Method for preparing alpha-olefin through isomerization of internal olefin

Abstract

The invention discloses a method for preparing alpha-olefin by isomerization of internal olefin, which comprises the following steps: step 1, under the catalysis of a metal platinum catalyst, reacting linear internal olefin with chlorosilane to obtain n-alkyl chlorosilane; and step 2, adding villiaumite and an organic solvent into the n-alkylchlorosilane for reaction, then adding an oxidant and a metal palladium catalyst for reaction, and after the reaction is finished, performing centrifugal separation to obtain alpha-olefin. The method has the advantages of easily available reaction raw materials and mild reaction conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of olefin isomerization, and specifically relates to a method for preparing alpha-olefin by isomerizing internal olefin. Background Art

[0002] Linear α-olefins (LAO) refer to monoolefins with double bonds at the ends of the molecular chain, with the general structural formula RCH=CH2, where R is a linear alkyl group. As an important organic raw material, LAO has developed rapidly in recent years. Among them, widely used products include 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, etc. Among them, 1-decene is mainly used to produce synthetic lubricant base oil, comonomers, detergents, plasticizers and other fine chemical raw materials, and has broad development prospects. Up to now, there is no device and process technology in the world that can produce 1-decene alone. 1-Decene is usually a by-product in the process technology of preparing α-olefins such as 1-hexene and 1-octene by ethylene polymerization, and then high-purity 1-decene can be obtained by distillation separation. However, the above method is troubled by the difficulty in separating specific linear α-olefins or the separation conditions are high. Moreover, ethylene itself is a very expensive raw material, which will lead to a high price for the linear α-olefins obtained by ethylene polymerization.

[0003] Patent CN1487908A establishes a method for synthesizing higher α-olefins with a specific number of carbon atoms, using transition metal oxides loaded on γ-Al2O3 and other mixed carriers as catalysts for olefin metathesis to synthesize higher linear internal olefins, and finally preparing higher linear α-olefins through alkyl aluminum reaction. In the step of alkyl aluminum catalytic replacement to prepare α-olefins, this method requires high pressure conditions to achieve the ideal reaction conversion rate of alkyl aluminum, and the process has high requirements on reaction conditions.

[0004] Patent US5550303A describes a highly active olefin replacement reaction, which uses internal olefins and trialkylaluminum at 280-300°C to prepare linear α-olefins without a catalyst, but this process requires the temperature to drop rapidly to 120°C to reduce terminal olefin isomerization and other side reactions. Higher reaction conditions are required. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing alpha-olefins by isomerizing internal olefins, wherein the reaction raw materials are readily available and the reaction conditions are mild.

[0006] To achieve the above object, the present invention provides a method for preparing α-olefins by isomerization of internal olefins, comprising the following steps:

[0007] Step 1, under the catalysis of a metal platinum catalyst, a linear internal olefin is reacted with a chlorosilane to obtain a normal alkyl chlorosilane;

[0008] Step 2, adding fluoride salt and organic solvent to n-alkylchlorosilane for reaction, then adding oxidant and metal palladium catalyst for reaction, and after the reaction, centrifugally separating to obtain α-olefin.

[0009] In the method for preparing α-olefins by isomerizing internal olefins of the present invention, in step 1, the reaction conditions of the linear internal olefin and the chlorosilane are 80-160° C. for 12 h to 48 h, preferably the reaction temperature is 100-160° C., most preferably 130-150° C., preferably the reaction time is 16-32 h, and more preferably 16-24 h. The molar ratio of the linear internal olefin to the chlorosilane is 1:1 to 1:5, preferably 1:2-1:5, and most preferably 1:2-1:3.5, and the amount of platinum catalyst is 0.5-8 mol%, preferably 0.5-4 mol%, and more preferably 0.5-1 mol% of the linear internal olefin.

[0010] In the method for preparing α-olefins by isomerizing internal olefins of the present invention, the reaction conditions of the fluoride salt and the n-alkylchlorosilane in step 2 are 20-30°C for 15min-1h, and the reaction conditions after adding the metal palladium catalyst are 60-160°C for 1-24h, preferably the reaction temperature is 80-120°C, most preferably 100°C, and the preferred reaction time is 1-6h, most preferably 3-6h.

[0011] In the method for preparing α-olefins by isomerizing internal olefins of the present invention, the molar ratio of the linear internal olefin to the fluoride salt is 1:2-1:12, preferably 1:6-1:12, and most preferably 1:10-1:12. The amount of the metal palladium catalyst used is 6-30 mol%, preferably 18-30 mol%, and most preferably 22-30 mol% of the linear internal olefin. The molar ratio of the linear internal olefin to the oxidant is 1:1-1:5, preferably 1:3-1:5, and most preferably 1:4-1:5.

[0012] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the reactions in step 1 and step 2 are both carried out under the protection of an inert gas, and the inert gas is at least one of helium, nitrogen and argon.

[0013] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the linear internal olefins are selected from C5-C20 internal olefins.

[0014] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the metal platinum catalyst is hexachloroplatinic acid and / or bis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)platinum, preferably hexachloroplatinic acid.

[0015] In the method for preparing α-olefins by isomerizing internal olefins of the present invention, the chlorosilane is at least one of trichlorosilane, methyldichlorosilane and dimethylchlorosilane, preferably trichlorosilane, methyldichlorosilane, and most preferably trichlorosilane.

[0016] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the fluoride salt is one or more of tetrabutylammonium fluoride, cesium fluoride and potassium fluoride, preferably cesium fluoride.

[0017] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the metal palladium catalyst is one or more of palladium chloride, palladium acetate and tetrakis(triphenylphosphine)palladium, preferably palladium acetate and / or tetrakis(triphenylphosphine)palladium, more preferably tetrakis(triphenylphosphine)palladium.

[0018] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the oxidant is one or more of p-benzoquinone, cupric chloride, hydrogen peroxide and peroxybenzoic acid, preferably p-benzoquinone and / or hydrogen peroxide, and more preferably p-benzoquinone.

[0019] In the method for preparing α-olefins by isomerization of internal olefins of the present invention, the organic solvent is a polar or non-polar solvent, preferably one or more of tetrahydrofuran, dichloromethane, N-methylpyrrolidone, methanol, oxadiazine, toluene and ethyl acetate, more preferably one or more of tetrahydrofuran, dichloromethane and oxadiazine, most preferably oxadiazine and / or tetrahydrofuran.

[0020] Beneficial effects of the present invention:

[0021] The invention combines a dehydrogenation silylation reaction catalyzed by a metal palladium catalyst with a chain-type hydrosilylation reaction to convert straight-chain internal olefins into normal alpha-olefins, and has the characteristics of easy availability of reaction raw materials, mild reaction conditions, fast reaction speed, and excellent conversion rate and selectivity. DETAILED DESCRIPTION

[0022] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0023] All chemicals used in the preparations were from commercial sources and used without further purification unless otherwise stated.

[0024] Chain-type hydrosilation and dehydrogenation were carried out under argon atmosphere. All solvents used were dried using standard procedures. Liquid chemicals were stored separately after Na washing or other drying materials and 4A molecular sieves (final water content was about 3 ppm).

[0025] Chemicals such as tetrahydrofuran, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, tetrakis(triphenylphosphine)palladium, trichlorosilane, etc. were purchased from Macklin, Aladdin, etc. and used after further purification. The obtained products were characterized by gas chromatography-mass spectrometry.

[0026] Example 1: Isomerization of 4-octene to 1-octene

[0027] In a glove box filled with argon, add 1 mmol of 4-octene and 0.005 mmol of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum and 1 mmol of trichlorosilane to a pressure bottle. After reacting at 80°C for 12 hours, the reaction mixture is cooled to room temperature and evacuated to remove excess trichlorosilane. The Schlenk flask is then backfilled with argon and transferred to an argon-filled glove box, where 1 ml of tetrahydrofuran and 2 mmol of cesium fluoride are added to the Schlenk flask. The mixture is stirred at 20°C for 1 hour. 2 ml of tetrahydrofuran, 1 mmol of p-benzoquinone and 0.06 mmol of tetrakis(triphenylphosphine)palladium are added to the mixture. React at 60°C for 1 hour, cool to room temperature, and analyze the organic phase by GC to determine the content of 1-octene.

[0028] 4-octene conversion: 28.7%, 1-octene selectivity: 40.1%;

[0029] Example 2: Isomerization of 5-decene to 1-decene.

[0030] In a glove box filled with argon, add 1 mmol of 5-decene and 0.08 mmol of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum and 5 mmol of trichlorosilane to a pressure bottle. After reacting at 160°C for 48 hours, the reaction mixture is cooled to room temperature and evacuated to remove excess trichlorosilane. The Schlenk flask is then backfilled with argon and transferred to an argon-filled glove box. In the argon-filled glove box, 1 ml of tetrahydrofuran and 2 mmol of cesium fluoride are added to the Schlenk flask. Stir the mixture at 30°C for 15 minutes. Add 2 ml of tetrahydrofuran, 5 mmol of p-benzoquinone and 0.3 mmol of tetrakis(triphenylphosphine)palladium to the mixture. React at 160°C for 24 hours, cool to room temperature, analyze the organic phase by GC, and determine the content of 1-decene.

[0031] 5-decene conversion: 35.0%, 1-decene selectivity: 41.3%;

[0032] Example 3: Isomerization of 6-dodecene to 1-dodecene

[0033] In a glove box filled with argon, add 1 mmol of 6-dodecene and 0.01 mmol of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum and 2 mmol of trichlorosilane to a pressure bottle. After reacting at 130°C for 24 hours, the reaction mixture is cooled to room temperature and evacuated to remove excess trichlorosilane. The Schlenk flask is then backfilled with argon and transferred to an argon-filled glove box, where 1 ml of tetrahydrofuran and 10 mmol of cesium fluoride are added to the Schlenk flask. The mixture is stirred at 20°C for 1 hour. 2 ml of tetrahydrofuran, 4 mmol of p-benzoquinone and 0.3 mmol of tetrakis(triphenylphosphine)palladium are added to the mixture. React at 80°C for 6 hours, cool to room temperature, and analyze the organic phase by GC to determine the content of 1-dodecene.

[0034] 6-dodecene conversion: 47.5%, 1-dodecene selectivity: 78.3%;

[0035] Example 4: Isomerization of 7-tetradecene to 1-tetradecene

[0036] In a glove box filled with argon, 1 mmol of 7-tetradecene and 0.005 mmol of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum and 3.5 mmol of trichlorosilane were added to a pressure bottle. After reacting at 150°C for 16 hours, the reaction mixture was cooled to room temperature and vacuumed to remove excess trichlorosilane. The Schlenk flask was then backfilled with argon and transferred to an argon-filled glove box, where 1 ml of tetrahydrofuran and 12 mmol of cesium fluoride were added to the Schlenk flask. The mixture was stirred at 25°C for 1 hour. 2 ml of tetrahydrofuran, 5 mmol of p-benzoquinone and 0.22 mmol of trisdibenzylideneacetone dipalladium were added to the mixture. The mixture was reacted at 120°C for 3 hours, cooled to room temperature, and the organic phase was analyzed by GC to determine the content of 1-tetradecene.

[0037] 7-Tetradecene conversion: 39.6%, 1-Tetradecene selectivity: 72.1%.

[0038] Example 5: Isomerization of 4-octene to 1-octene

[0039] In a glove box filled with argon, hexachloroplatinic acid was dissolved in tetrahydrofuran solution to prepare chloroplatinic acid-tetrahydrofuran solution, and 1mmol of 4-octene, 0.01mmol of chloroplatinic acid-tetrahydrofuran solution and 2mmol of trichlorosilane were added to a pressure bottle. After reacting at 140°C for 24h, the reaction mixture was cooled to room temperature and vacuumed to remove excess trichlorosilane. The Schlenk flask was then backfilled with argon and transferred to an argon-filled glove box, where 1ml of tetrahydrofuran and 10mmol of cesium fluoride were added to the Schlenk flask. The mixture was stirred at 25°C for 15 minutes. 2ml of tetrahydrofuran, 4mmol of p-benzoquinone and 0.3mmol of palladium acetate were added to the mixture. The mixture was reacted at 100°C for 1h, cooled to room temperature, and the organic phase was analyzed by GC to determine the content of 1-octene.

[0040] 4-octene conversion: 62.6%, 1-octene selectivity: 73.1%;

[0041] Example 6: Isomerization of 5-decene to 1-decene.

[0042] In a glove box filled with argon, hexachloroplatinic acid was dissolved in tetrahydrofuran solution to prepare chloroplatinic acid-tetrahydrofuran solution, and 1mmol of 5-decene, 0.01mmol of chloroplatinic acid-tetrahydrofuran solution and 3mmol of trichlorosilane were added to a pressure bottle. After reacting at 140°C for 24h, the reaction mixture was cooled to room temperature and vacuumed to remove excess trichlorosilane. The Schlenk flask was then backfilled with argon and transferred to an argon-filled glove box, where 1ml of tetrahydrofuran and 12mmol of cesium fluoride were added to the Schlenk flask. The mixture was stirred at 25°C for 15 minutes. 2ml of tetrahydrofuran, 5mmol of p-benzoquinone and 0.3mmol of palladium acetate were added to the mixture. The reaction was carried out at 100°C for 6h, cooled to room temperature, and the organic phase was analyzed by GC to determine the content of 1-decene.

[0043] 5-decene conversion: 60.0%, 1-decene selectivity: 88.0%;

[0044] Example 7: Isomerization of 6-dodecene to 1-dodecene

[0045] In a glove box filled with argon, hexachloroplatinic acid was dissolved in tetrahydrofuran solution to prepare chloroplatinic acid-tetrahydrofuran solution, and 1mmol of 6-dodecene and 0.01mmol of chloroplatinic acid-tetrahydrofuran solution and 3.5mmol of trichlorosilane were added to a pressure bottle. After reacting at 140°C for 24h, the reaction mixture was cooled to room temperature and vacuumed to remove excess trichlorosilane. The Schlenk flask was then backfilled with argon and transferred to an argon-filled glove box, where 1ml of tetrahydrofuran and 10mmol of cesium fluoride were added to the Schlenk flask. The mixture was stirred at 20°C for 15 minutes. 2ml of tetrahydrofuran, 4mmol of p-benzoquinone and 0.3mmol of palladium acetate were added to the mixture. The mixture was reacted at 100°C for 6h, cooled to room temperature, and the organic phase was analyzed by GC to determine the content of 1-dodecene.

[0046] 6-dodecene conversion: 33.6%, 1-dodecene selectivity: 53.4%;

[0047] Example 8: Isomerization of 7-tetradecene to 1-tetradecene

[0048] In a glove box filled with argon, hexachloroplatinic acid was dissolved in tetrahydrofuran solution to prepare chloroplatinic acid-tetrahydrofuran solution, and 1mmol of 7-tetradecene and 0.01mmol of chloroplatinic acid-tetrahydrofuran solution and 2mmol of trichlorosilane were added to a pressure bottle. After reacting at 130°C for 24h, the reaction mixture was cooled to room temperature and vacuumed to remove excess trichlorosilane. The Schlenk flask was then backfilled with argon and transferred to an argon-filled glove box, where 1ml of tetrahydrofuran and 11mmol of cesium fluoride were added to the Schlenk flask. The mixture was stirred at 30°C for 15 minutes. 2ml of tetrahydrofuran, 4mmol of p-benzoquinone and 0.3mmol of palladium acetate were added to the mixture. The reaction was carried out at 100°C for 6h, cooled to room temperature, and the organic phase was analyzed by GC to determine the content of 1-tetradecene.

[0049] 7-Tetradecene conversion: 16.8%, 1-Tetradecene selectivity: 57.3%.

[0050] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing α-olefins by isomerization of internal olefins, characterized in that: The following steps are involved: Step 1, under the catalysis of a metal platinum catalyst, a linear internal olefin is reacted with a chlorosilane to obtain a normal alkyl chlorosilane; Step 2, adding fluoride salt and organic solvent to n-alkylchlorosilane for reaction, then adding oxidant and metal palladium catalyst for reaction, and after the reaction, centrifugally separating to obtain α-olefin.

2. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: In step 1, the reaction conditions of the linear internal olefin and chlorosilane are 80-160° C. for 12 h-48 h, the molar ratio of the linear internal olefin to the chlorosilane is 1:1 to 1:5, and the amount of platinum catalyst is 0.5-8 mol% of the linear internal olefin.

3. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The reaction conditions of the fluoride salt and n-alkyl chlorosilane in step 2 are 20-30° C. for 15 min-1 h, and the reaction conditions after adding the metal palladium catalyst are 60-160° C. for 1-24 h.

4. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The molar ratio of the linear internal olefin to the fluoride salt is 1:2-1:12, the amount of the metal palladium catalyst is 6-30 mol% of the linear internal olefin, and the molar ratio of the linear internal olefin to the oxidant is 1:1-1:

5.

5. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The reactions in step 1 and step 2 are both carried out under the protection of an inert gas, wherein the inert gas is at least one of helium, nitrogen and argon.

6. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The linear internal olefin is selected from C5-C20 internal olefins.

7. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The metal platinum catalyst is hexachloroplatinic acid and / or bis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)platinum.

8. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The chlorosilane is at least one of trichlorosilane, methyldichlorosilane and dimethylchlorosilane.

9. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The fluoride salt is one or more of tetrabutylammonium fluoride, cesium fluoride and potassium fluoride.

10. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The metal palladium catalyst is one or more of palladium chloride, palladium acetate and tetrakis(triphenylphosphine)palladium.

11. The method for preparing α-olefins by isomerization of internal olefins according to claim 1, characterized in that: The oxidant is one or more of p-benzoquinone, cupric chloride, hydrogen peroxide and peroxybenzoic acid.