Preparation method of 4-methyl-2-propyl hexenal

Abstract

The invention provides a preparation method of 4-methyl-2-propyl hexenal, and relates to the technical field of organic synthesis. The preparation method comprises the following steps: with n-valeraldehyde and 2-methyl-butyraldehyde as reaction substrates, carrying out a reaction in a catalyst and a mixed solvent to obtain 4-methyl-2-propyl hexenal; wherein the catalyst is selected from hydroxide of alkali metal and / or alkoxide of alkali metal, and the mixed solvent comprises water and an alcohol organic solvent. Under the reaction system provided by the invention, the cross condensation reaction of n-valeraldehyde and 2-methyl-butyraldehyde can be highly selectively catalyzed to prepare 4-methyl-2-propyl hexenal. The method is high in reaction raw material conversion rate, mild in reaction condition, high in product selectivity, simple in separation and simple and convenient to operate; the 4-methyl-2-propyl hexenal prepared by the method is suitable for large-scale industrial production, and is also an extension of full industrialization of preparation of high alcohols by hydroformylation of mixed C4 olefins.

Description

Technical Field

[0001] This invention relates to the technical field of organic compound synthesis, and in particular to a method for preparing 4-methyl-2-propylhexenal. Background Technology

[0002] 4-Methyl-2-propylhexenal is an important organic compound widely used in the production of chemical, pharmaceutical, fragrance, and pesticide intermediates. Its unique chemical structure gives it a crucial role in fragrance synthesis, particularly in the preparation of flavorings and certain fragrance products. Due to its excellent aroma properties and strong chemical reactivity, 4-methyl-2-propylhexenal is widely used in the fragrance industry, especially as a key component of flavorings. Furthermore, it possesses potential pharmaceutical activity and can serve as an intermediate for certain drugs. With the rapid development of the fine chemical industry, the demand for high-quality, high-purity 4-methyl-2-propylhexenal is increasing daily.

[0003] Currently, the main methods for preparing 4-methyl-2-propylhexenal are as follows: 1) Preparation via the oxidation of unsaturated alcohols, but this method suffers from harsh reaction conditions and low yield. 2) Preparation via the addition reaction or selective catalytic reaction of olefins, but this is often accompanied by poor stereoselectivity, numerous byproducts, and complex post-processing. 3) Starting from simple aldehyde compounds, this method involves multiple steps such as addition and condensation reactions, but the reaction products have poor selectivity and the mixture is difficult to separate.

[0004] Existing technologies face numerous challenges in terms of chemoselectivity, side reaction control, and stability under industrial conditions. Therefore, there is an urgent need to develop an efficient industrial preparation method, especially one that directly prepares 4-methyl-2-propylhexenal through a highly selective condensation reaction based on existing industrial raw materials n-pentanal and 2-methyl-butanal.

[0005] In industrial production, the high-value utilization of mixed C4 olefins can be achieved by preparing a mixture of n-pentanal and 2-methyl-butanal from butene via hydroformylation. This process has a mature reaction route, abundant and inexpensive raw material sources. In particular, n-pentanal and 2-methyl-butanal exhibit high reactivity and are important intermediates in organic synthesis. By using a suitable catalytic system, the direct condensation reaction of these two mixed raw materials holds promise for the highly selective preparation of 4-methyl-2-propylhexenal.

[0006] In 2001, Klaus-Diether et al. prepared 4-methyl-2-propylhexenal using n-pentanal and 2-methyl-butanal as raw materials in an aqueous solution of sodium hydroxide, but the selectivity was only 24%, resulting in a huge waste of raw materials and increased separation energy costs.

[0007] In 2010, Alfred et al. used n-pentanal and 2-methyl-butanal as raw materials and sodium hydroxide as a catalyst, and at a high temperature of 130°C, they could only obtain a mixed product of 4-methyl-2-propylhexenal and 2-propyl-2-heptenal.

[0008] In 2021, Chai et al. used n-pentanal as a raw material to prepare 2-propyl-2-heptenal product with high selectivity through self-condensation reaction. Using a single raw material can avoid the problem of poor selectivity of condensation reaction.

[0009] By analyzing the structure of the raw materials and their steric hindrance, it was found that both n-pentanal and 2-methyl-butanal contain α-H, which can act as both electrophiles and nucleophiles. In the base-catalyzed reaction system, there are cross-condensation and self-condensation reactions, and theoretically there are at least three products, which leads to the chaos of the reaction system.

[0010] Although methods for synthesizing 4-methyl-2-propylhexenal already exist, problems such as imperfect catalytic systems, poor chemical selectivity, harsh reaction conditions, difficult post-processing and separation, and waste of raw materials still exist, which limit industrial applications. Therefore, designing new catalytic systems for the synthesis of 4-methyl-2-propylhexenal is of great significance.

[0011] In view of this, the present invention is hereby proposed. Summary of the Invention

[0012] The purpose of this invention is to provide a method for preparing 4-methyl-2-propylhexenal. The preparation method of this invention solves the technical problems of poor chemical selectivity, numerous side reactions, low raw material conversion rate, harsh reaction conditions, and complex post-processing in existing methods for preparing 4-methyl-2-propylhexenal.

[0013] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing 4-methyl-2-propylhexenal, the method comprising: Using n-pentanal and 2-methyl-butanal as reaction substrates, the reaction was carried out in a catalyst and a mixed solvent to obtain 4-methyl-2-propylhexenal; The catalyst is selected from alkali metal hydroxides and / or alkali metal alkoxides, and the mixed solvent includes water and alcohol organic solvents.

[0014] Furthermore, the molar ratio of n-pentanal to 2-methyl-butanal is (1~5):1, preferably (1~1.5):1.

[0015] Furthermore, the alkali metal hydroxide is selected from any one or a combination of at least two of potassium hydroxide, sodium hydroxide, and lithium hydroxide, preferably potassium hydroxide and / or sodium hydroxide, and more preferably sodium hydroxide.

[0016] Furthermore, the alkali metal alkoxide is selected from sodium alkoxide and / or potassium alkoxide.

[0017] Furthermore, the sodium alkoxide is selected from any one or a combination of at least two of sodium methoxide, sodium ethoxide, and sodium tert-butoxide.

[0018] Furthermore, the potassium alkoxide is selected from any one or a combination of at least two of potassium methoxide, potassium ethoxide, and potassium tert-butoxide.

[0019] Furthermore, the molar ratio of the catalyst to 2-methyl-butyraldehyde is (1~5):1, preferably (1~2):1.

[0020] Furthermore, the alcohol organic solvent is a C1-C10 straight-chain or branched alkyl alcohol, more preferably a C1-C4 straight-chain or branched alkyl alcohol.

[0021] Furthermore, the alcoholic organic solvent is selected from any one or a combination of at least two of methanol, ethanol, isopropanol, and tert-butanol, preferably methanol and / or ethanol, and more preferably ethanol.

[0022] Furthermore, the molar concentration of 2-methyl-butyraldehyde in the alcoholic organic solvent is 2-5 mol / L, preferably 3-4 mol / L.

[0023] Furthermore, the volume ratio of water to alcoholic organic solvent is (1~5):1, preferably (1.5~2):1.

[0024] Furthermore, the reaction is carried out in an air atmosphere.

[0025] Furthermore, the reaction temperature is 60~150℃, preferably 80~120℃.

[0026] Furthermore, the reaction time is 1 to 12 hours, preferably 4 to 8 hours.

[0027] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing 4-methyl-2-propylhexenal. This method selects a suitable catalyst and solvent, has a high conversion rate of reaction raw materials, mild reaction conditions, high product selectivity, simple separation, and convenient operation. The 4-methyl-2-propylhexenal prepared by this method is suitable for large-scale industrial production and can be used as an industrial extension of the process of hydroformylation of mixed C4 olefins to produce higher alcohols. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 The chromatogram provided in Example 1 is a characterization of the selectivity of 4-methyl-2-propylhexenal. Detailed Implementation

[0030] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In a first aspect, the present invention provides a method for preparing 4-methyl-2-propylhexenal, the method comprising: Using n-pentanal and 2-methyl-butanal as reaction substrates, the reaction was carried out in a catalyst and a mixed solvent to obtain 4-methyl-2-propylhexenal; The catalyst is selected from alkali metal hydroxides and / or alkali metal alkoxides, and the mixed solvent includes water and alcohol organic solvents.

[0033] It should be noted that the preparation method of 4-methyl-2-propylhexenal described in this invention uses n-pentanal and 2-methyl-butanal as reactants, adds a suitable catalyst and solvent, and obtains 4-methyl-2-propylhexenal in an air atmosphere. This method has high reactant conversion rate, mild reaction conditions, high product selectivity, simple separation, and convenient operation. The 4-methyl-2-propylhexenal prepared by this method is suitable for large-scale industrial production and is also an extension of the full industrialization of hydroformylation of mixed C4 olefins to produce higher alcohols.

[0034] In particular, the selection of catalysts and solvents in this invention significantly improves the selectivity and controllability of the reaction. The presence of the aqueous phase effectively regulates the solubility, dissociation strength, and reactivity of the base, inhibiting excessive condensation, self-polymerization, and oxidation side reactions of aldehydes. The organic solvent improves the miscibility and molecular diffusion of the two aldehyde raw materials, promotes effective collisions, and enhances the tendency for cross-condensation. Alkali metal hydroxides provide a stable, strongly alkaline environment, driving the deprotonation of α-hydrogens to generate the key enol anion intermediate; while alkali metal alkoxides provide basicity, their conjugated alcohols can participate in microenvironment regulation, further optimizing the reaction pathway. The synergistic effect of these two factors allows the system to preferentially guide the target cross-condensation product under mild conditions, significantly reducing competing reactions such as self-condensation, improving the generation efficiency and purity of the target aldehyde, simplifying subsequent separation and purification steps, and combining operational safety with industrial applicability.

[0035] It should be noted that the structural formula of the 4-methyl-2-propylhexenal is shown in Formula I below:

[0036] Formula I.

[0037] It should be noted that the reaction equation for the preparation method of 4-methyl-2-propylhexenal is as follows: .

[0038] As an optional implementation, the molar ratio of n-pentanal to 2-methyl-butanal is (1~5):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, etc.

[0039] In a preferred embodiment, the molar ratio of n-pentanal to 2-methyl-butanal is (1~1.5):1.

[0040] As an optional implementation, the catalyst is selected from any one or a combination of at least two of potassium hydroxide, sodium hydroxide, and lithium hydroxide.

[0041] As an optional implementation, the catalyst is selected from sodium alkoxide and / or potassium alkoxide.

[0042] As an optional implementation, the catalyst is selected from any one or a combination of at least two of sodium methoxide, sodium ethoxide, and sodium tert-butoxide.

[0043] As an optional implementation, the catalyst is selected from any one or a combination of at least two of potassium methoxide, potassium ethoxide, and potassium tert-butoxide.

[0044] In a preferred embodiment, the catalyst is potassium hydroxide and / or sodium hydroxide.

[0045] In a more preferred embodiment, the catalyst is sodium hydroxide.

[0046] As an optional implementation, the molar ratio of the catalyst to 2-methyl-butyraldehyde is (1~5):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, etc.

[0047] In a preferred embodiment, the molar ratio of the catalyst to 2-methyl-butyraldehyde is (1~2):1.

[0048] As an optional implementation, the alcohol-based organic solvent is selected from alcohol-based solvents.

[0049] As an optional embodiment, the alcohol organic solvent is a straight-chain or branched alkyl alcohol of C1 to C10 (e.g., C1, C2, C4, C6, C8, C10, etc.), such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, n-pentanol, sec-pentanol, isopentanol, tert-pentanol, neopentanol, n-hexanol, sec-hexanol, isohexanol, tert-hexanol, neohexanol, etc.

[0050] In a preferred embodiment, the alcoholic organic solvent is a C1-C4 straight-chain or branched alkyl alcohol.

[0051] As an optional implementation, the alcoholic organic solvent is selected from any one or a combination of at least two of methanol, ethanol, isopropanol, and tert-butanol.

[0052] In a preferred embodiment, the alcoholic organic solvent is methanol and / or ethanol.

[0053] In a more preferred embodiment, the alcoholic organic solvent is ethanol.

[0054] As an optional implementation, the molar concentration of 2-methyl-butyraldehyde in the alcoholic organic solvent is 2~5 mol / L, for example, it can be 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.4 mol / L, 3.6 mol / L, 3.8 mol / L, 4 mol / L, 4.2 mol / L, 4.4 mol / L, 4.6 mol / L, 4.8 mol / L, 5 mol / L, etc.

[0055] In a preferred embodiment, the molar concentration of 2-methyl-butanal in the alcoholic organic solvent is 3-4 mol / L.

[0056] As an optional implementation, the volume ratio of water to alcoholic organic solvent is (1~5):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, etc.

[0057] In a preferred embodiment, the volume ratio of water to alcoholic organic solvent is (1.5~2):1.

[0058] In a preferred embodiment, the mixed solvent is a mixture of water and an alcohol solvent.

[0059] As an optional implementation, the volume ratio of water to alcohol solvent is (1~5):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, etc.

[0060] In a preferred embodiment, the volume ratio of water to alcohol solvent is (1.5~2):1.

[0061] As an optional implementation, the reaction is carried out in an air atmosphere.

[0062] As an optional implementation, the reaction temperature is 60~150℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, etc.

[0063] In a preferred embodiment, the reaction temperature is 80~120°C.

[0064] As an optional implementation, the reaction time is 1 to 12 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, etc.

[0065] In a preferred embodiment, the reaction time is 4 to 8 hours.

[0066] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0067] In the following embodiments, the following detection instruments were used for analysis: Agilent GC-MS 7890B+5977B, where purity is calculated based on gas chromatographic area.

[0068] Example 1 This embodiment provides a method for preparing 4-methyl-2-propylhexenal, the preparation method specifically including the following steps: At room temperature, first add n-pentanal (9.25 g), 2-methyl-butanal (9.25 g), and sodium hydroxide (5.5 g) to the reaction flask (250 mL). Then add ethanol (30 mL) and water (50 mL) to the reaction flask. After the addition is complete, stir evenly at room temperature. Transfer the reaction flask to an oil bath and react at 80 °C for 4 h.

[0069] After the reaction was completed, the reaction solution was cooled to room temperature, and samples were taken for analysis using an Agilent gas chromatography-mass spectrometry (GC-MS) system. The conversion rate of 2-methyl-butyraldehyde was 90%, and the selectivity of 4-methyl-2-propylhexenal was 95% (e.g., Figure 1 (As shown).

[0070] Example 2 This embodiment provides a method for preparing 4-methyl-2-propylhexenal, the preparation method specifically including the following steps: At room temperature, first add n-pentanal (9.25 g), 2-methyl-butanal (9.25 g), and sodium hydroxide (5.5 g) to the reaction flask (250 mL). Then add ethanol (5 mL) and water (50 mL) to the reaction flask. After the addition is complete, stir evenly at room temperature. Transfer the reaction flask to an oil bath and react at 80 °C for 4 h.

[0071] After the reaction was completed, the reaction solution was cooled to room temperature, and the results were analyzed using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument. The conversion rate of 2-methyl-butanal was 34%, and the selectivity of 4-methyl-2-propylhexenal was 50%.

[0072] Example 3 This embodiment provides a method for preparing 4-methyl-2-propylhexenal, the preparation method specifically including the following steps: At room temperature, first add n-pentanal (13.9 g), 2-methyl-butanal (9.25 g), and sodium hydroxide (5.5 g) to the reaction flask (250 mL). Then add ethanol (30 mL) and water (50 mL) to the reaction flask. After the addition is complete, stir evenly at room temperature, transfer the reaction flask to an oil bath, and react at 80 °C for 4 h.

[0073] After the reaction was completed, the reaction solution was cooled to room temperature, and the results were analyzed using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument. The conversion rate of 2-methyl-butanal was 96%, and the selectivity of 4-methyl-2-propylhexenal was 78%.

[0074] Example 4 This embodiment provides a method for preparing 4-methyl-2-propylhexenal, the preparation method specifically including the following steps: At room temperature, first add n-pentanal (9.25 g), 2-methyl-butanal (9.25 g), and sodium hydroxide (5.5 g) to the reaction flask (250 mL). Then add ethanol (40 mL) and water (50 mL) to the reaction flask. After the addition is complete, stir evenly at room temperature. Transfer the reaction flask to an oil bath and react at 80 °C for 4 h.

[0075] After the reaction was completed, the reaction solution was cooled to room temperature, and the results were analyzed using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument. The conversion rate of 2-methyl-butanal was 87%, and the selectivity of 4-methyl-2-propylhexenal was 93%.

[0076] Example 5 This embodiment provides a method for preparing 4-methyl-2-propylhexenal, the preparation method specifically including the following steps: At room temperature, first add n-pentanal (9.25 g), 2-methyl-butanal (9.25 g), and sodium hydroxide (5.5 g) to the reaction flask (250 mL). Then add ethanol (30 mL) and water (50 mL) to the reaction flask. After the addition is complete, stir evenly at room temperature, transfer the reaction flask to an oil bath, and react at 60 °C for 4 h.

[0077] After the reaction was completed, the reaction solution was cooled to room temperature, and the results were analyzed using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument. The conversion rate of 2-methyl-butanal was 26%, and the selectivity of 4-methyl-2-propylhexenal was 41%.

[0078] Example 6 This embodiment provides a method for preparing 4-methyl-2-propylhexenal, the preparation method specifically including the following steps: At room temperature, first add n-pentanal (9.25 g), 2-methyl-butanal (9.25 g), and sodium hydroxide (2.75 g) to the reaction flask (250 mL). Then add ethanol (30 mL) and water (50 mL) to the reaction flask. After the addition is complete, stir evenly at room temperature, transfer the reaction flask to an oil bath, and react at 80°C for 4 h.

[0079] After the reaction was completed, the reaction solution was cooled to room temperature, and the results were analyzed using an Agilent gas chromatography-mass spectrometry (GC-MS) instrument. The conversion rate of 2-methyl-butanal was 44%, and the selectivity of 4-methyl-2-propylhexenal was 61%.

[0080] Examples 7-12, Comparative Examples 1-3 Except for the different catalysts used, Examples 7-12, Comparative Examples 1-3 were identical to Example 1 in all other operations, with the only difference being the choice of catalyst. The catalysts used in each example, the conversion rate of 2-methyl-butyraldehyde, and the product selectivity are shown in Table 1 below: Table 1

[0081] As shown in Table 1, the experimental results clearly indicate that the reaction is dependent on the choice of alkaline catalyst: (1) the reaction system hardly undergoes any conversion under catalyst-free conditions; (2) only when a strong base (such as hydroxides, sodium / potassium alkoxy compounds) is used can the conversion rate of raw materials and the selectivity of the target product be significantly improved; (3) the reaction system hardly undergoes any conversion due to insufficient base strength (such as sodium carbonate, sodium bicarbonate), confirming the threshold requirement of the reaction for the base dissociation ability. Further comparison revealed that sodium hydroxide in the water-alcohol mixed medium has suitable base strength, good dissolution kinetics, low side reaction tendency and excellent process compatibility. Therefore, considering the raw material conversion rate, product selectivity, ease of operation and convenient post-processing, sodium hydroxide is the best catalyst.

[0082] Examples 13-15, Comparative Examples 4-7 Except for the different catalysts used, Examples 13-15, Comparative Examples 4-7 were identical to Example 1 in all other operations, except for the choice of mixed solvent. The mixed solvents used in each example, the conversion rate of 2-methyl-butyraldehyde, and the product selectivity are shown in Table 2 below: Table 2

[0083] As shown in Table 2, the experimental results clearly demonstrate that neither a single aqueous phase nor a pure organic phase can simultaneously achieve both reactivity and selectivity. However, a mixed solvent composed of water and alcohols (especially ethanol) can synergistically exert a dual effect: the aqueous phase regulates base strength, stabilizes intermediates, and suppresses side reactions; while ethanol optimizes the solubility and molecular diffusion of the two aldehydes, promoting effective collisions. Its moderate polarity, protonicity, and miscibility with water ensure a homogeneous and stable reaction system, significantly improving cross-condensation selectivity and conversion efficiency, thus making it the optimal solvent choice.

[0084] In addition, in Examples 1 to 15: (1) the optimal range of the molar ratio of catalyst to 2-methyl-butyraldehyde is (1~2):1; (2) the optimal range of the molar concentration of 2-methyl-butyraldehyde in the organic solvent is 3~4 mol / L; (3) the optimal range of the volume ratio of water to alcohol in the reaction solvent is (1.5~2):1; (4) the optimal range of the reaction temperature is 80~120℃ and the optimal range of the reaction time is 4~8 h.

[0085] In summary, the specific reaction system of this invention can catalyze the cross-condensation reaction of n-pentanal and 2-methyl-butanal to prepare 4-methyl-2-propylhexenal with high selectivity. This method features high reactant conversion, mild reaction conditions, high product selectivity, simple separation, and convenient operation. The 4-methyl-2-propylhexenal prepared by this method is suitable for large-scale industrial production and represents an extension of the full-scale industrialization of hydroformylation of mixed C4 olefins to produce higher alcohols.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing 4-methyl-2-propylhexenal, characterized in that, The preparation method includes: Using n-pentanal and 2-methyl-butanal as reaction substrates, the reaction was carried out in a catalyst and a mixed solvent to obtain 4-methyl-2-propylhexenal; The catalyst is selected from alkali metal hydroxides and / or alkali metal alkoxides, and the mixed solvent includes water and alcohol organic solvents.

2. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The molar ratio of n-pentanal to 2-methyl-butanal is (1~5):1, preferably (1~1.5):

1.

3. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The alkali metal hydroxide is selected from any one or a combination of at least two of potassium hydroxide, sodium hydroxide, and lithium hydroxide, preferably potassium hydroxide and / or sodium hydroxide, and more preferably sodium hydroxide; Preferably, the alkali metal alkoxide is selected from sodium alkoxide and / or potassium alkoxide; Preferably, the sodium alkoxide is selected from any one or a combination of at least two of sodium methoxide, sodium ethoxide, and sodium tert-butoxide; Preferably, the potassium alkoxide is selected from any one or a combination of at least two of potassium methoxide, potassium ethoxide, and potassium tert-butoxide.

4. The method for preparing 4-methyl-2-propylhexenal according to claim 1 or 3, characterized in that, The molar ratio of the catalyst to 2-methylbutyraldehyde is (1~5):1, preferably (1~2):

1.

5. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The alcohol organic solvent is a C1-C10 straight-chain or branched alkyl alcohol, more preferably a C1-C4 straight-chain or branched alkyl alcohol. Preferably, the alcoholic organic solvent is selected from any one or a combination of at least two of methanol, ethanol, isopropanol, and tert-butanol, preferably methanol and / or ethanol, and more preferably ethanol.

6. The method for preparing 4-methyl-2-propylhexenal according to claim 1 or 5, characterized in that, The molar concentration of 2-methyl-butanal in the alcoholic organic solvent is 2-5 mol / L, preferably 3-4 mol / L.

7. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The volume ratio of water to alcoholic organic solvent is (1~5):1, preferably (1.5~2):

1.

8. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The reaction takes place in an air atmosphere.

9. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The reaction temperature is 60~150℃, preferably 80~120℃.

10. The method for preparing 4-methyl-2-propylhexenal according to claim 1, characterized in that, The reaction time is 1 to 12 hours, preferably 4 to 8 hours.

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