Method for preparing 1-methoxy-2, 7-octadiene

Abstract

The invention discloses a method for preparing 1-methoxy-2, 7-octadiene, belongs to the technical field of chemical engineering, and solves the problem that the reaction efficiency of corresponding preparation reaction in the prior art is not ideal enough. The method comprises the following steps: in an oxygen-free environment, dissolving a palladium source and a palladium source ligand in methanol, adding acetic acid as a stabilizer, and stirring at normal temperature to obtain a catalyst prefabricated solution; and sequentially adding methanol, a catalyst and 1, 3-butadiene into the catalyst prefabricated liquid, carrying out telomerization reaction under an anaerobic condition, cooling to room temperature after the reaction is finished, and releasing pressure to obtain the 1-methoxy-2, 7-octadiene. The palladium catalytic system obtained by the preparation method is high in 1, 3-butadiene conversion rate, better in ligand selectivity and lower in catalyst concentration, and can be used for industrial production of 1-MOD.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, and more specifically to a method for preparing 1-methoxy-2,7-octadiene. Background Art

[0002] The telomerization of 1,3-butadiene with methanol is a key step in the commercial route to produce 1-octene reported in the literature. The telomerization product 1-methoxy-2,7-octadiene (1-MOD) is fully hydrogenated to 1-methoxyoctane, which is then thermally cracked to obtain the desired product oct-1-ene and recyclable methanol. In addition to 1-MOD, two major by-products are formed: 3-methoxy-1,7-octadiene (3-MOD) and 1,3,7-octatriene (OCT).

[0003] The generation of 1-MOD by the reaction of 1,3-butadiene and methanol with palladium catalysts is considered to be the key step in the synthesis of 1-octene. Although a three-step method for the synthesis of 1-octene based on 1,3-butadiene and methanol as raw materials has been developed using a Pd / PPh3 catalytic system and put into production in 2008, industrial and academic laboratories are still conducting in-depth research on the development of palladium catalysts with higher activity and regioselectivity under milder conditions. n-Heterocyclic carbene and triarylphosphine are the two main ligands of palladium catalysts.

[0004] Compared with the excellent performance of the (NHC)Pd catalyst developed by Beller et al., the catalytic performance of Pd-phosphine complexes was relatively poor until the synthesis of bukly-type phosphine ligands by van Leeuwen et al. in 2010, which brought a huge leap in catalyst efficiency. Since phosphine ligands have more stable performance than NHC ligands under commercially relevant production conditions when using industrial raw materials, the development of more efficient phosphine ligands for the polymerization of 1,3-butadiene with methanol remains a promising prospect. Summary of the invention

[0005] The invention provides a method for preparing 1-methoxy-2,7-octadiene, which is used to solve the problem that the reaction efficiency of the corresponding preparation reaction in the prior art is not ideal.

[0006] In a first aspect, the present invention provides a method for preparing 1-methoxy-2,7-octadiene, comprising the following steps: in an oxygen-free environment, dissolving a palladium source and a palladium source ligand in methanol, adding acetic acid as a stabilizer and stirring at room temperature to obtain a catalyst prefabricated liquid; sequentially adding methanol, a sodium methoxide catalyst and 1,3-butadiene to the catalyst prefabricated liquid, carrying out a telomerization reaction under oxygen-free conditions, cooling to room temperature after the reaction is completed and then releasing the pressure to obtain the 1-methoxy-2,7-octadiene, wherein the palladium source ligand is any one of formula (1), formula (2), formula (3), formula (4), formula (5) and formula (6),

[0007]

[0008] As a possible implementation, the palladium source is any one of di(acetylacetone)palladium, palladium chloride, tetrakis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium and bis(dibenzylideneacetone)palladium.

[0009] As a possible implementation method, the reaction conditions of the telomerization reaction are: temperature 50-90° C., initial pressure ≥0.80 MPa, and duration 1-48 h.

[0010] As a possible implementation manner, the palladium source concentration is 0.00065 mol% to 0.0025 mol%; and / or the methanol water content is 0 to 240 ppm.

[0011] As a possible implementation manner, the palladium source ligand is twice the equivalent of the palladium source; and / or the acetic acid is one time the equivalent of the palladium source.

[0012] As a possible implementation manner, the conversion rate of 1,3-butadiene is 60% to 95%; the selectivity of 1-methoxy-2,7-octadiene is 89% to 95%.

[0013] In a second aspect, the present invention provides 1-methoxy-2,7-octadiene prepared by the method described in any possible implementation of the first aspect.

[0014] In a third aspect, the present invention provides a use of 1-methoxy-2,7-octadiene as described in any possible implementation of the second aspect in the preparation of 1-octene.

[0015] The main purpose of the present invention is to provide an efficient catalyst system for the telomerization reaction of 1,3-butadiene and methanol. The palladium catalytic system obtained by the preparation method of the present invention has a high 1,3-butadiene conversion rate, better ligand selectivity and lower catalyst concentration, and can be used for industrial production of 1-MOD. In order to achieve the above purpose, the present invention synthesizes the series of ligands, obtains the parent of xanthene by reacting p-tert-butylphenol with acetone under the catalysis of trifluoromethanesulfonic acid, and further obtains the final series of ligands after bromination and lithiation of different diaryl phosphines. In order to achieve the above purpose, the present invention provides a series of ligands, which have a high butadiene conversion rate (60% to 95%) and high 1-MOD selectivity (89% to 95%) for the reaction at low concentrations (5 to 50 ppm). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the mass spectrum of 1-methoxy-2,7-octadiene provided in an embodiment of the present invention.

[0018] Figure 2 A schematic diagram of the hydrogen nuclear magnetic resonance spectrum of 1-methoxy-2,7-octadiene provided in an embodiment of the present invention.

[0019] Figure 3 Schematic diagram of gas chromatography of the product of Experiment III provided in an embodiment of the present invention.

[0020] Figure 4 Schematic diagram of gas chromatography of the product of Experiment IX provided in an embodiment of the present invention.

[0021] Figure 5 Schematic diagram of gas chromatography of the product of Experiment X provided in an embodiment of the present invention.

[0022] Figure 6 Schematic diagram of gas chromatography of the product of Experiment XIII provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In order to solve the problem that the reaction efficiency of the corresponding preparation reaction in the prior art is not ideal, this embodiment provides a preparation experiment of 1-methoxy-2,7-octadiene and statistics on the conversion rate of butadiene and the selectivity of 1-MOD.

[0025] It can be seen that the palladium catalytic system obtained by the preparation method of the present invention has a high conversion rate of 1,3-butadiene, better selectivity of the ligand and lower catalyst concentration, and can be used for industrial production of 1-MOD. The present invention synthesizes this series of ligands, and obtains xanthene by reacting p-tert-butylphenol with acetone under the catalysis of trifluoromethanesulfonic acid. The present invention provides a series of ligands, which have a high butadiene conversion rate (70% to 95%) and high 1-MOD selectivity (89% to 95%) for the reaction at low concentrations (5 to 50 ppm).

[0026] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0027] Example 1

[0028] This example provides a preparation experiment of 1-methoxy-2,7-octadiene.

[0029] The preparation experiment provided in this embodiment includes the following steps: after two gas exchanges with low-pressure high-purity nitrogen, the autoclave is evacuated to negative pressure (-0.09 MPa); sodium methoxide (0.01-0.5 mol%) is dissolved in methanol (1-10 wt%) (sodium methoxide is used as a promoter to provide an alkaline environment for the reaction, and methanol is used as both a solvent and a reactant) and introduced into the autoclave through negative pressure. In this embodiment, methanol is dried over a 3A molecular sieve, and the water content is 10-200 ppm; the reaction kettle is heated to 40 ℃ and the temperature is 40 ℃. The temperature is lowered to -20 to 0°C, 1,3-butadiene (30 to 300 g) is frozen into liquid in a -40°C cold bath, and introduced into the autoclave by negative pressure; a catalyst prefabricated liquid is added by negative pressure [the preparation method comprises the steps of: dissolving a palladium source (0.0001 to 0.01 mol%) and two equivalents of a ligand in about 50 g of methanol, and adding one equivalent of acetic acid as a stabilizer and stirring at room temperature for half an hour]; the temperature is gradually increased, and timing is performed after reaching the temperature; the temperature is lowered after the reaction time is reached, and the reaction is terminated.

[0030]

[0031] Experiment I: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1) (0.005 mol%) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 0.64 MPa by nitrogen; the reaction was carried out for 2.5 hours, and the temperature was lowered after the time was reached; when the temperature was lowered to 25°C, the pressure was released to normal pressure. The product was analyzed by mass spectrometry, and the following was obtained: Figure 1 The results shown in the figure were analyzed by nuclear magnetic resonance hydrogen spectrum, and the following Figure 2 From the results shown, it can be seen that 1-methoxy-2,7-octadiene was successfully prepared.

[0032] Experiment II: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1) (0.005 mol%) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 0.88 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased with time to 0.67 MPa, and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure.

[0033] Experiment III: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1) (0.005 mol%) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 1.03 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased to 0.82 MPa over time, and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure. The product was analyzed by gas chromatography, and the following was obtained: Figure 3 Results shown.

[0034] Experiment IV: Pd(OAc)2 (0.0025 mol%, 15 mg) was used as the palladium source, and formula (1) (0.005 mol%, 52 mg) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 0.96 MPa by nitrogen, and the reaction was carried out for 2.5 hours. After the time was reached, the temperature was lowered; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0035]

[0036] Experiment V: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1a) (0.005 mol%, 90 mg) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 1.00 MPa by nitrogen, and the reaction was carried out for 4 hours. After the time was reached, the temperature was lowered; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0037] Experiment VI: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (2a) (0.005 mol%, 52 mg) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 1.00 MPa by nitrogen, and the reaction was carried out for 4 hours. After the time was reached, the temperature was lowered; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0038] Experiment VII: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (3a) (0.005 mol%, 52 mg) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 1.13 MPa by nitrogen, and the reaction was carried out for 2.5 hours. After the time was reached, the temperature was lowered; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0039] Experiment VIII: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1) (0.005 mol%) was used as the ligand; when the reaction reached 80°C, the reaction pressure was increased to 1.03 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased with time to 0.75 MPa, and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure.

[0040] Experiment IX: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1) (0.005 mol%, 67 mg) was used as the ligand; when the reaction reached 70°C, the reaction pressure was increased to 1.01 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased to 0.71 MPa over time, and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure. The product was analyzed by gas chromatography, and the following was obtained: Figure 4 Results shown.

[0041] Experiment X: Pd(acac)2 (0.0025 mol%, 20 mg) was used as the palladium source, and formula (1) (0.005 mol%, 67 mg) was used as the ligand; when the reaction reached 60°C, the reaction pressure was increased to 0.89 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased to 0.78 MPa over time, and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure. The product was analyzed by gas chromatography, and the following was obtained: Figure 5 Results shown.

[0042] Experiment ⅩⅠ: Pd(acac)2 (0.00125 mol%, 10 mg) was used as the palladium source and formula (1) (0.0025 mol%) was used as the ligand; when the reaction reached 90°C, the reaction pressure was increased to 1.20 MPa by nitrogen and the reaction was carried out for 2.5 h. During the reaction, the pressure decreased with time to 0.97 MPa and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure.

[0043] Experiment ⅩⅡ: Pd(acac)2 (0.000625 mol%, 10 mg) was used as the palladium source, formula (1a) (0.00125 mol%) was used as the ligand, and butadiene (5.32 mol, 288 g) was used; when the reaction reached 90°C, the reaction pressure was increased to 1.36 MPa by nitrogen, and the reaction was carried out for 5 hours. During the reaction, the pressure decreased with time to 1.22 MPa, and the temperature was lowered after the time was reached; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0044] Experiment XIII: Pd(acac)2 (0.000625 mol%, 10 mg) was used as the palladium source, formula (1) (0.00125 mol%) was used as the ligand, butadiene (5.32 mol, 288 g) was used; when the reaction reached 70°C, the reaction pressure was increased to 1.13 MPa by nitrogen, and the reaction was carried out for 16 hours. During the reaction, the pressure decreased to 0.85 MPa over time, and the temperature was lowered after the time was reached; when the temperature dropped to 25°C, the pressure was released to normal pressure. The product was analyzed by gas chromatography, and the following was obtained: Figure 6 Results shown.

[0045] Experiment XIV: Pd(acac)2 (0.0008 mol%, 13 mg) was used as the palladium source, formula (1) (0.00125 mol%) was used as the ligand, and butadiene (5.32 mol, 288 g) was used; when the reaction reached 70°C, the reaction pressure was increased to 1.06 MPa by nitrogen, and the reaction was carried out for 16 hours. During the reaction, the pressure decreased with time to 0.73 MPa, and the temperature was lowered after the time was reached; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0046] Experiment XV: Pd(acac)2 (0.00125 mol%, 10 mg) was used as the palladium source, formula (1) (0.0025 mol%) was used as the ligand, and methanol was used to dry through a 4A molecular sieve, with a water content of 170 ppm; when the reaction reached 90°C, the reaction pressure was increased to 1.20 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased with time to 1.07 MPa, and the temperature was lowered after the time was reached; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0047] Experiment XVI: Pd(acac)2 (0.00125 mol%, 10 mg) was used as the palladium source, formula (1) (0.0025 mol%) was used as the ligand, and undried methanol (water content was 210-240 ppm) was used; when the reaction reached 90°C, the reaction pressure was increased to 1.30 MPa by nitrogen, and the reaction was carried out for 2.5 hours. During the reaction, the pressure decreased with time to 1.15 MPa, and the temperature was lowered after the time was reached; when the temperature was lowered to 25°C, the pressure was released to normal pressure.

[0048] The target product peak was determined by fitting GC-MS, the selectivity was obtained by comparing the integrated area of ​​the GC peak, and the conversion rate of butadiene was calculated by the weight gain of the reaction solution. The three groups of experiments were calculated separately and the results shown in Table 1 were obtained.

[0049] Table 1 Parameters and results of each group of experiments

[0050]

[0051] From the comparison of Experiment Ⅰ (pressure 0.64Mpa), Experiment Ⅱ (pressure 0.88~0.67Mpa) and Experiment Ⅲ (pressure 1.03~0.82Mpa) in Table 1, it can be seen that within a certain range, the conversion rate of butadiene is positively correlated with the reaction pressure. From the comparison of Experiment Ⅲ (palladium source Pd(acac)2) and Experiment Ⅳ (palladium source Pd(OAc)2) in Table 1, it can be seen that within a certain range, the conversion rate of butadiene is related to the selection of palladium source. From the comparison of Experiment III [ligand formula (1)], Experiment V [ligand formula (1a)], Experiment VI [ligand formula (2a)] and Experiment VII [ligand formula (3a)] in Table 1, it can be seen that within a certain range, the conversion rate of butadiene is related to the selection of the ligand; from Experiment V, it can be seen that although the ligand formula (1a) has excellent performance in terms of conversion rate, it is not conducive to the selectivity of 1-MOD; from Experiment VI, it can be seen that although the ligand formula (2a) has excellent performance in terms of 1-MOD selectivity, it is not conducive to the conversion rate; from Experiment VII, it can be seen that the ligand formula (3a) performs poorly in terms of both conversion rate and 1-MOD selectivity. From the comparison of Experiment III (temperature 90°C), Experiment VIII (temperature 80°C), Experiment IX (temperature 70°C) and Experiment X (temperature 60°C) in Table 1, it can be seen that within a certain range, the selectivity of 1-MOD is negatively correlated with the temperature; when the temperature is lower than 70°C, the conversion rate is significantly reduced. From the comparison of Experiment III (palladium source concentration 0.0025mol%), Experiment XI (palladium source concentration 0.00125mol%), Experiment XII (palladium source concentration 0.000625mol%), Experiment XIII (palladium source concentration 0.000625mol%) and Experiment XIV (palladium source concentration 0.0008mol%) in Table 1, it can be seen that within a certain range, the conversion rate of butadiene is related to the concentration of the palladium source; when the palladium source concentration is lower than 0.0008mol%, the conversion rate of butadiene is significantly reduced. From the comparison of Experiment ⅩⅠ (methanol water content 0), Experiment ⅩV (methanol water content 170 ppm) and Experiment ⅩVI (methanol water content 210-240 ppm) in Table 1, it can be seen that within a certain range, the conversion rate of butadiene is related to the methanol water content. When the methanol water content is higher than 170 ppm, the conversion rate of butadiene is significantly reduced.

[0052] It can be seen that increasing the reaction pressure (initial pressure ≥ 0.80Mpa) is conducive to improving the butadiene conversion rate, selecting a reasonable reaction temperature range (70-90°C) is conducive to improving the reaction selectivity and conversion rate, selecting a reasonable palladium source concentration range (0.0008mol%-0.0025mol%) is conducive to improving the reaction conversion rate, and reducing the water content of methanol (<170ppm) is conducive to improving the reaction conversion rate. The present invention combines the above factors, by adjusting the concentration of palladium to reduce the process cost, at 70°C, only 8ppm of palladium can make the butadiene conversion rate of the reaction reach 87.1%, and the selectivity can reach 93.0%.

[0053] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0054] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing 1-methoxy-2,7-octadiene, characterized in that: The following steps are involved: In an oxygen-free environment, a palladium source and a palladium source ligand are dissolved in methanol, and acetic acid is added as a stabilizer and stirred at room temperature to obtain a catalyst prefabricated liquid; Methanol, sodium methoxide catalyst and 1,3-butadiene are sequentially added to the catalyst prefabricated liquid, and a telomerization reaction is carried out under anaerobic conditions. After the reaction is completed, the temperature is lowered to room temperature and the pressure is released to obtain the 1-methoxy-2,7-octadiene, wherein the palladium source ligand is any one of formula (1), formula (2), formula (3), formula (4), formula (5) and formula (6), 2. The method according to claim 1, characterized in that The palladium source is any one of di(acetylacetone)palladium, palladium chloride, tetrakis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium and bis(dibenzylideneacetone)palladium.

3. The method according to claim 1, characterized in that The reaction conditions of the telomerization reaction are: temperature 50-90° C., initial pressure ≥0.80 MPa, and duration 1-48 h.

4. The method according to claim 1, characterized in that: The palladium source concentration is 0.00065mol% to 0.0025mol%; And / or, the methanol water content is 0 to 240 ppm.

5. The method according to claim 1, characterized in that The palladium source ligand is twice the equivalent of the palladium source; And / or, the acetic acid is one equivalent of the palladium source.

6. The method according to any one of claims 1 to 5, characterized in that: The conversion rate of 1,3-butadiene is 60% to 95%; The selectivity of the 1-methoxy-2,7-octadiene is 89% to 95%.

7. 1-Methoxy-2,7-octadiene prepared by the method according to any one of claims 1 to 6.

8. Use of the 1-methoxy-2,7-octadiene according to claim 7 in the preparation of 1-octene.

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