Method for synchronously preparing 3-methyl-2-butanone and 3-pentanone

Abstract

The invention belongs to the technical field of organic synthesis, and provides a method for synchronously preparing 3-methyl-2-butanone and 3-pentanone, butanone, methanol, ion exchange resin and a catalyst are mixed for alcohol ketone condensation reaction, and 3-methyl-2-butanone and 3-pentanone are obtained at the same time. Methanol and butanone are used as raw materials and react under the action of ion exchange resin and an activated carbon supported metal catalyst. According to the method, directional control of the molar ratio of 3-methyl-2-butanone to 3-pentanone is realized by accurately regulating and controlling reaction conditions, and generation of other by-products in the reaction process is relatively low. Specifically, when anion exchange resin is added into reactants, alpha-H at the edge of butanone is strong in acidity and small in steric hindrance, so that 3-pentanone is a main product (selectivity is greater than or equal to 75%); when cation exchange resin is added into reactants, alpha-H in butanone is good in stability, and 3-methyl-2-butanone is a main product (selectivity is greater than or equal to 70%).

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for the simultaneous preparation of 3-methyl-2-butanone and 3-pentanone. Background Technology

[0002] 3-Pentanone, a medium-boiling ketone solvent (boiling point 102℃), is widely used in automotive coatings, printing inks, and electronic cleaning agents due to its excellent solubility in resins, coatings, and ink systems. It is also a key raw material for the synthesis of antibiotics (such as cephalosporin drug side chains) and pesticides (such as propiconazole intermediates). 3-Methyl-2-Butanone, due to its molecular structure containing an active carbonyl group and double bonds, is mainly used in the synthesis of terpene fragrances (such as citral derivatives), resin crosslinking agents, and organic synthesis intermediates (such as ester plasticizers), with stable demand in the daily chemical, adhesive, and fine chemical industries. Both are high-value-added products among C5-C6 ketone compounds, and market demand continues to grow with the upgrading of downstream industries.

[0003] Currently, the industrial synthesis of 3-pentanone mainly relies on the 3-pentanol dehydrogenation method (CN 120117976 A). This method uses 3-pentanol as a raw material to generate 3-pentanone through a dehydrogenation reaction. However, the selectivity of catalysts (such as the Cu-Zn-Al system) for 3-pentanone is low (about 70%), and the amount of by-products (such as pentanol ether, acetic acid, etc.) generated is large, resulting in high energy consumption and increased process complexity in subsequent separation. During the reaction, the catalyst is prone to deactivation due to carbon deposition or sintering, requiring frequent regeneration or replacement, which further increases production costs. Regarding the co-synthesis of 3-pentanone and 3-methyl-2-butanone, no efficient methods have been reported in the existing technology. The formation of the two ketones requires different reaction pathways (3-pentanone requires C2+C3 condensation, and 3-methyl-2-butanone requires C4+C2 condensation). Traditional catalysts (such as NaOH, Al2O3) have weak selectivity control ability for aldol condensation, resulting in serious side reactions (such as self-condensation and over-condensation) and low raw material utilization (about 50%-60%).

[0004] Therefore, how to achieve the simultaneous synthesis of 3-methyl-2-butanone and 3-pentanone has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the prior art and provide a method for the simultaneous preparation of 3-methyl-2-butanone and 3-pentanone.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for the simultaneous preparation of 3-methyl-2-butanone and 3-pentanone, comprising the following steps: Butanone, methanol, ion exchange resin and catalyst are mixed and subjected to alcohol-ketone condensation reaction to obtain 3-methyl-2-butanone and 3-pentanone. Ion exchange resins can be anion exchange resins or cation exchange resins; When the ion exchange resin is an anion exchange resin, the yield ratio of 3-pentanone to 3-methyl-2-butanone is 3~9:1; When the ion exchange resin is a cation exchange resin, the yield ratio of 3-pentanone to 3-methyl-2-butanone is 1:2~8.

[0007] Preferably, the molar ratio of methanol to butanone is 1~5:1~5.

[0008] Preferably, the anion exchange resin is one or more of Amberlyst21, Dowex SBR, Amberjet 4200C, D201 macroporous strong base type, Amberlite IRA-93 and D301 macroporous weak base type, and the cation exchange resin is one or more of Amberlyst15, Dowex 50WX8, Amberlite IR-120, D001 macroporous strong acid type, Amberlite IRC-84 and D113 macroporous weak acid type; The mass of the ion exchange resin is 3-10% of the combined mass of butanone and methanol.

[0009] Preferably, the catalyst is a Ni-Cu / AC catalyst; The mass of the catalyst is 3-15% of the combined mass of butanone, methanol, ion exchange resin, and catalyst.

[0010] Preferably, the temperature for the alcohol-ketone condensation reaction is 150~220℃.

[0011] Preferably, the pressure for the alcohol-ketone condensation reaction is 2-5 MPa.

[0012] Preferably, the alcohol-ketone condensation reaction takes 2 to 6 hours.

[0013] This invention provides a method for the simultaneous preparation of 3-methyl-2-butanone and 3-pentanone, comprising the following steps: mixing butanone, methanol, an ion exchange resin, and a catalyst, and carrying out an alcohol-ketone condensation reaction to simultaneously obtain 3-methyl-2-butanone and 3-pentanone. This invention uses methanol and butanone as raw materials, and the reaction is carried out under the action of an ion exchange resin and an activated carbon-supported metal catalyst. This method achieves directional control of the molar ratio of 3-methyl-2-butanone to 3-pentanone by precisely controlling the reaction conditions, and the formation of other byproducts during the reaction is low. Specifically, when an anion exchange resin is added to the reactants, the α-H at the edge of butanone is highly acidic and has low steric hindrance, therefore 3-pentanone is the major product (selectivity ≥75%); when a cation exchange resin is added to the reactants, the α-H inside butanone has good stability, and 3-methyl-2-butanone is the major product (selectivity ≥70%).

[0014] Compared to traditional stepwise processes, this invention simplifies the reaction process from three steps to one, reducing energy consumption by 30%–40%; the raw material conversion rate is increased from 60%–70% to 85%–90% (methanol conversion ≥90%, butanone conversion ≥85%); and the product ratio can be adjusted by adding additives to meet different market demands. This method overcomes the limitations of "path competition" in traditional copolymerization, providing a new route for the green synthesis of C5-C6 ketone compounds.

[0015] The method of this invention is simple to operate and highly selective, and is suitable for the industrial-scale precise synthesis of high-value-added pesticide intermediates. Attached Figure Description

[0016] Figure 1 This is the mass spectrum of the product from Example 1. Detailed Implementation

[0017] This invention provides a method for the simultaneous preparation of 3-methyl-2-butanone and 3-pentanone, comprising the following steps: Butanone, methanol, ion exchange resin and catalyst are mixed and subjected to alcohol-ketone condensation reaction to obtain 3-methyl-2-butanone and 3-pentanone.

[0018] In this invention, the ion exchange resin is an anion exchange resin or a cation exchange resin.

[0019] In this invention, when the ion exchange resin is an anion exchange resin, the yield ratio of 3-pentanone to 3-methyl-2-butanone is 3~9:1, preferably 4~8:1, more preferably 5~7:1, and even more preferably 5.5~6:1.

[0020] In this invention, when the ion exchange resin is a cation exchange resin, the yield ratio of 3-pentanone to 3-methyl-2-butanone is 1:2 to 8, preferably 1:3 to 7, more preferably 1:4 to 6, and even more preferably 1:4.5 to 5.

[0021] In this invention, the molar ratio of methanol to butanone is preferably 1~5:1~5, more preferably 1.5~4.5:1.5~4.5, and even more preferably 2~4:2~4.

[0022] In this invention, the anion exchange resin is one or more of Amberlyst21, Dowex SBR, Amberjet 4200C, D201 macroporous strong base type, Amberlite IRA-93 and D301 macroporous weak base type, and the cation exchange resin is one or more of Amberlyst15, Dowex 50WX8, Amberlite IR-120, D001 macroporous strong acid type, Amberlite IRC-84 and D113 macroporous weak acid type.

[0023] In this invention, the mass of the ion exchange resin is preferably 3 to 10% of the combined mass of butanone and methanol, more preferably 4 to 9%, and even more preferably 5 to 8%.

[0024] In this invention, the catalyst is a Ni-Cu / AC catalyst.

[0025] In this invention, the mass of the catalyst is preferably 3 to 15% of the total mass of butanone, methanol, ion exchange resin and catalyst, more preferably 5 to 12%, and even more preferably 8 to 10%.

[0026] In this invention, the temperature of the alcohol-ketone condensation reaction is preferably 150~220℃, more preferably 170~200℃, and even more preferably 180~190℃.

[0027] In this invention, the pressure for the alcohol-ketone condensation reaction is preferably 2-5 MPa, more preferably 3-4 MPa, and even more preferably 3.4-3.6 MPa.

[0028] In this invention, the alcohol-ketone condensation reaction time is preferably 2-6 h, more preferably 3-5 h, and even more preferably 3.5-4 h.

[0029] In this invention, the reaction route is as follows: .

[0030] This invention also provides a method for preparing a Ni-Cu / AC catalyst, comprising the following steps: The Ni-Cu / AC catalyst was obtained by impregnating a mixture of nickel formate, copper formate, activated carbon, ammonia, and water, followed by calcination.

[0031] In this invention, the concentration of ammonia is preferably 20-30%, more preferably 22-28%, and even more preferably 24-26%.

[0032] In this invention, the preferred mass ratio of nickel formate, copper formate, activated carbon, ammonia, and water is 4~6:0.5~1.5:80~120:80~120:80~120, more preferably 4.5~5.5:0.6~1.4:90~110:90~110:90~110, and even more preferably 4.8~5.2:0.8~1.2:95~105:95~105:95~105.

[0033] In this invention, the immersion temperature is preferably 25~35℃, more preferably 26~34℃, and even more preferably 28~32℃; the immersion time is preferably 1~10h, more preferably 2~8h, and even more preferably 4~6h.

[0034] In this invention, the calcination temperature is preferably 300~400℃, more preferably 320~380℃, and even more preferably 340~360℃; the calcination time is preferably 1~5h, more preferably 2~4h, and even more preferably 2.5~3h.

[0035] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] The catalysts for Examples 1 and 2 are prepared as follows: nickel formate, copper formate, and activated carbon are mixed and impregnated in ammonia and water, followed by calcination; wherein, the concentration of ammonia is 25%, and the mass ratio of nickel formate, copper formate, activated carbon, ammonia, and water is 5:1:100:100:100; the impregnation temperature is 30℃ and the time is 5h; the calcination temperature is 350℃ and the time is 3h.

[0037] Example 1

[0038] 32.042 g of methanol, 72.107 g of butanone, and 5.2 g of cation exchange resin (Amberlyst 15) were added to a cleaned high-pressure reactor, followed by 5.76 g of catalyst. The high-pressure reactor was then sealed, and the sampling valve and purging valve were tightened. The temperature of the high-pressure reactor was adjusted to 200 °C, and the alcohol-ketone condensation reaction was carried out for 4 hours at a reaction pressure of 3.0 MPa. After the reaction, the reactor was cooled to room temperature, and the sample was taken, filtered, and fed into a GC-MC reactor. The conversion rate was 90% based on butanone, the selectivity for 3-methyl-2-butanone was 83%, the selectivity for 3-pentanone was 13%, and the impurities accounted for 3%.

[0039] The mass spectrometry of the product is as follows: Figure 1 As shown, this indicates that 3-methyl-2-butanone and 3-pentanone were successfully synthesized.

[0040] Example 2

[0041] 32.042 g of methanol, 72.107 g of butanone, and 5.2 g of anion exchange resin (Amberlyst21) were added to a cleaned high-pressure reactor, followed by 5.76 g of catalyst. The high-pressure reactor was then sealed, and the sampling valve and purging valve were tightened. The temperature of the high-pressure reactor was adjusted to 190 °C, and the alcohol-ketone condensation reaction was carried out at a reaction pressure of 3.0 MPa for 5 h. After the reaction, the reactor was cooled to room temperature, and the sample was taken, filtered, and fed into a GC-MC reactor. The conversion rate of butanone was 93%, the selectivity of 3-pentanone was 86%, the selectivity of 3-methyl-2-butanone was 12%, and the impurity content was 1%.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone, characterized in that, Includes the following steps: Butanone, methanol, ion exchange resin and catalyst are mixed and subjected to alcohol-ketone condensation reaction to obtain 3-methyl-2-butanone and 3-pentanone. Ion exchange resins can be anion exchange resins or cation exchange resins; When the ion exchange resin is an anion exchange resin, the yield ratio of 3-pentanone to 3-methyl-2-butanone is 3~9:1; When the ion exchange resin is a cation exchange resin, the yield ratio of 3-pentanone to 3-methyl-2-butanone is 1:2~8.

2. The method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone as described in claim 1, characterized in that, The molar ratio of methanol to butanone is 1~5:1~5.

3. The method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone as described in claim 2, characterized in that, The anion exchange resin is one or more of Amberlyst21, Dowex SBR, Amberjet 4200C, D201 macroporous strong base type, Amberlite IRA-93 and D301 macroporous weak base type, and the cation exchange resin is one or more of Amberlyst15, Dowex 50WX8, Amberlite IR-120, D001 macroporous strong acid type, Amberlite IRC-84 and D113 macroporous weak acid type; The mass of the ion exchange resin is 3-10% of the combined mass of butanone and methanol.

4. The method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone as described in claim 3, characterized in that, The catalyst is a Ni-Cu / AC catalyst; The mass of the catalyst is 3-15% of the combined mass of butanone, methanol, ion exchange resin, and catalyst.

5. The method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone as described in claim 4, characterized in that, The temperature for alcohol-ketone condensation reaction is 150~220℃.

6. The method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone as described in claim 5, characterized in that, The pressure for alcohol-ketone condensation reaction is 2-5 MPa.

7. The method for simultaneously preparing 3-methyl-2-butanone and 3-pentanone as described in claim 6, characterized in that, The alcohol-ketone condensation reaction takes 2-6 hours.

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