FR2983475A1 - PROCESS FOR THE METATHESIS OF ALPHA LINEAR OLEFINS USING AN RUTHENIUM COMPLEX COMPRISING A DISSYMETRIC N-HETEROCYCLIC CARBENE - Google Patents

Abstract

The present invention describes a method of metathesis of alpha linear olefins, identical or different, to internal linear olefins, with excellent selectivity, using as catalyst a ruthenium complex having an asymmetric N-heterocyclic carbene for which one of the nitrogen atoms carries a cycloalkyl group having a carbon number greater than 3 and the other nitrogen atom bears an aryl group.

Description

FIELD OF THE INVENTION The present invention relates to the metathesis of alpha linear olefins, which is a catalytic conversion reaction of olefins, consisting in 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 'different from R "or homometathesis if R' = R" . R "10 Study of the Prior Art The metathesis reaction has become an important tool for the formation of carbon-carbon bonds and is used in the fields of petrochemistry, polymers, oleochemistry and Fine carbene complexes based on ruthenium have been described to catalyze this reaction (Chem Rev, 2010, 110, 1746-1787), WO 01/46096 discloses a process for converting C4-C10 olefins from a Fisher-Tropsch process to C6-C18 olefins using a homogenous ruthenium-type Grubbs (1st generation) catalyst of the formula RuCl 2 (PCy 3) 2 (CHPh) with improved selectivity over known heterogeneous catalysts of Those skilled in the art Ru complexes having a non-symmetric 5-membered NHC-type heterocyclic carbenic ligand have been described by Blechert (Organometallics, 2006, 25, 25-28). complex ca N-heterocyclic rbenic compounds according to the Anglo-Saxon terminology "N-heterocyclic carbenes". The complexes described in Blechert have been used to catalyze olefin cross metathesis, but they do not show any advantage over the symmetric NHC carbene bearing complexes previously described by Grubbs.

WO2011 / 056874 discloses a catalytic composition based on a Ru complex comprising a dissymmetrical NHC carbene for the production of alpha olefins by metathesis of triglycerides or 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 improving 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. OBJECT OF THE INVENTION An object of the invention is to provide a metathesis method using a catalytic system for producing linear internal olefins from linear alpha olefins, with both good conversions, a low ruthenium content and with 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 one of the nitrogen atoms bears a cycloalkyl group R7 having a carbon number greater than 3 and the other nitrogen atom bears an aryl group R8, R4 R5 R3, R6 Rs-NN-R7 X. IX, Ru = YL Formula I in which: X are the same or different and are anionic ligands, L is a donor ligand with 2 electrons, Y represents an alkylidene, vinylidene, allenylidene or indenylidene moiety, substituted or unsubstituted, Y optionally being able to form a ring with L, R3, R4, R5 and R6, which may be identical or different, are hydrogen, alkyl, cycloalkyl, aryl or arylalkyl groups, each of which may be substituted by alkyl, halide or alkoxy groups; oxy or with 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 R7 is therefore different from the ligand R8. For the purposes of the present invention, R7 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 (tricyclic biou) with a carbon number greater than 3, preferably between 4 and 18, such as for example the adamantyl or norbornyl groups. R8 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 cyclic rings can advantageously be condensed two by two or attached two by two by a bonds. For the purposes of the present invention, the substituents R3, R4, R5 and R6, which may be identical or different, are alkyl, cycloalkyl, aryl or arylalkyl groups, each of which may be substituted by alkyl, halide, alkoxy or optionally phenyl groups. 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. The term "alkoxy" substituent means 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 R3, R4, R5 and R6 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 advantageously chosen from methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl groups. By "cycloalkyl" is meant for R3, R4, R5 and R6 a monocyclic cyclic hydrocarbon group having preferably 3 to 10 carbon atoms, especially a cyclopentyl or cyclohexyl group, or a polycyclic (bicyclic or tricyclic) group having 4 to 10 carbon atoms. at 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 two by two by a bonds. By "arylalkyl", or "aralkyl" is meant for R3, R4, R5 and R6 a linear or branched hydrocarbon group carrying a monocyclic aromatic ring having 7 to 12 carbon atoms, the aliphatic chain comprising 1 or 2 atoms of carbon. A preferred arylalkyl or aralkyl group is benzyl. The ligands XX is an anionic ligand advantageously chosen from halides, sulphates, alkyl sulphates, aryl sulphates, alkyl sulphonates, aryl sulphonates, alkyl sulfinates, aryl sulfinates, acyls, carbonates, carboxylates, alcoholates and phenolates. , amides and pyrolides. 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 20 substituent groups, with the exception of the halides, can advantageously themselves be substituted or not, by one or more of the groups chosen from halides, alkyl groups having 1 to 6 carbon atoms, alcoholic groups having 1 to 6 carbon atoms, and aryl groups. Preferably, the ligands X are identical or different anionic ligands, chosen from halide ligands, benzoates, tosylates, mesylates, trifluoromethanesulfonates, pyrolides, CF3CO2 trifluoroacetates, CH3CO2 acetates, and alkoxide groups. such as CH3O, CH3CH2O, (CH3) 3CO, (CF3) 2 (CH3) CO, (CF3) (C1-13) 2CO, phenolates such as C6F50, C6H50.

Preferably, the anionic ligands X are chosen from halide ligands and very preferably the two ligands X are identical and are chlorides or bromides.

L L ligand 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, 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 '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 PR3, P (OR) 3, PH2R, PHRR1, PRR1R2 and P (OR) (OR1) (OR2) in which the groups R, R1 and R2 are all the same or different and are selected from alkyl, cycloalkyl, aryl and arylalkyl groups each having 1 to 20 carbon atoms and preferably 1 to 12 carbon atoms. Each of said groups R, R1 and R2 may 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 tricyclopentylphosphine, a di-alkyl or a di-cycloalkyl phosphine chosen from dicyclohexylphosphine, dicyclohexylphenylphosphine, di-tert-butylphosphine and di-tert-butylchlorophosphine or a triarylphosphine chosen 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: ## STR2 ## -NN-R7 R8-N N-R7 R8-NN-R7 R9 XIX, X, R9, Ru, Ru, RuI XX X, Ru PCy3 PPh3 PCy3 R4 R5 R3 R6 R4 R5 R4 R5 R8-NN-R7 R3 R6 R3-) k.-R6 XI R8-NN-R7 R8-NyN-R7: R-Phx1N) (CF3 XIX: L = C = C = C \ H: Ru = \ / PCy3 PCy3 0 X 1 Wherein X is selected from chloride and bromide ligands and R3, R4, R5, R6, R7 and R8 are defined as for formula I. R9 may be hydrogen or substituted or unsubstituted aryl. Preferably, R 9 is a substituted or unsubstituted phenyl group, very preferably the X ligands are identical and are chosen from chlorine or bromide ligands, L is a tricyclohexylphosphine and Y is an indenylidene group, substituted or unsubstituted. 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, hexene1, heptene-1, octene-1, nonene-1 or decene-1. Linear alpha olefins can be used alone or as a mixture. The charge may for example come from a Fischer-Tropsch process. Catalyst Implementation 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 metathesis process of the olefins according to the invention can 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 may 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 water. A preferred solvent is chlorobenzene. The combinations of these solvents may 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 of the olefins according to the invention is advantageously carried out under vigorous stirring, insofar as it allows a 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 may 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 the olefins according to the invention is advantageously carried out at a temperature of between 0 ° C. and 180 ° 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 from about five minutes to about 10 hours. The invention will be further elucidated in view 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: Method of metathesis of octene-1 with the catalyst A carrying a symmetrical NHC (not in accordance with the invention) The metathesis of octene-1 was carried out with a carbenic complex NHC symmetrical of the structure In Catalyst A In a reaction tube equipped 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 into the reaction tube. . 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, freshly distilled and filtered on basic alumina, and then degassed before the test, which corresponds to the time t = 0 of the reaction, are added. 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: ((mole initial octene-1 - mole final octene-1) / mole octene-1 start) * 100 The selectivity in tetradecene is calculated with the following formula: ((mole tetradecene * 2) / (mole octene-1 starting - mole octene-1 final)) * 100 The results after 4h 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) F-Mes-NKN-Mes I Ru_ PCy3 Catalyst B The metathesis reaction of octene-1 was performed as in Example 1 using Catalyst B instead of Catalyst A. The results after 4 hours of test are shown in the table below.

EXAMPLE 3 Process for metathesis of octene-1 with catalyst C carrying an asymmetric NHC (according to the invention) N Mes 7C1, I Ru Ph CIPCy3 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 Amount in Molar Temperature Conversion Selectivity of Ru by (° C) octene-1 homometathesis relative to olefin (%) (%) (ppm) Example 1: 50 50 79 95 Catalyst A 50 80 80 91 (non-compliant) Example 2: 50 50 Catalyst B 50 80 77 92 (not in conformity) Example 3: 50 50 80 99 Catalyst C 50 80 72 99 (according to the invention) It is observed that the process according to the invention makes it possible to obtain from octene-1 of tetradecene (C14) with a selectivity of 99%, higher than that obtained with the known catalysts. This excellent selectivity allows easier separation of the product and easy recycling of unreacted olefin. 10

Claims (15)

REVENDICATIONS1. 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 R7 having a carbon number greater than 3 and the other nitrogen atom carrying an aryl group R8, R4 R5 R6 R8-iv X, Ru = YX Formula I wherein: - X are the same or different and are ligands anionic, 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, - R3, R4, R5 and R6, which are 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 h groups; aliphatic, alkyl or alkoxy. 2. The process according to claim 1, wherein R7 is a monocyclic cycloalkyl group having a carbon number between 4 and 24, or polycyclic having a carbon number between 4 and 18. 3. Method according to one of the preceding claims wherein R8 is an aromatic mono- or polycyclic group having a carbon number between 6 and 20. 4. Method according to one of the preceding claims wherein R3, R4, R5 and R6 are identical or different, and are selected from - a linear or branched alkyl group having 1 to 15 carbon atoms, a monocyclic cycloalkyl group having 3 to 10 carbon atoms, or polycyclic having 4 to 18 carbon atoms, - an aromatic mono- or bicyclic group having 6 to 20 carbon atoms, - a linear or branched arylalkyl group carrying an aromatic ring monocyclic having 7 to 12 carbon atoms, the aliphatic chain comprising 1 or 2 carbon atoms. 5. Process according to one of the preceding claims, in which X is an anionic ligand chosen from halides, sulphates, alkyl sulphates, aryl sulphates, alkyl sulphonates, aryl sulphonates, alkyl sulfinates, aryl sulfinates, acyls, carbonates, 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, groups aryl having 5 to 24 carbon atoms and the halides, said substituent groups, with the exception of the halides, being themselves substituted or not by one or more of the groups selected from halides, the alkyl groups having from 1 to 6 carbon atoms, alkoxide groups having 1 to 6 carbon atoms, and aryl groups. 6. Process according to the preceding claim, in which X is chosen from halide ligands, benzoates, tosylates, mesylates, trifluoromethanesulfonates, pyrolides, CF3CO2 trifluoroacetate groups, CH3CO2 acetates, alcoholates and phenolates. 7. Method according to one of the preceding claims wherein L is a phosphorus ligand of formula PR'3 wherein P is a phosphorus atom and R 'is selected from R and (OR) groups 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 comprising 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 a hydrogen or a halide, and in the case where R 'is a group R, at at least one of the R's 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. 15 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 selected from linear alpha-olefins having from 3 to 20 carbon atoms, alone or in admixture. 11. Process according to the preceding claim wherein the olefin is selected from pentene-1, hexene-1, heptene-1, octene-1, nonene-1 or decene-1. 25 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 10000 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 in mixed. 14.Procédé according to one of the preceding claims carried out at a temperature between 0 ° C and 180 ° C and at a pressure between atmospheric pressure and 10 MPa (100 bar). 15.Procédé according to one of the preceding claims conducts closed system, semi-open system or continuous system, with one or more reaction stages.