WO2013079820A1 - Method for metathesizing linear alpha olefins using a ruthenium complex comprising an asymmetrical n-heterocyclic carbene - Google Patents

Abstract

The invention relates to a method for metathesizing identical or different linear alpha olefins into linear internal olefins having excellent selectivity, using a ruthenium complex comprising an asymmetrical N-heterocyclic carbine as a catalyst, wherein one of the nitrogen atoms has a cycloalkyl grouping having a carbon number greater than 3 and the other nitrogen atom has an aryl grouping.

Description

 ALPHA LINEAR DOLEFINE STATEHING PROCESS USING A

 RUTHENIUM COMPLEX COMPRISING A CARBENE

 DISSYMETRIC N-HETEROCYCLIC

Field of the invention

 The present invention relates to the metathesis of alpha linear olefins, which is a catalytic reaction for olefin conversion, comprising exchanging the alkylidene groups of the starting olefins.

More particularly, the invention relates to a method of metathesis of linear alpha olefins (identical or different) to linear internal olefins using a particular catalyst according to the reaction: cross metathesis if R 'other than R "or homometathesis if R' = R ".

Study of the prior art

The metathesis reaction has become an important tool for the formation of carbon-carbon bonds. It is used in the fields of L 5 petrochemistry, polymers, oleo-chemistry and fine chemistry. Isolated carbene complexes based on ruthenium have been described to catalyze this reaction (Chem Rev, 2010, 10, 1746-1787).

WO 01/46096 discloses a process for converting C4-C10 olefins from a Fisher-Tropsch process, C6-C18 olefins using a homogeneous catalyst 10 based Grubbs type ruthenium ^(1st generation) of the formula RuCl ₂ (PCy ₃ ) ₂ (CHPh) with improved selectivity over heterogeneous catalysts known to those skilled in the art.

Ru complexes comprising a heterocyclic carbenic ligand with 5 non-symmetrical NHC members have been described by Bléchert

> 5 (Organometallics, 2006, 25, 25-28). "NHC" complex is understood to mean N-heterocyclic carbene complexes according to the Anglo-Saxon terminology "N-heterocyclic carbenes". The complexes described in Blechert have been used to catalyze cross-metathesis of olefins, but they do not show any advantage over the complexes bearing symmetrical NHC carbenes previously described by

30 Grubbs. The patent WO2011 / 056874 describes a catalytic composition based on a Ru complex comprising a dissymmetrical NHC carbene for the production of alpha olefins by metathesis of triglycerides or of fatty acids, for example for the production of decene-1 by reaction. methyl oleate with ethylene. WO2007 / 075427 discloses a ruthenium complex bearing a 5 membered NHC carbene wherein one of the nitrogen atoms is substituted by a phenyl group which contains a hydrogen in the ortho position and which is substituted in the ortho prime position. These complexes are used to catalyze olefin metathesis by ring closure (RCM). A large variety of ruthenium catalysts are described, but each of these catalysts is designed to be applied to a very specific metathesis reaction. Their transposition to another metathesis reaction is not obvious.

Moreover, the parasitic isomerization of the olefin double bond of the charge or products of metathesis very often leads to the formation of unwanted byproducts and appears to be a limitation to the economic development of these catalytic systems. The isomerization of the double bond results in a drop in selectivity to desired linear internal olefins.

It has now been found that, surprisingly, the use of a ruthenium-based 5-membered non-membered heterocyclic carbenic N (NHC) complex having specific substituents on the two carbene nitrogen atoms in a process Metathesis of linear alpha olefins provided linear internal olefins with excellent selectivity. Indeed, when the two nitrogen atoms of the heterocyclic carbene with 5 NHC members are respectively substituted by i) a cycloalkyl group whose carbon number is greater than 3 and ii) by an aryl group, then the selectivity of the reaction of Metathesis of linear alpha olefins is markedly improved. An advantage of the invention is in particular to improve the selectivity of the metathesis reaction of linear alpha olefins so as to optimize the desired olefin yield, which has the consequence of simplifying the separation of the products and of improve the overall economy of the process. Another advantage of the invention is that the process according to the invention makes it possible to obtain a good conversion of the olefins to be converted and that with very low ruthenium concentrations.

Objective of the invention

 An object of the invention is to provide a metathesis method using a catalyst system for producing linear internal olefins from linear alpha olefins, with both good conversions, low ruthenium content, and excellent selectivity to linear olefin, particularly limiting the production of other olefins by isomerization of the double bond.

Detailed description of the invention

The present invention describes a method of metathesis of alpha linear olefins to internal linear olefins using as catalyst a ruthenium complex having the formula (I) below, comprising at least one asymmetric N-heterocyclic carbene for which one of the atoms of nitrogen carries a cycloalkyl group R ⁷ having a carbon number greater than 3 and the other nitrogen atom bears an aryl group R ⁸ ,

Formula I in which :

X are identical or different and are anionic ligands,

 L is a donor ligand with 2 electrons,

Y represents a substituted or unsubstituted alkylidene, vinylidene, allenylidene or indenylidene moiety, Y optionally being able to form a ring with L,

R ³ , R ⁴ , R ⁵ and R ⁶ , which may be identical or different, are hydrogen, alkyl, cycloalkyl, aryl or arylalkyl groups, each of which may be substituted by alkyl, halide, alkoxy groups or by a phenyl group optionally substituted with halide, alkyl or alkoxy groups.

The catalyst (formula I)

The catalyst used in the process according to the invention is a dissymmetrical N-heterocyclic carbene (NHC) complex based on ruthenium. The term "asymmetric NHC complex" is understood to mean a complex in which one nitrogen atom carries a group different from the group of the other nitrogen atom. In the case of formula I, the ligand R ⁷ is therefore different from the ligand R ⁸ .

For the purposes of the present invention, R ⁷ is a cycloalkyl group having a carbon number greater than 3.

 By "cycloalkyl having a carbon number greater than 3" is meant a monocyclic hydrocarbon group having a carbon number greater than 3, preferably between 4 and 24, more preferably between 6 and 12, preferably a cyclopentyl group, cyclohexyl, cyclooctyl or cyclododecyl, or polycyclic (bicyclic or tricyclic) having a carbon number greater than 3, preferably between 4 and 18, such as, for example, adamantyl or norbornyl groups.

R ⁸ is an aryl group. By "aryl" is meant an aromatic mono- or polycyclic group, preferably mono- or bicyclic, having a carbon number between 6 and 20. Preferred aryl groups are preferably selected from phenyl, naphthyl and mesityl groups. When the group is polycyclic, that is to say it comprises more than one ring nucleus, the ring rings can advantageously be condensed two by two or attached in pairs by σ bonds.

For the purposes of the present invention, the substituents R ³ , R ⁴ , R ⁵ and R ⁶ , which are identical or different, are alkyl, cycloalkyl, aryl or arylalkyl groups, each of which may be substituted by alkyl, halide, alkoxy or a phenyl group optionally substituted with halide, alkyl or alkoxy groups. By "alkyl" substituent is meant a straight or branched hydrocarbon chain having 1 to 15 carbon atoms _, preferably having 1 to 10 carbon atoms, and even more preferably having 1 to 4 carbon atoms. Examples of preferred alkyl substituents include methyl, ethyl, propyl, isopropyl, butyl, isobutyl and t-butyl. By an "alkoxy" substituent is meant an alkyl-O- group in which the term alkyl has the meaning given above. Preferred examples of alkoxy substituents are methoxy or ethoxy.

By "alkyl" is meant for R ³ , R ⁴ , R ⁵ and R ⁶ a linear or branched hydrocarbon chain having from 1 to 15 carbon atoms, preferably from 1 to 10 and even more preferably from 1 to 4. Preferred alkyl groups are preferably selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl.

By "cycloalkyl" is meant for R ³ , R ⁴ , R ⁵ and R ⁶ a monocyclic cyclic hydrocarbon group preferably containing from 3 to 10 carbon atoms, in particular a cyclopentyl or cyclohexyl group, or a polycyclic (bicyclic or tricyclic) group. ) having from 4 to 18 carbon atoms, especially adamantyl or norbornyl. By "aryl" is meant for R ³ , R ⁴ , R ⁵ and R ⁶ an aromatic mono- or polycyclic group, preferably mono- or bicyclic having from 6 to 20 carbon atoms, preferably phenyl or naphthyl. When the group is polycyclic, that is to say that it comprises more than one ring nucleus, the ring nuclei can be condensed two by two or attached in pairs by bonds σ.

By "arylalkyl" or "aralkyl" is meant for R ³ , R ⁴ , R ⁵ and R ⁶ a linear or branched hydrocarbon-based group carrying a monocyclic aromatic ring having 7 to 12 carbon atoms, the aliphatic chain comprising 1 or 2 carbon atoms. A preferred arylalkyl or aralkyl group is benzyl.

X ligands

X is an anionic ligand advantageously chosen from halides, sulphates, alkyl sulphates, aryl sulphates, alkyl sulphonates, aryl sulphonates, alkyl sulfinates, aryl sulfinates, acyls, carbonates, carboxylates, alkoxides, phenolates, amides and the pyrolures. Said anionic ligands may advantageously be substituted or unsubstituted, preferably by one or more of the substituent groups chosen from alkyl groups having 1 to 12 carbon atoms, alcoholic groups having 1 to 12 carbon atoms, aryl groups having from 5 to 24 carbon atoms. carbon atoms and halides. Said substituent groups, with the exception of the halides, may advantageously themselves be substituted or unsubstituted by one or more of the groups chosen from halides, alkyl groups having 1 to 6 carbon atoms, and alcoholic groups having 1 to 6 carbon atoms. carbon atoms, and aryl groups.

Preferably, the X ligands are anionic ligands, which are identical or different, chosen from halide ligands, benzoates, tosylates, mesylates, trifluoromethanesulfonates, pyrolides, CF3CO2 trifluoroacetates, CH3CO2 acetates, alcoholic groups such as that CH ₃ 0, CH ₃ CH ₂ 0, (CH ₃ ) ₃ CO, (CF ₃ ) ₂ (CH ₃ ) CO, (CF ₃ ) (CH ₃ ) ₂ CO, phenolates such as C ₆ F ₅ O, C ₆ H ₅ O. Preferably, the anionic ligands X are chosen from halide ligands and very preferably the two ligands X are identical and are chlorides or bromides.

5 The ligand L

L is a donor ligand of 2 electrons. Preferably L is a phosphorus ligand of formula PR ' ₃ in which P is a phosphorus atom and R' is chosen from the groups R and (OR) in which the groups R are identical or different and are chosen from hydrogen groups, halides, alkyls,

3 cycloalkyls, aryls and arylalkyls, substituted or unsubstituted, each of groups containing up to 20 carbon atoms. The substituents of said groups may advantageously be chosen from halides, alkyl groups and aryl groups having up to 20 carbon atoms. In the case where R 'is a group OR, R' and R are not a hydrogen or a halide. In the case where R '

5 is a group R, at least one of R is not hydrogen or halogen.

The group (PR'3) is preferably chosen from phosphines and phosphites of formula PR ₃ , P (OR) ₃ , PH ₂ R, PHRR ¹ , PRR ¹ R ² and P (OR) (OR ¹ ) (OR ² ) in which the groups R, R ¹ and R ² are all identical or different and are chosen from alkyl, cycloalkyl, aryl and arylalkyl groups having

D each of 1 to 20 carbon atoms and preferably 1 to 12 carbon atoms.

Each of said groups R, R ¹ and R ² can advantageously be substituted or unsubstituted. The substituents may advantageously be chosen from halogens, preferably fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), alkyl groups and aryl groups having up to 20 atoms. carbon,

Preferably up to 12 carbon atoms and even more preferably up to 8 carbon atoms.

The phosphorus ligand (PR'3) of the ruthenium compound (I) is preferably a phosphine, preferably a tri-alkyl or tri-cycloalkyl phosphine selected from tricyclohexylphosphine, triisopropylphosphine and D tricyclopentylphosphine, a di-alkyl or a di-cycloalkyl phosphine selected from dicyclohexylphosphine, dicyclohexylphenylphosphine, di-tert-butylphosphine and di-tert-butylchlorophosphine or a tri-aryl phosphine selected from triphenylphosphine, tri (methylphenyl) phosphine, trimesitylphosphine, tri (dimethylphenyl) phosphine, tri [(trifluoromethyl) phenyl] phosphine.

In a particularly preferred manner, the catalyst used in this invention has the following formulas:

in which X is selected from chloride and bromide ligands and R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are defined as for formula I.

R ⁹ may be a hydrogen or a substituted or unsubstituted aryl group. Preferably, R ⁹ is a substituted or unsubstituted phenyl group.

 Very preferably, the ligands X are identical and are chosen from chloride or bromide ligands, L is a tricyclohexylphosphine and Y is an indenylidene group, substituted or unsubstituted.

Load

The olefins used in the process according to the invention are chosen from linear alpha-olefins. Preferably, the olefins are chosen from linear alpha-olefins having from 3 to 20 carbon atoms, preferably from 4 to 14 and more preferably from 5 to 10. For example, pentene-1, hexene-1, heptene-1, octene-1, nonene-1 or decene-.

 Linear alpha olefins can be used alone or as a mixture.

The charge may for example come from a Fischer-Tropsch process.

Catalyzing the catalyst

The amount of catalyst composition used for the metathesis reaction depends on a variety of factors such as the identity of the reagents and the reaction conditions employed. As a result, the amount of catalyst composition required will be optimally and independently defined for each reaction. However, preferably, the amount of ruthenium complex relative to olefins, expressed in moles, is between 1 and 10,000 ppm, preferably between 1 and 200 ppm and particularly preferably between 1 and 100 ppm.

The process

The olefin metathesis process according to the invention may advantageously be carried out in the absence or in the presence of a solvent. Where appropriate, solvents which can be used according to the process of the invention can be chosen from organic solvents, protic solvents or water. The solvents that can be used for the metathesis according to the present invention can for example be chosen from aromatic hydrocarbons such as benzene, toluene and xylenes, halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene, aliphatic hydrocarbons such as pentane, hexane, heptane and cyclohexane, chlorinated alkanes such as dichloromethane, chloroform and 1,2-dichloroethane, ethers such as diethyl ether and tetrahydrofuran, alcohols such as methanol and ethanol or the water. A preferred solvent is chlorobenzene. The combinations of these solvents can also be advantageously used. Any amount of solvent may advantageously be employed, but the use of at least the minimum amount required for the dissolution of the compound of formula (I) is preferred and such a minimum amount is readily determined by those skilled in the art. The volume of the solvent may be very small relative to the volume of olefin reactants employed.

Said metathesis process for olefins according to the invention is advantageously carried out under vigorous stirring, insofar as it allows good contact between the reagents (which may be gaseous for some) and said catalytic composition.

Said metathesis process of the olefins according to the invention can advantageously be carried out under a nitrogen or argon atmosphere, preferably at atmospheric pressure. Generally, a wide range of temperatures can be used. Said metathesis process for olefins according to the invention is advantageously carried out at a temperature of between 0 ° C. and 80 ° C., and preferably between 20 ° C. and 150 ° C.

The pressure of the reaction is advantageously between atmospheric pressure and 10 MPa (100 bar) and preferably between atmospheric pressure and 3 MPa (30 bar). If the reagent is gaseous, it is advantageously used pure or in admixture or diluted with an inert paraffin.

Said method for metathesis of the olefins according to the invention can advantageously be carried out as well in a closed system (batch), as in a semi-open system or in a continuous system, and with one or more reaction stages.

Generally, the reaction time or residence time in a continuous reaction for the olefin metathesis process according to the invention is preferably from about one second to about one day, preferably about five minutes to about 10 hours. The invention will be further explained in the light of the illustrative examples given below which demonstrate the advantages of the catalyst compositions and the process according to the invention. The examples below illustrate the invention without limiting its scope.

Examples

EXAMPLE 1 Process for metathesis of octene-1 with the catalyst A bearing a symmetrical NHC (not in accordance with the invention)

Metathesis of octene-1 was performed with a symmetrical NHC carbene complex of the following structure:

 Catalyst A

In a reaction tube provided with a magnetized bar and under an argon atmosphere, the required quantity of catalyst A in solution in 0.5 ml of dichloromethane is introduced. Still under argon flow, 200 mg of dodecane, used as internal standard, are added. The heating set point is set to the desired temperature (50 or 80 ° C). When the set temperature is reached, 5 ml of octene-1 is added, freshly distilled and filtered on basic alumina, and then degassed before the test, which corresponds to the time t = 0 of the reaction. At the end of the reaction, the reaction medium is neutralized with a few drops of butyl vinyl ether and diluted in heptane before analysis by gas chromatography.

The conversion of octene-1 is calculated with the following formula:

((starting mole octene - mole octene-final) / mole octene-1 starting) ^* 100 The tetradecene selectivity is calculated with the following formula:

((mole tetradecene ^* 2) / (mole octene-1 starting - mole octene-1 final)) ^* 100

The results after 4 hours of test are shown in the table below.

EXAMPLE 2 Method of Metathesis of Octene-1 with Catalyst B Bearing a Symmetric NHC (Not in Accordance with the Invention)

 Catalyst B

The metathesis reaction of octene-1 is carried out as in Example 1 using Catalyst B in place of Catalyst A.

 The results after 4 hours of test are shown in the table below.

EXAMPLE 3 Method of Metathesis of Octene-1 with Catalyst C Bearing an Unsymmetrical NHC (in Accordance with the Invention)

 Catalyst C

 The metathesis reaction of octene-1 is carried out as in Example 1 using Catalyst C in place of Catalyst A.

The results after 4 hours of test are shown in the table below. Table: Results of the Catalytic Tests Described in Examples 1-3

It is observed that the process according to the invention makes it possible to obtain, from octene, tetradecene (C14) with a selectivity of 99%, greater than that obtained with the known catalysts. This excellent selectivity allows easier separation of the product and easy recycling of unreacted olefin.

Claims

Process for the metathesis of alpha linear olefins to internal linear olefins using as catalyst a ruthenium complex having the formula (I) below, comprising at least one asymmetric N-heterocyclic carbene for which one of the nitrogen atoms bears a cycloalkyl group R ⁷ having a carbon number greater than 3 and the other nitrogen atom carrying an R ⁸ aryl group,

 Formula I in which :  X are identical or different and are anionic ligands,  L is a donor ligand with 2 electrons,  Y represents a substituted or unsubstituted alkylidene, vinylidene, allenylidene or indenylidene moiety, Y optionally being able to form a ring with L, R ³ , R ⁴ , R ⁵ and R ⁶ , which may be identical or different, are hydrogen, alkyl, cycloalkyl, aryl or arylalkyl groups, each of which may be substituted by alkyl, halide, alkoxy groups or by a phenyl group optionally substituted with halide, alkyl or alkoxy groups. The process according to claim 1 wherein R ⁷ is a monocyclic cycloalkyl group having a carbon number between 4 and 24, or polycyclic having a carbon number between 4 and 18. Process according to one of the preceding claims wherein R ⁸ is an aromatic mono- or polycyclic group having a carbon number between 6 and 20. Process according to one of the preceding claims, in which R ³ , R ⁴ , R ⁵ and R ⁶ are identical or different, and are chosen from  a linear or branched alkyl group having from 1 to 15 carbon atoms, a monocyclic cycloalkyl group having from 3 to 10 carbon atoms, or polycyclic group having from 4 to 18 carbon atoms,  an aromatic mono- or bicyclic group having from 6 to 20 carbon atoms,  a linear or branched arylalkyl group carrying a monocyclic aromatic ring having from 7 to 12 carbon atoms, the aliphatic chain comprising 1 or 2 carbon atoms. Process according to one of the preceding claims, in which X is an anionic ligand chosen from haiogenides, sulphates, alkyl sulphates, aryl sulphates, alkyl sulphonates, aryl sulphonates, alkyl sulfinates, aryl sulfinates, acyls, carbonates and carboxylates. alkoxides, phenolates, amides and pyrolides, substituted or not by one or more groups chosen from alkyl groups having from 1 to 12 carbon atoms, alcoholic groups containing from 1 to 12 carbon atoms, aryl groups having from 5 to 24 carbon atoms and haiogenures, said substituent groups, with the exception of haiogenures, themselves being substituted or not by one or more of the groups selected from the haiogenures, the alkyl groups having from 1 to 6 carbon atoms, carbon, alkoxide groups having 1 to 6 carbon atoms, and aryl groups. Process according to the preceding claim wherein X is chosen from halide ligands, benzoates, tosylates, mesylates, trifluoromethanesulfonates, pyrolides, CF ₃ CO ₂ trifluoroacetate groups, CH ₃ CO ₂ acetates, alcoholates and phenolates. Process according to one of the preceding claims, in which L is a phosphorus ligand of formula PR'3 in which P is a phosphorus atom and R 'is chosen from the groups R and (OR) in which the R groups are identical or different. and are chosen from substituted or unsubstituted hydrogen, halide, alkyl, cycloalkyl, aryl and arylalkyl groups, each of groups containing up to 20 carbon atoms, the substituents of said groups are chosen from halides, alkyl groups and aryl groups having up to 20 carbon atoms, and in the case where R 'is a group OR, R 'and R are not hydrogen or a halide, and in the case where R' is a group R, at least one of R is not hydrogen or halogen. 8. Process according to the preceding claim, in which L is a trialkyl or tri-cycloalkylphosphine chosen from tricyclohexylphosphines, triisopropylphosphines and tricyclopentylphosphines, a di-alkyl or a di-cycloalkylphosphine chosen from dicyclohexylphosphines and dicyclohexylphenylphosphines. di-tert-butylphosphines and di-tert-butylchlorophosphines or a tri-aryl phosphine chosen from triphenylphosphine, tri (methylphenyl) phosphine, trimesitylphosphine, tri (dimethylphenyl) phosphine, tri [(trifluoromethyl) phenyl] phosphine . 9. The method of claim 1 wherein the X ligands are identical and are selected from chlorides ligands or bromides, L is a tricyclohexylphoshine and Y is a substituted or unsubstituted indenylidene group. 10. Process according to one of the preceding claims wherein the olefins are chosen from linear alpha-olefins having from 3 to 20 carbon atoms, alone or as a mixture. 1 1. Process according to the preceding claim, in which the olefin is chosen from pentene, hexene, heptene, octene, nonene-1 or decene. 12. Method according to one of the preceding claims wherein the amount of ruthenium complex relative to olefins, expressed in moles, is between 1 and 0000 ppm. 13. Process according to one of the preceding claims, carried out in the presence of a solvent chosen from aromatic hydrocarbons, halogenated aromatic hydrocarbons, aliphatic hydrocarbons, chlorinated alkanes, ethers, alcohols or water, alone or as a mixture. . 14. Method according to one of the preceding claims implemented at a temperature between 0 ° C and 180 ° C and at a pressure between atmospheric pressure and 10 MPa (100 bar).  15. Method according to one of the preceding claims, conducted in a closed system, in a semi-open system or in a continuous system, with one or more reaction stages.