst to obtain methyl isoamyl ketone. The catalyst can use a composite system of multiple catalysts, or a single catalyst system with multiple catalytic functions. Organic acids or salts or esters of organic acids, such as ammonium molybdate and magnesium oxide, or cobalt oleate and zinc decanoate, or phosphoric acid resins, etc.

[0004] These composite catalysts require a two-step synthesis process, a single catalyst system with multiple catalytic functions is expensive, and the self-polymerization reaction is relatively strong, and the catalyst life is short, ammonium catalysts and organic acid salt catalysts have poor thermal stability, are easily deactivated or active components are lost during the reaction, have a short service life, and have complex post-processing methods. In addition, acid catalysts have a corrosive effect on reaction equipment, and the generated acidic waste liquid has serious environmental pollution, making post-processing more complicated.

[0005] Therefore, there is a need for a catalyst system that can synthesize methyl isoamyl ketone via a one-pot process at low cost and under mild reaction conditions. Summary of the invention

[0006] The invention provides a method for synthesizing methyl isoamyl ketone by alkali catalysis. The method adopts a composite catalyst composed of an alkali catalyst and a noble metal catalyst, takes acetone and isobutyraldehyde as starting materials, and synthesizes methyl isoamyl ketone by a one-pot method, so as to achieve the effects of mild reaction conditions, high product purity and long catalyst life.

[0007] According to one aspect of the present invention, there is provided a method for synthesizing methyl isoamyl ketone by base catalysis, comprising using acetone and isobutyraldehyde as starting materials, and using a composite catalyst comprising a base catalyst and a noble metal catalyst to carry out a synthesis reaction;

[0008] Wherein, the alkali catalyst is in the form of an aqueous solution of a solid alkali; and the mass concentration of the solid alkali in the aqueous solution is 30-50%.

[0009] According to one embodiment, the solid base is selected from one or more of alkali metal hydroxides and alkaline earth metal hydroxides.

[0010] Wherein, based on the active component of the alkali catalyst, the amount of the alkali catalyst used is 1.5-5.5% of the mass of isobutyraldehyde.

[0011] According to one embodiment, the solid base is selected from one or more of lithium hydroxide, potassium hydroxide and sodium hydroxide.

[0012] According to one embodiment, the noble metal catalyst is selected from a platinum-carbon catalyst and a palladium-carbon catalyst, and the amount of the noble metal catalyst used is 0.1 to 1.2% of the mass of isobutyraldehyde.

[0013] During the reaction process of the method, the density of the reaction mixture is maintained at 1.3 to 1.5 g / cm 3 .

[0014] According to one embodiment, the molar ratio of acetone to isobutyraldehyde is 2 to 6:1.

[0015] According to one embodiment, the base-catalyzed method for synthesizing methyl isoamyl ketone further comprises a condensation step and a hydrogenation step; and the reaction temperature of the condensation step is 45 to 75°C, and the reaction temperature of the hydrogenation step is 130 to 140°C.

[0016] According to one embodiment, the method for synthesizing methyl isoamyl ketone by base catalysis comprises adding a first portion of acetone and the composite catalyst into a reaction device, and then gradually adding the remaining portion of a mixture of acetone and isobutyraldehyde.

[0017] According to the above-mentioned base-catalyzed method for synthesizing methyl isoamyl ketone of the present invention, by using acetone and isobutyraldehyde as starting materials and using a composite catalyst of an alkali catalyst and a noble metal catalyst, by adjusting the concentration and addition amount of the alkali catalyst, mild reaction conditions, high selectivity for methyl isoamyl ketone, and a composite catalyst life of more than 5 years can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The gas chromatogram of the product mixture according to Example 1 of the present invention;

[0019] Figure 2 The gas chromatogram of the product mixture according to Example 2 of the present invention;

[0020] Figure 3 is a gas chromatogram of the product mixture according to Comparative Example 1;

[0021] Figure 4 is a gas chromatogram of the product mixture according to Comparative Example 2;

[0022] Figure 5 is a gas chromatogram of the product mixture according to Comparative Example 3;

[0023] Figure 6 is a gas chromatogram of the product mixture according to Comparative Example 4;

[0024] Figure 7 is a gas chromatogram of the product mixture according to Comparative Example 5;

[0025] Figure 8 is a gas chromatogram of the product mixture according to Comparative Example 6;

[0026] Fig. 9 is a gas chromatogram of the product mixture according to Comparative Example 7;

[0027] Fig.10 It is the gas chromatogram of the product mixed liquid according to Comparative Example 8. DETAILED DESCRIPTION

[0028] The invention provides a one-pot method for producing methyl isoamyl ketone, which comprises a condensation step, a dehydration step and a hydrogenation step, and the steps are all carried out in the one-pot method.

[0029] In the method of the present invention, the condensation step includes using acetone and isobutyraldehyde as starting materials. Since the activity of isobutyraldehyde is much higher than that of acetone, self-condensation reaction is very likely to occur. Therefore, in order to reduce the self-condensation reaction of isobutyraldehyde and reduce the probability of collision between active isobutyraldehyde molecules, the first part of acetone and the composite catalyst can be added to the reaction device first, and then the remaining part of acetone and isobutyraldehyde are gradually added to inhibit the occurrence of side reactions such as self-condensation of isobutyraldehyde.

[0030] The composite catalyst may include an alkali catalyst and a noble metal catalyst. The alkali catalyst may be a strong base, preferably a solid strong base with excellent thermal stability. For example, the alkali catalyst may be one or more of an alkali metal hydroxide and an alkaline earth metal hydroxide, preferably an alkali metal hydroxide. Preferably, the alkali catalyst is one or more selected from lithium hydroxide, potassium hydroxide and sodium hydroxide, preferably sodium hydroxide.

[0031] Existing synthesis methods believe that the base catalyst should be in the form of an aqueous solution with a relatively low concentration, and the dosage should be kept at a low level. For example, in the synthesis route of methyl isoamyl ketone, the amount of the base catalyst usually used is about 0.8% of the mass of isobutyraldehyde. At this concentration level, the aldol condensation reaction of acetone and isobutyraldehyde can be effectively induced, and the corrosion to the reaction device is relatively low. If the amount of the base catalyst is higher than this concentration level, the induction effect will be inhibited, the selectivity of the aldol condensation reaction will be reduced, and the self-polymerization reactions of acetone and isobutyraldehyde will increase, thereby reducing the yield of methyl isoamyl ketone.

[0032] The inventors surprisingly found that when the amount of the base catalyst is within a specific relatively high range, the aldol condensation reaction of acetone and isobutyraldehyde can also be improved, and the reaction rate is significantly increased, thereby greatly reducing the respective autopolymerization reactions of acetone and isobutyraldehyde. However, when the base catalyst content exceeds the specific range, the inhibitory effect on the aldol condensation reaction of acetone and isobutyraldehyde is very obvious.

[0033] Specifically, according to one embodiment of the present invention, the alkali catalyst can be in the form of an aqueous solution of a solid strong base, preferably in the form of an aqueous solution with a mass percentage of the solid base of 30 to 50%, such as 32%, 35%, 38%, 40%, 43% or 45%. In addition, based on the active ingredient of the alkali catalyst, the amount of the alkali catalyst is 1.5 to 5.5% of the mass of the isobutyraldehyde, preferably 1.8 to 2.6%, such as 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.4%, 3.8%, 4.2%, 4.5%, 5.0% or 5.2%. Here, the solid base can be a flake base or a powdered base.

[0034] According to another embodiment of the present invention, compared with the alkali catalyst in the form of an aqueous solution with a mass content of 3 to 16%, the dilute alkali solution (3 to 16%) forms a primary cell with iron ions, accelerating the corrosion of the inner wall of the reaction device, while the alkali catalyst in the form of a 30 to 50% aqueous solution has a strong passivation effect on the inner wall of the reaction device, and then the corrosion effect on the reaction device is relatively small. The inventors found that in the reaction system, not only the absolute amount of the alkali catalyst effective component should be considered, but also the addition form and addition method of the alkali catalyst need to be considered. The alkali catalysts of different addition forms and addition methods will introduce different amounts of water into the reaction system, resulting in different contents of the synthetic raw materials and the alkali catalyst effective components in the reaction system, and the amount of water added will carry out more alkali catalysts when the reaction materials are discharged, thereby causing low post-processing efficiency and alkali catalyst loss.

[0035] Therefore, in the process of the present invention, the density of the reaction mixture can be maintained at 1.3 g / cm 3 Above, preferably 1.3 to 1.5 g / cm 3, for example 1.35 g / cm 3 , 1.4g / cm 3 or 1.45g / cm 3 .

[0036] The above-mentioned noble metal catalyst can be a platinum-carbon catalyst and / or a palladium-carbon catalyst. Further, the mass percentage content of the noble metal in the noble metal catalyst can be 1.5-3.0%, preferably 1.8-2.6%, for example, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4% or 2.5%. The amount of the noble metal catalyst can be determined according to the mass of the synthetic raw material, for example, it can be 0.1-1.2% of the mass of the synthetic raw material isobutyraldehyde, for example, 0.3%, 0.5%, 0.7%, 0.9% or 1.1%. The present invention adopts a carbon-loaded noble metal catalyst containing a single noble metal element component, which not only ensures a good catalytic effect, but also has a lower production cost due to the small amount used.

[0037] The composite catalyst according to the present invention retains good stability in each reaction of the synthesis process of methyl isoamyl ketone, is easy to recycle, and has a service life of more than 5 years.

[0038] After feeding, the reaction device is closed and filled with nitrogen to maintain the pressure at a predetermined pressure value, for example, 0.5 MPa. Hydrogen is filled into the reaction device filled with nitrogen to replace the nitrogen, and the pressure is maintained at 1.0-5.0 MPa, preferably 1.5-4.0 MPa, for example, 2.0 MPa, 2.5 MPa, 3.0 MPa or 3.5 MPa.

[0039] Condensation steps

[0040] In the method of the present invention, the condensation step includes raising the temperature of the reaction device reaching a predetermined pressure value to 45 to 120° C., preferably 50 to 100° C., such as 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C. or 95° C. According to a specific embodiment, the reaction temperature of the condensation step may be 45 to 75° C. At this temperature, acetone is rearranged under the action of an alkali catalyst and undergoes an aldol condensation reaction with isobutyraldehyde, while the self-polymerization reaction of acetone and isobutyraldehyde is less. Specifically, the reaction mechanism of this step is shown in Formulas 1 to 3 below.

[0041]

[0042]

[0043] In this step, the method of the present invention uses an excess amount of acetone to promote the conversion of isobutyraldehyde, preferably to completely convert the isobutyraldehyde. Specifically, the molar ratio of acetone to isobutyraldehyde can be 2 to 6:1, such as 3:1, 4:1 or 5:1.

[0044] In the method of the present invention, isobutyraldehyde is added gradually, for example, including adding a portion (referred to as the first portion) of acetone and the composite catalyst into a reaction device, and then gradually adding the remaining portion (referred to as the second portion) of the mixture of acetone and isobutyraldehyde, preferably adding the remaining portion of the mixture of acetone and isobutyraldehyde dropwise. According to one embodiment, the mass ratio of the acetone of the first portion to the acetone of the second portion may be 1:(1-5), for example 1:1, 1:2, 1:3, or 1:4.

[0045] According to another embodiment, the composite catalyst is pre-loaded into the reaction device, and isobutyraldehyde is gradually added into the reaction device in the form of a mixture with all of the acetone.

[0046] Dehydration step

[0047] The intermediate obtained by the above condensation reaction is further treated with an alkali catalyst to increase the temperature in the reaction device to 130-140° C. to perform a dehydration reaction. The reaction mechanism is shown in Formulas 4 and 5 below.

[0048] CH 3 COCH 2 CH(O - )CH(CH 3 ) 2 +H 2 O→CH 3 COCH 2 CH(OH)CH(CH 3 ) 2 +OH - Formula 4

[0049] CH 3 COCH 2 CH(OH)CH(CH 3 ) 2 +OH - →CH 3 COCH 2 CH=C(CH 3 ) 2 +H 2 O Formula 5

[0050] The amount of the base catalyst in the reaction device is monitored, for example, the density of the reaction mixture can be monitored to be 1.3 to 1.5 g / cm 3 , because at a certain temperature and pressure, different densities of the reaction system correspond to different alkali concentrations. Alternatively, the content of the alkali catalyst in the reaction system can be determined by sampling titration. When the density of the reaction mixture drops below 1.3 g / cm 3 When the reaction is continued, fresh or recovered base catalyst is added to the reaction device.

[0051] Hydrogenation step

[0052] Under the conditions of a reaction temperature of 130 to 140° C. and a reaction pressure of 2.0 MPa, the intermediate 5-methyl-4-ene-2-hexanone generated in the above dehydration step undergoes a hydrogenation reaction under the action of a precious metal catalyst, and the reaction mechanism is shown in the following formula 6.

[0053]

[0054] When the hydrogen pressure in the reaction device remains constant, that is, when hydrogen is not consumed, it indicates that the hydrogenation step has been completed. The reaction mixture is filtered, and the filtrate is separated into oil and water, wherein the oil phase is used for the subsequent distillation step.

[0055] Specifically, the filtrate obtained by filtering the reaction mixture cannot be directly used for the distillation operation, because the filtrate contains a high concentration of alkali catalyst, and complex reactions such as acetone self-polymerization and product self-polymerization will further occur in the distillation system, which will seriously affect the product yield. Therefore, it is necessary to first perform an oil-water separation step, separate the oil and water phases and wash the oil phase with water, and use the alkali-containing filtrate in the water phase for the alkali recovery process, and the recovered alkali can be used to supplement the alkali of the reaction system.

[0056] Main side effects

[0057] The first major side reaction is that in the dehydration step, the dehydration position is different, and 5-methyl-3-ene-2-hexanone is generated. The reaction process is shown in Formula 7.

[0058] CH 3 COCH 2 CH(OH)CH(CH 3 ) 2 +OH - →CH 3 COCH=CHC(CH 3 ) 2 +H 2 O Formula 7

[0059] Since 5-methyl-3-ene-2-hexanone also generates methyl isoamyl ketone (MIAK) after hydrogenation, it has no effect on the selectivity of the target product.

[0060] Another side reaction is that the intermediate product of the self-polymerization between acetone and acetone is directly hydrogenated to obtain methyl isobutyl ketone (Methyl Isobutyl Ketone, MIBK). The reaction process is shown in Formula 8 below.

[0061]

[0062] Another side reaction is that isobutylaldehyde undergoes self-polymerization, dehydration and hydrogenation reaction with isobutylaldehyde to obtain 2,2,4-trimethylamyl aldehyde (TMAD). The reaction process is shown in Formula 9 below.

[0063]

[0064] In the method of the present invention, a base catalyst with suitable alkalinity is selected, and the addition form and method of the base catalyst are strictly controlled, so that the selectivity and yield of the target product are improved, that is, the yield of MIAK can reach more than 92%, the selectivity can reach more than 95%, and the occurrence of the above-mentioned side reactions is reduced, and the content of MIBK in the product can be 0.5-1.0%, and the content of TMAD can be 1.5-2.0%. If the content of the base catalyst in the reaction mixture is too low, the induction effect on the aldol condensation reaction of acetone and isobutyraldehyde is insufficient, resulting in a decrease in the conversion rate of isobutyraldehyde and a decrease in the selectivity of MIAK. If the amount of the base catalyst in the reaction mixture is too high, the aldol condensation reaction of acetone and isobutyraldehyde is inhibited, which also results in a decrease in the conversion rate and a corresponding decrease in the selectivity of MIAK.

[0065] The oil phase obtained by filtering and phase separation after the hydrogenation step can be subjected to a distillation step, and the distillation step can be carried out by a conventional distillation method in the art.

[0066] The purity of MIAK obtained by the above method can reach above 98%, for example 99%.

[0067] In the method of the present invention, the starting material preferably uses excess acetone to promote the complete conversion of isobutyraldehyde, and by selecting a suitable type of base catalyst, a suitable addition form and amount of the base catalyst, and controlling the density of the reaction mixture to be between 1.3 and 1.5 g / cm 3 , so that methyl isoamyl ketone can be obtained with high selectivity. Specifically, the selectivity of methyl isoamyl ketone can be above 95%, for example, 95.5%, 96%, 96.5% or 97%.

[0068] The method of the present invention has the following advantages:

[0069] The synthetic raw materials are cheap and readily available, suitable for large-scale industrial production, improving production efficiency and reducing production costs;

[0070] The reaction temperature and pressure conditions are mild. Specifically, the reaction temperature of the polymerization step can be 45 to 120° C., and the reaction pressure can be 1.0 to 5.0 MPa, which essentially improves the safety of the reaction.

[0071] One-pot reaction, simple reaction process, low cost, easy to promote;

[0072] The base catalysis efficiency is high, the conversion rate of isobutyraldehyde can reach more than 97%, and the side reactions are reduced, and the selectivity for MIAK is as high as more than 95%;

[0073] The composite catalyst including the alkali catalyst is not easy to decompose at high temperature, has good stability, is easy to handle and recycle, and has a service life of more than 5 years.

[0074] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are used to illustrate the present invention, rather than to limit the present invention.

[0075] In the following examples and comparative examples, gas chromatography analysis was performed, and the operating conditions were as follows:

[0076] Gas chromatograph: Agilent 7890B

[0077] Capillary column HP-5: 30m×0.320mm×0.25μm (column length×column inner diameter×liquid film thickness)

[0078] Detector temperature: 250°C

[0079] Gasification chamber temperature: 220℃

[0080] Carrier gas: Nitrogen

[0081] Carrier gas flow rate: 1.0mL / min

[0082] Split ratio: 80:1

[0083] Hydrogen: 30mL / min

[0084] Column temperature: Initial temperature 60°C, increase to 220°C at a rate of 5°C / min and maintain for 2 min

[0085] Injection volume: 1 μL.

[0086] The percentages used in the following examples and comparative examples are all by mass.

[0087] Example 1 (the base catalyst is a 32% sodium hydroxide aqueous solution)

[0088] The amount of the base catalyst used is 5.33% of the mass of the isobutyraldehyde.

[0089] Use a 1L laboratory hydrogenation reactor, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 12g (0.096mol) of a 32% sodium hydroxide aqueous solution, add 0.865g of a platinum-carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and maintain the pressure to 0.5MPa, wherein the acetone consists of a first part mixed with the sodium hydroxide aqueous solution and a second part mixed with the isobutyraldehyde, and the mass ratio of the first part to the second part is 1:1;

[0090] Replace nitrogen with hydrogen and add hydrogen to 2.0MPa, start stirring, raise the temperature to 70℃ to start the reaction, and control the temperature below 75℃; at this time, the density of the reaction mixture is 1.3g / cm 3 .

[0091] During the reaction, the consumed amount of hydrogen was added, and the reaction lasted for about 0.75 h until no hydrogen was absorbed, and the pressure was maintained for 30 min; the product mixture was sampled and analyzed by gas chromatography to obtain a spectrum as shown in Figure 1 As shown, acetone (RT (i.e., the time [min] shown on the horizontal axis of the figure) 3.61, peak area accounts for 24.46%), isobutyraldehyde (RT3.96, peak area accounts for 0.14%), MIAK (RT7.70, peak area accounts for 68.93%), MIBK (RT5.25, peak area accounts for 0.82%), TMAD (RT10.65, peak area accounts for 1.54%), high boiling point impurities (RT14.44, peak area accounts for 1.54%). The conversion rate of isobutyraldehyde is calculated to be 99.86%, and the selectivity of MIAK is 96.17%.

[0092] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 98.68%.

[0093] Example 2 (the base catalyst is a 45% sodium hydroxide aqueous solution)

[0094] The amount of the base catalyst used is 5.31% of the mass of the isobutyraldehyde.

[0095] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 8.5g (0.096mol) of a 45% sodium hydroxide aqueous solution, add 0.865g of a platinum-carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and maintain the pressure at 0.5MPa, wherein the acetone consists of a first part mixed with the sodium hydroxide aqueous solution and a second part mixed with the isobutyraldehyde, and the mass ratio of the first part to the second part is 1:5;

[0096] Replace nitrogen with hydrogen and add hydrogen to 2.0MPa, start stirring, raise the temperature to 70℃ to start the reaction, and control the temperature below 72℃; at this time, the density of the reaction mixture is 1.5g / cm 3 .

[0097] During the reaction, add the consumed amount of hydrogen, react for about 0.60h until no hydrogen is absorbed, and maintain the pressure for 20min;

[0098] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 2 As shown, the acetone content is 25.22%, the isobutyraldehyde content is 0.29%, the MIAK content is 69.80%, the MIBK content is 0.55%, the TMAD content is 1.20%, the high boiling point impurity content is 1.27%, the conversion rate of isobutyraldehyde is 99.71%, and the MIAK selectivity is 97.03%.

[0099] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 99.21%.

[0100] Comparative Example 1 (the base catalyst is a 20% sodium hydroxide aqueous solution)

[0101] The amount of the base catalyst used is 3.0% of the mass of the isobutyraldehyde.

[0102] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 10.8g (0.05mol) of 20% sodium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and keep the pressure at 0.5MPa;

[0103] The nitrogen was replaced by hydrogen and added to 2.0 MPa. Stirring was started and the density of the reaction mixture was 1.20 g / cm 3 , heat to 70℃ to start the reaction, and control the temperature below 75℃;

[0104] During the reaction, add the consumed amount of hydrogen, react for about 1.5 hours until no hydrogen is absorbed, and maintain the pressure for 30 minutes;

[0105] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 3 As shown, the acetone content is 40.57%, the isobutyraldehyde content is 0.18%, the MIAK content is 33.72%, the MIBK content is 7.37%, the TMAD content is 9.65%, the high boiling point impurity content is 5.80%, the conversion rate of isobutyraldehyde is 99.82%, and the MIAK selectivity is 66.24%.

[0106] The product mixture was filtered and phase separated, and the oil phase filtrate was distilled under reduced pressure to obtain MIAK with a purity of 93.46%.

[0107] Comparative Example 2 (the base catalyst is a 50% sodium hydroxide aqueous solution)

[0108] The amount of the base catalyst used is 3.0% of the mass of the isobutyraldehyde.

[0109] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 4.32g (0.05mol) of 50% sodium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and keep the pressure at 0.5MPa;

[0110] Replace nitrogen with hydrogen and add hydrogen to 2.0 MPa. Stir and the density of the reaction mixture is 1.50 g / cm 3 , heat to 45℃ to start the reaction, and control the temperature below 50℃;

[0111] During the reaction, add the consumed amount of hydrogen, react for about 1.0h until no hydrogen is absorbed, and maintain the pressure for 30min;

[0112] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 4 As shown, the acetone content is 38.35%, the isobutyraldehyde content is 0.17%, the MIAK content is 32.42%, the MIBK content is 7.34%, and the TMAD content is 14.80%; the high boiling point impurity content is 3.35%, the conversion rate of isobutyraldehyde is 99.83%, and the MIAK selectivity is 55.15%.

[0113] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 94.50%.

[0114] Comparative Example 3 (the base catalyst is a 3% sodium hydroxide aqueous solution)

[0115] The amount of the base catalyst used is 4.16% of the mass of the isobutyraldehyde.

[0116] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 100.0g (0.075mol) of 3% sodium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and keep the pressure at 0.5MPa;

[0117] The nitrogen was replaced by hydrogen and added to 2.0 MPa. Stirring was started and the density of the reaction mixture was 1.02 g / cm 3, heat to 100℃ to start the reaction, and control the temperature below 120℃;

[0118] During the reaction, add the consumed amount of hydrogen, react for about 2.0h until no hydrogen is absorbed, and maintain the pressure for 30min;

[0119] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 5 As shown, the acetone content is 28.15%, the isobutyraldehyde content is 1.89%, the MIAK content is 32.31%, the MIBK content is 5.11%, and the TMAD content is 13.88%; the high boiling point impurity content is 15.18%, the conversion rate of isobutyraldehyde is 98.11%, and the MIAK selectivity is 56.65%.

[0120] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 95.45%.

[0121] Comparative Example 4 (the base catalyst is 0.16% calcium hydroxide aqueous solution)

[0122] The amount of the base catalyst used is 4.16% of the mass of the isobutyraldehyde.

[0123] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 1875g (0.041mol) of 0.16% calcium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and keep the pressure at 0.5MPa;

[0124] Replace nitrogen with hydrogen, add to 2.0MPa, start stirring, raise the temperature to 100℃ to start the reaction, and control the temperature below 120℃;

[0125] During the reaction, add the consumed amount of hydrogen, react for about 4.0 hours until no hydrogen is absorbed, and maintain the pressure for 30 minutes;

[0126] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 6 As shown, the acetone content is 32.19%, the isobutyraldehyde content is 0.34%, the MIAK content is 28.86%, the MIBK content is 8.25%, the TMAD content is 13.24%, the high boiling point impurity content is 13.82%, the conversion rate of isobutyraldehyde is 99.66%, and the MIAK selectivity is 55.03%.

[0127] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 94.4%.

[0128] Comparative Example 5 (the base catalyst is a 3% sodium hydroxide aqueous solution)

[0129] The amount of the alkali catalyst used is 1% of the mass of the isobutyraldehyde.

[0130] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 24.0g (0.018mol) of 3% sodium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and maintain the pressure to 0.5MPa;

[0131] Replace nitrogen with hydrogen and add hydrogen to 2.0 MPa. Start stirring. The density of the reaction mixture is 1.02 g / cm 3 , heat to 100℃ to start the reaction, and control the temperature below 120℃;

[0132] During the reaction, add the consumed amount of hydrogen, react for about 4.0 hours until no hydrogen is absorbed, and maintain the pressure for 30 minutes;

[0133] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 7 As shown, the acetone content is 28.28%, the isobutyraldehyde content is 2.54%, the MIAK content is 31.33%, the MIBK content is 7.67%, and the TMAD content is 12.43%; the high boiling point impurity content is 14.50%, the conversion rate of isobutyraldehyde is 97.46%, and the MIAK selectivity is 58.59%.

[0134] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 96.82%.

[0135] Comparative Example 6 (the base catalyst is a 20% sodium hydroxide aqueous solution)

[0136] The amount of the base catalyst used is 5.55% of the mass of the isobutyraldehyde.

[0137] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 20g (0.10mol) of 20% sodium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3%), seal the reactor, replace with nitrogen and maintain the pressure to 0.5MPa;

[0138] Replace nitrogen with hydrogen and add hydrogen to 2.0 MPa. Start stirring. The density of the reaction mixture is 1.20 g / cm 3 , heat to 100℃ to start the reaction, and control the temperature below 120℃;

[0139] During the reaction, add the consumed amount of hydrogen, react for about 4.0 hours until no hydrogen is absorbed, and maintain the pressure for 30 minutes;

[0140] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Figure 8 As shown, the acetone content is 35.09%, the isobutyraldehyde content is 0.11%, the MIAK content is 31.67%, the MIBK content is 6.22%, and the TMAD content is 7.05%; the high boiling point impurity content is 17.55%, the conversion rate of isobutyraldehyde is 99.89%, and the MIAK selectivity is 71.61%.

[0141] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 96.6%.

[0142] Comparative Example 7 (the difference from Example 1 is that an acid catalyst is used)

[0143] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 500g sulfuric acid with a content of 0.2%, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and maintain the pressure to 0.5MPa;

[0144] Replace nitrogen with hydrogen and add to 2.0MPa. Start stirring. The density of the reaction liquid is 1.02g / cm 3 , heat to 100℃ to start the reaction, and control the temperature below 120℃;

[0145] During the reaction, add the consumed amount of hydrogen, react for about 4.0 hours until no hydrogen is absorbed, and maintain the pressure for 30 minutes;

[0146] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Fig. 9 As shown, the acetone content is 39.93%, the isobutyraldehyde content is 1.59%, the MIAK content is 31.78%, the MIBK content is 6.04%, and the TMAD content is 12.63%; the high boiling point impurity content is 4.79%, the conversion rate of isobutyraldehyde is 98.41%, and the MIAK selectivity is 58.55%.

[0147] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 96.5%.

[0148] Comparative Example 8 (3% aqueous solution of tetramethylammonium hydroxide as alkali)

[0149] The amount of the base catalyst used is 3.47% of the mass of the isobutyraldehyde.

[0150] Use a 1L hydrogenation test kettle, add 348.5g acetone (6.0mol), 72.1g isobutyraldehyde (1.0mol), 25g (0.027mol) of 10% tetramethylammonium hydroxide aqueous solution, add 0.865g platinum carbon catalyst (platinum content 3.0%), seal the reactor, replace with nitrogen and maintain the pressure to 0.5MPa;

[0151] Replace nitrogen with hydrogen and add to 2.0MPa. Start stirring. The density of the reaction liquid is 1.02g / cm 3 , heat to 100℃ to start the reaction, and control the temperature below 120℃;

[0152] During the reaction, add the consumed amount of hydrogen, react for about 4.0 hours until no hydrogen is absorbed, and maintain the pressure for 30 minutes;

[0153] The product mixture was sampled and analyzed by gas chromatography to obtain a spectrum such as Fig.10 As shown, the acetone content is 35.52%, the isobutyraldehyde content is 0.32%, the MIAK content is 35.07%, the MIBK content is 9.16%, and the TMAD content is 7.10%; the high boiling point impurity content is 10.53%, the conversion rate of isobutyraldehyde is 99.68%, and the MIAK selectivity is 73.50%.

[0154] The product mixture was filtered and the filtrate was distilled under reduced pressure to obtain MIAK with a purity of 96.4%.

Claims

1. A method for synthesizing methyl isoamyl ketone by base catalysis, characterized in that: The method comprises using acetone and isobutylaldehyde as starting materials and using a composite catalyst including an alkali catalyst and a noble metal catalyst to carry out a synthesis reaction; wherein the base catalyst is in the form of an aqueous solution of a solid base; and The mass concentration of the solid alkali in the aqueous solution is 30-50%.

2. The method for base-catalyzed synthesis of methyl isoamyl ketone according to claim 1, wherein the solid base is selected from one or more of alkali metal hydroxides and alkaline earth metal hydroxides.

3. The method for synthesizing methyl isoamyl ketone by base catalysis according to claim 1, wherein the amount of the base catalyst used is 1.5 to 5.5% of the mass of isobutyraldehyde, calculated on the basis of the active ingredient of the base catalyst.

4. The method for base-catalyzed synthesis of methyl isoamyl ketone according to claim 1, wherein the solid base is selected from one or more of lithium hydroxide, potassium hydroxide and sodium hydroxide.

5. The method for alkali-catalyzed synthesis of methyl isoamyl ketone according to claim 1, wherein the noble metal catalyst is selected from a platinum-carbon catalyst and a palladium-carbon catalyst, and the amount of the noble metal catalyst used is 0.1 to 1.2% of the mass of isobutyraldehyde.

6. The method for synthesizing methyl isoamyl ketone by base catalysis according to any one of claims 1 to 5, wherein during the reaction process of the method, the density of the reaction mixture is maintained at 1.3 to 1.5 g / cm 3 .

7. The method for synthesizing methyl isoamyl ketone by base catalysis according to claim 5, wherein the molar ratio of acetone to isobutyraldehyde is 2 to 6:

1.

8. The method for synthesizing methyl isoamyl ketone by base catalysis according to any one of claims 1 to 5, wherein: The reaction temperature is 45-140°C, and the reaction pressure is 1.0-5.0 MPa.

9. The method for alkali-catalyzed synthesis of methyl isoamyl ketone according to any one of claims 1 to 5, comprising adding a first portion of acetone and the composite catalyst into a reaction device, and then gradually adding the remaining portion of a mixture of acetone and isobutyraldehyde; or adding the composite catalyst into the reaction device in advance, and then adding a mixture of acetone and isobutyraldehyde.

10. The method for synthesizing methyl isoamyl ketone by base catalysis according to claim 8, wherein: The synthesis reaction comprises a condensation step and a hydrogenation step; and The reaction temperature of the condensation step is 45-75°C, and the reaction temperature of the hydrogenation step is 130-140°C.

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