Method for obtaining long-chain linear alkenes

Abstract

The invention relates to a method for obtaining a linear, internal C₁₀-C₁₆ alkene from a non-substituted linear, terminal C₁₀-C₁₆ alkene in the presence of a metal precursor. Figure 1

Description

[0001] DESCRIPTION

[0002] Procedure for obtaining long-chain linear alkyls

[0003] The present invention relates to a process for obtaining long-chain linear aiquenes characterized by being useful for application as lubricants and in the paper industry.

[0004] BACKGROUND OF THE INVENTION

[0005] Unsubstituted long-chain internal aiquenes are fundamental chemical compounds in the industrial manufacturing chain, however, their synthesis remains expensive and limits subsequent transformations.

[0006] This is because the most direct and easiest way to synthesize an internal alkene—i.e., the migration of a double bond to the desired internal position from the inexpensive and widely available terminal alkene to obtain a clean internal alkene—is still unsolved at both the research and industrial levels. Thus, double bond migration technology in aikenes cannot yet meet the needs for preparing simple internal aikenes.

[0007] Currently, the isomerization of unsubstituted long chain alkenes is carried out in industry with basic solids, at temperatures between 200 - 450 °C and in continuous flow, which generally produces a mixture of alkenes with some branched products after a conversion of 80-90%. (US patent 3723564, 1973; US patent 6281404 B1, 2001; US ​​patent 5801293 A1, 1998) In this mixture of different internal components, the expected migration positions (2, 3, 4, etc.) are obtained in addition to the corresponding cis and trans stereoisomers for each alkene (see comments below), giving a final mixture that may contain 2 (n - 1) isomers for a given n alkyl chain alkene.The fine composition! is not detailed in any previous patent (see for example: US 5801293 A1). As an example, only the isomerization of short-chain gaseous aiquenes, such as 1-butene, described to date, allow a cis / trans ratio of 1 : 2 to 2-butene after an 80% conversion, which is a poor yield, around 50% for pure trans-2-butene. This conversion value is not acceptable for many applications of the corresponding unsubstituted long-chain aiquenes, such as lubrication or paper sizing. For example, long-chain lubricants require at least a conversion > 95% (<5% starting terminal olefin), with no branches in the final product; otherwise, the lubricating properties are lost and the desired final product becomes solid and does not remain liquid.

[0008] Current double bond migration processes in petroleum-derived terminal alkenes take advantage of the production of terminal alkenes in flow, known as normal alpha olefin (NAO) technology, to connect the two processes. The prior art does not describe examples of unsubstituted long-chain terminal alkenes, i.e., those with more than eight carbons to be considered a long-chain linear alkene (see, for example, US 8324423 B2).

[0009] On the other hand, to date, terminal olefins from the NAO process require additional purification (by distillation) before entering the migration process, otherwise the catalyst is rapidly deactivated (US 3723564).

[0010] Furthermore, double bond migration in unsubstituted long-chain terminal alkenes obtained from petrochemicals is not an optimized process; it requires expensive catalysts, energy-intensive processes, and results in incomplete conversions and product mixtures that include significant amounts of branched and saturated alkenes, which are detrimental to the final mixture.

[0011] Isomerization of terminal olefins to internal olefins with solid catalysts in flow has also been described, with conversions of around 98%, using silicoalumina as catalyst at 75-150 °C. (US 2005 / 0070747 A1) As a result the isomer distribution is quite broad, and the process requires recirculation of the product mixture for typically 4 hours to achieve a process yield of 20 kilograms of product per kilogram of catalyst, which is insufficient for flexible, efficient and inexpensive industrial production.

[0012] There are also studies on the use of solid-supported metals as double bond migration catalysts, including long-chain linear terminal alkenes (see US 3352939; and US 3409702). However, these solid catalysts require the use of mixtures of metals or aldehydes as additives, and in quantities of thousands of parts per million, with partial conversions (around 68%), which makes them unviable for industrial purposes. Double bond migration in terminal alkenes has also been studied with homogeneous catalysts in solution. These catalysts can be basic or acidic.

[0013] KOH and NaOH have been used as basic homogeneous solution catalysts for the isomerization of simple alkenes in combination with iron (ChemSusChem 2012, 5, 734-739) or alumina (Eur. Pat.

[0014] Appl. (1988), EP 279397 A1 19880824; Ger. Offen. (1972), DE 2137024 A 19720127). However, these bases typically have to be used in very large (often stoichiometric) quantities, exhibit long reaction times, generate caustic residues, and give incomplete conversion in many cases. Furthermore, these strong bases are particularly unsuitable for the downstream application of petroleum-derived long-chain linear internal alkenes, since any trace of base remaining in the final mixture will render the alkene unfit for further acid-catalyzed reactions such as hydroadditions, Friedel-Crafts, or epoxidations.

[0015] Soluble acid catalysts based on metal complexes have been studied more than basic ones, and although these systems have higher conversions and selectivities (up to 99% in both cases) than solid catalysts and have opened new routes for the synthesis of in-house alkenes in laboratories, they show clear drawbacks for industrial implementation, such as stoichiometric additives, high amount of solvent and unacceptable loading of metal catalyst, typically 0.5-10 mol %, which provides inaccessible prices for a real industrial process (Science 383, 391-396, 2019; ChemCatChem 9, 3849-3859, 2017; Chem. Rev. 103, 27-51, 2003; J. Organomet. Chem. 86, C17, 1975; J. Mol. Cal 11, 293-300, 1981).There are examples of soluble Ru catalysts in very low amounts for certain long chain alkenes, however, it requires the use of very expensive and toxic carbon monoxide complexes, in addition to the need for a carbon monoxide atmosphere in some cases, which makes these catalytic systems not only economically less attractive but also dangerous and not recommended from a sustainability and safety point of view (WO2014 / 1508211; US ​​9708236 B2).

[0016] Thus, a process that significantly improves the efficiency and selectivity of migration from terminal to internal long-chain double bonds would be desirable for industrial-scale production.

[0017] DESCRIPTION OF THE INVENTION

[0018] In a first aspect, the invention relates to a process for obtaining a C 10 -C 16internal and linear alkene comprising the following steps: i) mixing of a C 10 -C 16 a linear, unsubstituted terminal alkene with a supported or unsupported metal precursor; and ii) heating the mixture obtained in step (i) to a temperature of between 150 °C and 300 °C, where the metal precursor gives rise to the in situ formation of isolated metal atoms that act as catalysts, characterized in that:

[0019] - the metal precursor is used in an amount less than 100 ppm by weight with respect to C 10 -C 16 terminal, linear, unsubstituted alkene.

[0020] Thus, the process of the present invention makes it possible to obtain long-chain linear internal aiquenes, of between 10 and 16 unsubstituted and unbranched carbon atoms, preferably between 12 and 14 unsubstituted and unbranched carbon atoms, by means of migration of the double bond in the corresponding terminal aiquenes, in the presence of a metallic catalyst, supported or not, of the VIH and IX groups in homeopathic quantities (less than 100 parts per million), in the absence of external reducers, such as H2 or aldehydes, and in the absence of pre-reduced soluble catalysts, such as hydrides or carbon monoxide. On the other hand, the process is preferably carried out without a solvent. The aiquenes C 10 -C 16They are preferred for isomerization due to their unique hydrophobicity and density properties. Furthermore, the reaction proceeds more efficiently with alkanes of lower or higher carbon counts because they poison the catalyst less in both cases.

[0021] In another embodiment the invention relates to the process described above, where steps (i) and (ii) are carried out in the absence of solvent.

[0022] In another embodiment, the invention relates to the process described above, which further comprises a step (iii) of isolating the product obtained in step (ii).

[0023] The isolation step (iii) referred to in the present invention consists of the recovery of the final product, since the elimination of any additive or by-product is not required.

[0024] In another embodiment the invention relates to the method described above, where the C 10 -C16 The terminal, linear, unsubstituted alkene of step (i) is a C 12 -C 14 terminal, linear, unsubstituted alkene, and more preferably where the C 10 -C 16 The terminal, linear, unsubstituted alkene of step (i) is selected from 1-dodecene and 1-tetradecene.

[0025] In another embodiment, the invention relates to the process described above, where the metallic precursor of step (i) is selected from salts, complexes, nanoparticles and macroscopic forms of metals from groups VIII and IX of the periodic table or a mixture thereof.

[0026] In another embodiment, the invention relates to the process described above, where the metal of the metallic precursor of step (i) is from group VIII of the periodic table, and preferably where the metal of the metallic precursor of step (i) is from group VIII of the periodic table and is selected from Fe, Ru, Os and a mixture thereof.

[0027] In another embodiment, the invention relates to the process described above, where the metal of the metallic precursor of step (i) is from group IX of the periodic table, and preferably where the metal of the metallic precursor of step (i) is from group IX of the periodic table and is selected from Co, Rh, Ir and a mixture thereof.

[0028] In another embodiment, the invention relates to the process described above where the metal of the metal precursor of step (i) is selected from Fe, Ru, Os, Co, Rh, Ir and combinations thereof, preferably selected from Fe, Ru and a mixture thereof, and more preferably where the precursor metal of step (i) is Ru.

[0029] In another embodiment the invention relates to the process described above where the metal of the metal precursor of step (i) is Ru(lll), Ru(M) or Ru(O).

[0030] In another embodiment the invention relates to the process defined above where the metal precursor is selected from Ru3(CO) 12 , RuCl3, Ru(C4H8)2COD, Ru(PPh)3Cl2, Ru nanoparticles in colloidal form and Ru nanoparticles as pure metal. Throughout the invention, nanoparticles (NPs) in colloidal form refer to nanoparticles stabilized by surfactants. Examples include, but are not limited to, carboxylic acids, carbenes, thiols and ammonium salts.

[0031] Nanoparticles (NPs) as pure metal refer to nanoparticles that must be supported.

[0032] In another embodiment, the invention relates to the process defined above, wherein the metal precursor is supported on inorganic oxides, and preferably wherein the inorganic oxides are selected from alumina, titania, silica, zinc oxide, zirconium oxide, nanoceria; activated carbon and / or combinations thereof.

[0033] In another embodiment, the invention relates to the process defined above, where the metal precursor is a Ru salt that is optionally reduced.

[0034] In another embodiment, the invention relates to the process defined above where the metal precursor is supported on activated carbon.

[0035] In another embodiment the invention relates to the method described above where the C 10 -C 16 The terminal, linear, unsubstituted alkene of step (i) is present in an amount of between 10,000 equivalents and 100,000,000 equivalents relative to the metal precursor, preferably between 1,000,000 equivalents and 10,000,000 equivalents relative to the metal precursor, and more preferably between 2,000,000 equivalents and 5,000,000 equivalents relative to the metal precursor.

[0036] In another embodiment, the invention relates to the process defined above where the metal precursor is used in an amount of between 1 ppm and 100 ppm by weight with respect to C. 10 -C 16 terminal, linear, unsubstituted alkene, preferably between 1 ppm and 50 ppm by weight with respect to C 10 -C 16 terminal, linear, unsubstituted alkene, and more preferably between 1 and 10 ppm by weight with respect to C 10 -C 16 terminal, linear, unsubstituted alkene.

[0037] In another embodiment, the invention relates to the process defined above, wherein step (ii) of the process is carried out in a simple stirred batch reactor or in a continuous stirred-tank reactor with continuous flow or fixed bed, and preferably in a simple stirred batch reactor. Throughout the invention, the term "batch" refers to a stationary, batch reactor.

[0038] In another embodiment, the invention relates to the process defined above, where the temperature of step (ii) is between 200 °C and 250 °C, and more preferably at a temperature of 200 °C.

[0039] In another embodiment, the invention relates to the process defined above where step (ii) is carried out at a pressure of between 1 bar and 20 bar, and preferably 1 bar.

[0040] In another embodiment, the invention relates to the process defined above, where step (ii) is carried out under an inert or ambient atmosphere, preferably under an inert atmosphere of nitrogen, helium or argon, more preferably under a nitrogen atmosphere.

[0041] Throughout the invention the term “ambient atmosphere” refers to carrying it out in air, not under an inert atmosphere.

[0042] In another embodiment, the invention relates to the process defined above where step (ii) is carried out in the presence of organic solvents, and preferably in the presence of aromatic solvents.

[0043] In another embodiment, the invention relates to the process defined above where the reaction time of step (ii) is between 0.5 h and 72 h, and preferably between 1 h and 24 b.

[0044] In another embodiment the invention relates to the process defined above where: C 10 -C 16 The unsubstituted, linear, terminal alkene in step (i) is 1-dodecene; the metal precursor in step (i) is Ru; and the temperature in step (ii) is 200 °C.

[0045] In another embodiment the invention relates to the method defined above where: C 10 -C 16The unsubstituted, linear, terminal alkene of step (i) is 1-dodecene; the metal precursor of step (i) is Ru; the temperature of step (i¡) is 200 °C; and step (ii) is carried out under an inert nitrogen atmosphere;

[0046] In another embodiment the invention relates to the process defined above where: C 10 -C 16 The unsubstituted, linear, terminal alkene of step (i) is 1-dodecene; the metal precursor of step (i) is Ru; the temperature of step (ii) is 200 °C; step (ii) is carried out under an inert nitrogen atmosphere; the reaction time is 4.5 h; and the reaction pressure is 1 bar.

[0047] In another embodiment the invention relates to the method defined above where: C 10 -C 16 The unsubstituted, linear, terminal alkene from step (i) is 1-tetradecene; the metal precursor from step (i) is Ru,

[0048] In another embodiment the invention relates to the method defined above where: C 10 -C 16 The unsubstituted, linear, terminal alkene in step (i) is 1-tetradecene; the metal precursor in step (i) is Ru; and the temperature in step (ii) is 200 °C.

[0049] In another embodiment the invention relates to the process defined above where: C 10 -C 16 The unsubstituted, linear, terminal alkene of step (i) is 1-tetradecene; the metal precursor of step (i) is Ru; the temperature of step (ii) is 200 °C; step (ii) is carried out under an inert nitrogen atmosphere; the reaction time is 5 h; and the reaction pressure is 1 bar.

[0050] Throughout the present invention, the term “C 10 -C 16“unsubstituted, linear, terminal alkene” refers to an alkene of 10 to 16 carbon atoms that is unbranched and unsubstituted and has a terminal double bond. Examples include 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, and 1-hexadecene.

[0051] The term “metal precursor” refers to salts, complexes, nanoparticles and macroscopic forms of metals that may be solid-supported or unsupported, which give rise to the in situ formation of extremely active isolated metal atoms useful as catalysts to carry out C double bond migration. 10 -C 16 terminal, linear, unsubstituted alkene without the need for solvents. The solid may be an inorganic oxide such as alumina, zeolites, or silica. Examples include, among others, metals from groups VIH and IX of the periodic table, such as Fe, Ru, Os, Co, Rh, and Ir.

[0052] The in situ formed catalyst used in the process of the invention relies on the use of extremely small amounts, typically parts per million (ppm).

[0053] The structural characteristics of C alkenes 10 -C 16 The internal, linear and unsubstituted components obtained by the process of the invention make them useful in the lubricant and paper processing industries.

[0054] Throughout the description and claims, the word "comprises" and its variants are not intended to exclude other technical features, additives, components, or steps. For those skilled in the art, other objects, advantages, and features of the invention will be apparent partly from the description and partly from the practice of the invention. The following examples and figures are provided for illustrative purposes only and are not intended to be limiting of the present invention.

[0055] BRIEF DESCRIPTION OF THE FIGURES

[0056] Fig. 1 shows the 1 H NMR spectrum of the starting 1-dodecene (A) and the reaction product (B) after 4.5 h of reaction with 0.0005 mol% of Ru(C4H8)2(COD).

[0057] Fig. 2 shows the 1 H NMR spectrum of the starting 1-tetradecene (A) and the reaction product (B) after 4.5 h of reaction with 0.0005 mol% of Ru(C4H8)2(COD).

[0058] EXAMPLES The invention will now be illustrated by tests carried out by the inventors, which demonstrate the effectiveness of the product of the invention.

[0059] Table 1 shows the results with 1-dodecene for a typical Ru catalyst. Double bond migration occurs with only 5 ppm w / w of Ru catalyst (entry 6) at >95% conversion, albeit with a prolonged reaction time (20 h). This linear alkyl chain terminal olefin has a boiling point above 200 °C and good thermal stability, allowing its possible conversion to internal alkenes at temperatures above 150 °C and with better conversions in less time. Table 1 also shows that, at 200 °C, isomerization continues at >97% conversions after 4.5 h. It is worth mentioning here that, depending on the amount of catalyst, the mixture of internal alkenes is different. For example, using 1 ppm w / w of catalyst there is 72% 2-dodecene and 18% other more internal alkenes, and at 5 ppm w / w there is 26% 2-dodecene. The results are consistent for starting materials (1-dodecene) from several commercial houses.In any case, the final mixture of linear internal alkenes is consistent for a given amount of catalyst. Table 1

[0060] Table 2 shows the results for 1-tetradecene at reaction temperatures of 150 and 200 °C. As evaluated above for 1-dodecene, higher conversions are obtained in less time at 200 °C, with a conversion >97% at 5 ppm wt Ru after 5 b. It should be noted that a conversion >95% is difficult to obtain with any industrial method and is very beneficial for the final application of the product. Example 1: Procedure for migration of the double bond in 1-dodecene with 5 ppm by weight of the Ru(C4H8)2COD catalyst.

[0061] 1-Dodecene (27 g) was charged into a 50 ml flask equipped with a magnetic stirrer, and the catalyst Ru(methallyl)2COD (0.0005 mol %) was added. The flask was closed with a septum, filled with nitrogen, and placed in an oil bath preheated to 200 °C under magnetic stirring for a given reaction time. Aliquots of the reaction mixture were taken to monitor the reaction over time by GC and NMR. It should be noted that stock solutions of the Ru catalyst were prepared in dichloromethane (which evaporates during the reaction) since the quantities used are too small to be weighed. To prepare these solutions, volumetric flasks with dichloromethane as the solvent were used. For analysis by GC, 5.6 μl of the reaction mixture was diluted with 1 ml of ethyl acetate.For NMR analysis, 20 mg of the reaction mixture was dissolved in deuterated chloroform (CDCI3 signal: singlet, 7.26 ppm), and 15 mg of 1,2-didoroethane (signal: singlet, 3.73 ppm) was added as an internal standard to calculate the reaction conversion. Figure 1 shows how the starting terminal olefin disappears and the desired products appear.

[0062] Example 2: Double bond migration procedure in 1-tetradecene with 5 ppm by weight of the Ru(C4H8)2COD catalyst.

[0063] 1-Tetradecene (32 g) was charged into a 50 ml flask equipped with a magnetic stirrer and the catalyst Ru(methallyl)2COD (0.0005 mol %) was added. The flask was closed with a septum, a nitrogen atmosphere was created and the mixture was placed in an oil bath preheated to 200 °C under magnetic stirring for a given reaction time. Aliquots of the reaction mixture were taken to follow the reaction over time by GC and NMR. It should be noted that stock solutions of the Ru catalyst were prepared in dichloromethane (which evaporates during the reaction) since the quantities used are too small to be weighed. To prepare these solutions, volumetric flasks with dichloromethane as the solvent were used. For analysis by GC, 5.6 µl of the reaction mixture was diluted with 1 ml of ethyl acetate.For NMR analysis, 20 mg of the reaction mixture was dissolved in deuterated chloroform (CDCI3 signal: singe, 7.26 ppm); 15 mg of 1,2-dichloroethane (signal: singe, 3.73 ppm) was also added as an internal standard to calculate the reaction conversion. Figure 2 shows how the starting terminal olefin disappears and the desired products appear.

[0064] Example 3: Procedure for migration of the double bond in 1-dodecene in a stirred tank with a solid Ru catalyst on silica.

[0065] A solid Ru-on-silica catalyst, prepared by impregnation of RuCl3 onto high surface area silica for a final loading of 1 wt% Ru, was added into a 50 ml flask equipped with a magnetic stirrer to obtain 0.001 mol% of Ru relative to the 1-dodecene (27 g), which was then added. The flask was closed with a septum, provided with a nitrogen atmosphere, and placed in an oil bath preheated to 200 °C under magnetic stirring for a given reaction time. After stopping the stirring, samples of the supernatant were taken to monitor the reaction over time by GC and NMR. For NMR analysis, 20 mg of the supernatant was dissolved in deuterated chloroform (CDCI3 signal: singlet, 7.26 ppm), also, 15 mg of 1,2-dichloroethane (signal: singlet, 3.73 ppm) was added as an internal standard to calculate the conversion of the reaction.

Claims

CLAIMS 1. A procedure for obtaining a C 10 -C 16 Internal and linear aichene comprising the following stages: i) mixing of a C 10 -C 16 (i) linear, unsubstituted, terminated alkene with a supported or unsupported metal precursor; and (ii) heating the mixture obtained in step (i) to a temperature between 150 °C and 300 °C, wherein the metal precursor gives rise to the in situ formation of isolated metal atoms that act as catalysts, characterized in that: - the metallic precursor is used in an amount less than 100 ppm by weight with respect to ai C 10 -C 16 terminal, linear, unsubstituted aikene, where: steps (i) and (ii) are carried out in the absence of solvent, and the metal of the metallic precursor of step (i) is Ru.

2. The process according to claim 1, wherein the C 10 -C 16The terminal, linear, unsubstituted aiquene of stage (i) is a C 12 -C 14 aiqueno termina!, linear and not replaced.

3. The process according to any of claims 1 or 2, wherein the C 12 -C 14 The terminal, linear, unsubstituted aiquene of step (i) is selected from 1-dodecene and 1-tetradecene.

4. The process according to any of claims 1 to 3, wherein the metallic precursor is selected from Ru3(CO) 12 , RuCl3, Ru(C4H8)2COD, Ru(PPh)3Cl2, Ru nanoparticles in colloidal form and Ru nanoparticles as pure metal.

5. The process according to any of claims 1 to 4, wherein the metallic precursor is supported on inorganic oxides.

6. The process according to any of claims 1 to 5, wherein the C 10 -C 16The terminal, linear, unsubstituted aiquene of step (i) is present in an amount of between 10,000 equivalents and 100,000,000 equivalents with respect to the metallic precursor.

7. The process according to any one of claims 1 to 6, wherein the metal precursor is used in an amount of between 1 ppm and 100 ppm by weight with respect to the linear, unsubstituted, terminal Cium-Cus alkene.

8. The process according to any one of claims 1 to 7, wherein the step (ii) is carried out in a batch reactor with simple stirring or in a continuous stirred tank reactor with continuous flow or fixed bed.

9. The process according to any of claims 1 to 8, wherein the temperature of step (ii) is between 200 °C and 250 °C.

10. The process according to any one of claims 1 to 9, wherein step (ii) is carried out at a pressure of between 1 bar and 20 bar.

11. The process according to any one of claims 1 to 10, wherein step (ii) is carried out under an inert atmosphere 12. The process according to any of claims 1 to 11, wherein the reaction time of step (ii) is between 0.5 h and 72 h.