WO2018147793A1

WO2018147793A1 - Carbonylation process and ligand composition comprising a bidentate phosphite ligand and a tertiary phosphine anti-oxidant

Info

Publication number: WO2018147793A1
Application number: PCT/SE2018/050120
Authority: WO
Inventors: Ian MUNSLOW; Matias KANGAS
Original assignee: Perstorp AB
Current assignee: Perstorp AB
Priority date: 2017-02-09
Filing date: 2018-02-09
Publication date: 2018-08-16
Anticipated expiration: 2019-08-09
Also published as: CN110267936A; SE1730036A1

Abstract

Disclosed is a carbonylation process comprising subjecting at least one olefin to hydroformylation in presence of a syngas, comprising carbon monoxide and hydrogen, at least one Group VIII transition metal catalyst or catalyst precursor and at least one phosphite ligand of Formula (I) and at least one anti-oxidant selected from the group consisting of tertiary phosphines, such as triarylphosphines, dicycloalkylarylphosphines and/or cycloalkyldiarylphosphines. In a further aspect the present invention refers to a ligand mixture comprising at least one phosphite ligand of Formula (I) and at least one said anti-oxidant.

Description

Carbonylation Process and Ligand Composition Comprising a Bidentate Phosphite Ligand and a Tertiary Phosphine Anti-oxidant

The present invention refers to a carbonylation, such as a hydroformylation, process in presence of a syngas comprising carbon monoxide and hydrogen, at least one Group VIII transition metal catalyst or catalyst precursor and at least one ligand mixture comprising at least one phosphite ligand of Formula (I) and at least one anti-oxidant selected among tertiary phosphines. In a further aspect, the present invention refers to a said ligand mixture and its use in carbonylation processes.

Industrial processes, such as carbonylation reactions including hydroformylations and cyclohydrocarbonylations of functionalised and unfunctionalised alkenes, alkadienes, and alkynes for production of commodity chemicals and speciality chemicals often use as catalysts Group VIII transition metals complexed with one or more ligands, such as organophosphines and organophosphites. Carbonylation processes directed to production of oxygenated products, in the presence of catalysts, in general involve the reaction of an organic compound with carbon monoxide and optionally at least one other reactant and are well known in the art. Said processes include the carbonylation of organic compounds, such as olefins, acetylenes, alcohols and activated chlorides, with carbon monoxide alone or with carbon monoxide and either hydrogen, alcohol, amine, water or a reducing agent, as well as ring closure reactions of functional unsaturated compounds, for instance unsaturated amides, with carbon monoxide. A major type of known carbonylation reactions is hydroformylations of olefinic compounds with carbon monoxide and hydrogen to produce oxygenated products, such as aldehydes, using Group VIII transition metals complexed with phosphorus ligands, wherein the phosphorus ligands typically are organophosphines and/or organophosphites.

Hydroformylation is the general term applied to the reaction of an olefinic substrate with carbon monoxide and hydrogen and/or a reducing agent to form aldehydes having one carbon atom more than the original olefinic reactant as illustrated by Scheme 1 below.

CHO wherein R is a hydrocarbyl residue optionally comprising functional groups, such as carboxyl, hydroxyl and/or ester groups. One of the most important industrial applications for hydroformylation processes is the so called oxo process, that is hydroformylation of olefins in the presence of transition metal catalyst complexes. Yielded aldehydes can for instance be hydrogenated to give so called oxo alcohols and long-chain products can be converted into sulphonates and used as detergents. The oxo process was discovered in 1938 by Roelen and coworkers of Ruhr Chemie. The first catalysts, and still used on a large scale, were cobalt carbonyl complexes formed from [HCo(CO)₄]. This process is carried out at temperatures of 120-175°C and pressures of several hundred atm. The high pressures are required to maintain the cobalt in the form of a soluble metal carbonyl complex. Use of cobalt complexes with organophosphine and/or organophosphite ligands led to processes with improved selectivities. A significant advance in hydroformylation technology was made with the discovery that phosphine and phosphite complexes of rhodium, similar to those used in the Wilkinson hydrogenation, have catalytic activities several times higher than cobalt cabonyl complexes. Hydroformylation and the oxo process are further disclosed and discussed in for instance Kirk-Othmer Encyclopedia of Chemical Technology, 4^th ed. vol. 17, chapter "Oxo Process" and in Applied Homogeneous Catalysis with Organometallic Compounds - A Comprehensive Handbook in Two Volumes, chapter 2.1.1. pages 29-102, " Hydroformulation (Oxo Synthesis, Roelen Reaction)" .

It is well known that the selection of phosphorus ligands employed in said catalysed carbonylation processes effects the success of a given process. It is also evidenced that the selection of a particular phosphorus ligand to be used in any such transition metal catalysed carbonylation process mainly depends on the desired end result. It is, furthermore, well known that not all phosphorus ligands provide identical results with regard to all factors under all conditions and the best overall processing efficiency may require a compromise selection among numerous factors involved. For example, in hydroformylation such factors as product selectivity, catalyst reactivity as well as catalyst and ligand stability are often of major concern in the selection of a phosphorus ligand to be employed. Moreover, such a selection may also depend on for instance the olefinic starting material as all olefins do not have the same degree of reactivity under all conditions. Internal olefins and sterically hindered oc-olefins, such as isobutylene, are in general much less reactive than sterically unhindered oc-olefins. Organophosphite ligands of Formula (I)

Formula, (i)

wherein -R , -R , -R , -R , R , R , R and R individually is hydrogen or a linear or branched alkyl group and -Ar is a substituted or unsubstituted aryl group, such as a group of Formula (II) or (III)

Fsnm * (Ill)

are known in the art to be excellent ligands in carbonylation, such as hydroformylation, reactions catalysed by Group VIII transition metals.

It has, however, been observed that these organophosphite ligands tend to readily oxidize on addition to a reaction mixture and/or during storage, with between roughly 1/4 and 1/3 or even more of these ligands oxidized, thus reducing the active amount of said ligand and thus implying for instance reduced catalytic effect, reduced processing efficiency, altered selectivity and/or yield. Said oxidation also implies addition of larger than optimum amounts of ligand to compensate for oxidized material, thus implying unnecessary high costs. There have been several attempts in the prior art trying to solve this organophosphite ligand oxidation problem by adding a second phosphorous-based compound. For instance, W 02010117391 discloses a hydroformylation process conducted in the presence of a mixture of an organopolyphosphite ligand and an organomonophosphine ligand forming a transition metal ligand complex hydroformylation catalyst. The molar ratio of both the organomonophosphine and the organopolyphosphite to the metal being at least 1. RU2584952 discloses a hydride-carbonyl polyphosphite complex of rhodium with mixed organophosphorus ligands. The complex having the general formula HRh(CO)(A)(B), where A is a polyphosphite ligand and B is an organophosphine or an organophosphinite. W09819990 is mainly about avoiding catalyst deactivation by adding some acid to the hydroformylation process, but it also teaches that in order to further improve the stability of the catalyst system it is preferred to add some organophosphorus compound, e.g. monodentate phosphine.

In all of these references the added phosphine compound is coordinating to the rhodium phosphite ligand complex. A rhodium ligand complex comprising both phosphite and phosphine however has a much poorer product selectivity than a rhodium ligand complex comprising only phosphite. It is therefore desirable to find a way to avoid the organophosphite ligand oxidation without decreasing the product selectivity.

It has now quite unexpectedly been found that oxidation of an organophosphite ligand of said Formula (I) can be avoided or substantially reduced, to levels below 1% on charging and less than 2% during a typical storage time of 5 days or less, by addition of sub stoichiometric amounts of one or more less efficient and/or cheaper tertiary phosphines as anti-oxidants without detrimental effect on the carbonylation process, the resulting end product and/or the catalytic effect of a catalyst complex resulting from at least one Group VIII transition metal and at least one ligand of Formula (I). The present invention accordingly refers to a carbonylation process, such as hydroformylation, catalysed by one or more Group VIII transition metal(s) wherein said Group VIII transition metal is complexed with at least one phosphite ligand of Formula (I) and in the presence of an anti-oxidant selected from the group consisting of tertiary phosphines, such as triarylphosphines, dicycloalkylarylphosphines and/or cycloalkyldiarylphosphines. Especially preferred phosphine anti-oxidants include, in embodiments of the present invention, phenyldi(o-, m- or /?-tolyl)phosphines, diphenyl(o-, m- or /?-tolyl)phosphines, tri(o-, m- or /?-tolyl)phosphines, phenyldibenyzylphosphines, diphenylbenzylphosphines, tribenzylphosphines, phenyldinaphthyl- phosphines, diphenylnaphthylphosphines, trinaphthylphosphines, dicyclohexylbenzylphosphines and/or cyclohexyldibenzylphosphines.

Said Formula (I) ligand is suitably used in an amount of 0.5-15, such as 1-10 or 1-5, % by weight calculated on total reaction mixture and said anti-oxidant in an amount of 0.01-5, such as 0.05-2, % likewise by weight calculated on total hydroformylation mixture, corresponding to a Group VIII transition metakphosphite ligand of Formula (I): anti-oxidant molar ratio of 1:2:0.3-0.9.

The presence of a monophosphine protects the phosphite ligand from oxidation due to air ingress. One purpose of the present invention is to ensure ligand stability during storage. However in air- free process environments, like in most hydroformylation reactors, the presence of phosphine is not needed, or in only very small amounts. On the contrary there is a risk that the presence of phosphine has a negative effect on the product selectivity since the phosphine compete with the phosphite ligand on coordinating to the Group VIII transition metal, usually rhodium.

One embodiment of the present invention refers to catalyst preparation. Due to the oxygen scavenging property of the phosphine it is possible to prepare the catalyst solution without the phosphite ligand being oxidized due to air ingress. Catalyst preparation in air-free conditions are more expensive. The monophosphine is added in sub stoichiometric amounts in order to avoid complexation and when the catalyst solution is added to the hydroformylation process there is almost no phosphine left, which is beneficial for the product selectivity.

In preferred embodiments of the present invention, -Ar is a group of Formula. (II) and -R , -R , - R⁶ and -R⁸ are n-butyl, z^'so-butyl or tert-buty\. In a further preferred embodiment, -R⁴ and -R⁵ are methyl and in yet a further preferred embodiments said group of Formula (II) or (III) is suitably substituted by at least one linear or branched Ci-C₆ alkyl group.

The process of the present invention is advantageously and preferably a hydroformylation of at least one C2-C12 olefin, such as ethylene, a propene, a butene, including 1-butene and cis- or trans- 2-butene, a pentene and/or a hexene, in presence of at least one Group VIII transition metal, such as ruthenium, palladium, osmium, iridium, platinum and rhodium, catalyst or catalyst precursor.

Said Group VIII transition metal is suitably and advantageously present in said process in an amount of 20-1000, such as 50-550, ppm by weight of obtained hydroformylation mixture. Furthermore, said Group VIII transition metal catalyst is suitably and preferably charged in form of a precursor selected from the group consisting of a hydride, a halide, anitrate, a carbonyl compound, an acetate and a dicarbonyl-acetylacetonate. In especially preferred embodiments of the process of the present invention, said Group VIII transition metal is rhodium and said precursor is selected from rhodium(III)nitrate, rhodium(III)acetate, rhodium(I)acetate, acetyl- acetonatedicarbonyl rhodium(I), di(rhodium)tetracarbonyl dichloride, dodecancarbonyl- tetrarhodium and/or hexadecane carbonylhexarhodium.

In a further aspect, the present invention refers to a ligand mixture comprising at least one phosphite ligand of Formula I and at least one anti-oxidant selected from the group consisting of tertiary phosphines, such as triarylphosphines, dicycloalkylarylphosphines and/or cycloalkyldiarylphosphines. Especially preferred embodiments of said anti-oxidant phosphine ligands include, but is not limited to, phenyldi(o-, m- or /?-tolyl)phosphines, diphenyl(o-, m- or p- tolyl)phosphines, tri(o-, m- or /?-tolyl)phosphines, phenyldibenyzylphosphines, diphenylbenzyl- phosphines, tribenzylphosphines, phenyldinaphthylphosphines, diphenylnaphthylphosphines, trinaphthylphosphines, dicyclohexylbenzylphosphines and/or cyclohexyldibenzylphosphines.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilise the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative and not limitative in any way whatsoever. Given in the following are experimental set-up and data on oxidation of an embodiment of a phosphite ligand of Formula (I) and on hydroformylation using ligand compositions according to embodiments of the present invention. The result of oxidation analyses are given in attached Table 1 and the hydroformylation reactants and result are given in attached Table 2. Experimental - Oxidation

Diphenyl(p-tolyl)phosphine (DPTP) was, as an anti-oxidant, mixed with a phosphite ligand of Formula (I) having CAS no. 198979-98-5, hereinafter designated A4N3, and added to sample vials containing valeric aldehyde. The amounts of anti-oxidant investigated were 0% (blank sample), 0.25% and 2% by weight calculated on the total mixture and A4N3 amounts added were 2% by weight calculated on total mixture. The test was repeated using tri(p-tolyl)phosphine (TPTP) and tri(o-tolyl)phosphine (TOTP) as anti-oxidants. All experiments were carried out under N₂ atmosphere in order to show the oxidizing effect of air dissolved in the valeric aldehyde solution. The amount of mono-oxidised and di-oxidised A4N3 were analysed directly after sample preparation (initial) and after an additional 5 days of storage at room temperature. The result, average of all tested anti-oxidants, is presented in table 1 and evidences a substantial reduction, even at the lowest addition level of anti-oxidant.

Table 1

Initial = immediately after addition of ligands to the olefin.

* Percentage of initial A4N3 content. Experimental - Hydroformylation

Experiments were carried out in a 300 ml Parr reactor using 300 g of a catalyst solution and 80 g of an olefin. The catalyst solutions consisted of methanol (3% by weight on reaction mixture), toluene (>95% by weight on reaction mixture), rhodium(III) acetate as Rh-source at a Rh addition of 500 ppm of reaction mixture. Additionally the ligand A4N3 was added at 1.05% by weight on reaction mixture and diphenyl(p-tolyl)phosphine (DPTP), tri(p-tolyl)phosphine (TPTP) or tri(o- tolyl)phosphine (TOTP) were used as anti-oxidants added at 0.07% by weight on reaction mixture, corresponding to a Rh:A4N3: anti-oxidant molar ratio of 1:2:0.4-1.3. Hydroformylation of butene was carried out at 95 °C and 14 bar pressure of a syngas, comprising CO and H₂, for 5-7 hrs. The reaction mixture was pumped via a piston pump through a React- IR, IR scans were recorded at 30 second intervals and samples were taken at regular intervals for GC/HPLC analysis. Upon completion, the reactor was cooled, gasses vented to a dump vessel, the reactor was purged several times with N₂ and the reaction mixture was then removed via the sample point. The products regioselectivity were analysed showing that addition of the anti-oxidant in sub stoichiometric amounts does not negatively affect the selectivity, however when the anti-oxidant is added in stoichiometric excess a decreased selectivity is observed. Obtained regioselectivities are given in Table 2 as the ratio between linear and branched aldehydes.

Table 2

Experiment Main ligand Anti-oxidant Rh : A4N3 : anti-oxidant N:I ratio

1 A4N3 1:2:0 37

2 A4N3 DPTP 1:2:0.4 37

3 A4N3 TPTP 1:2:0.4 36

4 A4N3 TOTP 1:2:0.4 38

5 A4N3 TOTP 1:2: 1.3 31

Claims

1. A carbonylation process comprising subjecting at least one olefin to hydroformylation in presence of a syngas, comprising carbon monoxide and hydrogen, at least one Group VIII transition metal catalyst or catalyst precursor and at least one phosphite ligand of Formula (I)

Formula (1)

wherein -R , -R , -R , -R , R , R , R and R individually are hydrogen or a Ci-C₆ linear or branched alkyl group and -Ar is a substituted or unsubstituted group of Formula (II) or (III)

Fotiss!a il)

in an amount of 0.5-15, such as 1-lO or 1-5, % by weight calculated on total hydroformylation mixture, wherein oxidation of said at least one ligand of Formula (I) is avoided or substantially reduced by addition of at least one anti-oxidant selected from the group consisting of tertiary phosphines and wherein said anti-oxidant is added in an amount of 0.01- 5, such as 0.05-2, % by weight calculated on total hydroformylation mixture.

2. The process according to Claim 1, wherein said group of Formula (II) or (III) is substituted by at least one linear or branched Ci-C₆ alkyl group.

3. The process according to any of the Claims 1-2, wherein -Ar is a group of Formula. (II) and wherein -R , -R , -R and -R are n-butyl, z^'so-butyl or preferably tert-butyl.

4. The process according to any of the Claims 1-3, wherein R⁴ and R⁵ are methyl.

5. The process according to any of the Claims 1-4, wherein said at least one anti-oxidant is a triarylphosphine, a dicycloalkylarylphosphine and/or a cycloalkyldiarylphosphine.

6. The process according to any of the Claims 1-5, wherein said at least one anti-oxidant is a phenyldi(o-, m- or /?-tolyl)phosphine, a diphenyl(o-, m- or /?-tolyl)phosphine, a tri(o-, m- or /?-tolyl)phosphine, a phenyldibenyzylphosphine, a diphenylbenzylphosphine, a tribenzyl- phosphine, a phenyldinaphthylphosphine, a diphenylnaphthylphosphine, a trinaphthyl- phosphine, a dicyclohexylbenzylphosphine and/or a cyclohexyldibenzyl- phosphine.

7. The process according to any of the Claims 1-6, wherein said at least one olefin is a C2-C12 olefin.

8. The process according to any of the Claims 1-7, wherein said at least one olefin is ethylene, a propene, a butene, a pentene or a hexene.

9. The process according to any of the Claims 1-8, wherein said at least one olefin is 1-butene and/or cis- or iran5-2-butene.

10. The process according to any of the Claims 1-9, wherein said at least one Group VIII transition metal catalyst is charged in form of a precursor selected from the group consisting of a hydride, a halide, anitrate, a carbonyl compound, an acetate and a dicarbonyl- acetylacetonate.

11. The process according to any of the Claims 1-10, wherein said at least one Group VIII transition metal is rhodium.

12. The process according to Claims 10 or 11, wherein said at least one Group VIII transition metal catalyst is rhodium and said precursor is rhodium(III)nitrate, rhodium(III)acetate, rhodium(I)acetate, acetylacetonatedicarbonyl rhodium(I), di(rhodium)tetracarbonyl dichloride, dodecancarbonyltetrarhodium or hexadecane carbonylhexarhodium.

13. The process according to any of the Claims 1-12, wherein said at least one Group VIII transition metal is present in an amount of 20-1000, such as 50-550, ppm by weight of obtained hydroformylation mixture.

14. The process according to Claim 1, wherein said Group VIII transition metal, phosphite ligand of Formula (I) and anti-oxidant are present in a molar ratio of 1:2:0.3-0.9.

15. The process according to any of the Claims 1-14, wherein said oxidation is less than 2% by weight of charged ligand of Formula (I) during 5 days or less of storage.

16. The process according to any of the Claims 1-15, wherein a catalyst solution comprising at least one of said Group VIII transition metal catalyst or catalyst precursor, at least one of said phosphite ligand of Formula (I) and at least one of said anti-oxidants is prepared without any substantially oxidation of the phosphite ligand due to air ingress.

17. The process according to any of the Claims 1-16, wherein said anti-oxidant is added in sub stoichiometric amounts in order to avoid complexation with said Group VIII transition metal.

18. A ligand mixture for use in reactions catalysed by at least one Group VIII transition metal catalyst or catalyst precursor, said ligand mixture comprising at least one phosphite ligand of Formula (I) Formula (1)

in an amount of 0.5-15, such as 1-10 or 1-5, % by weight calculated on total reaction mixture and at least one anti-oxidant selected from the group consisting of tertiary phosphines in an amount of 0.01-5, such as 0.05-2, % by weight calculated on total reaction mixture.

The ligand mixture according to Claim 18, wherein -Ar is a group of Formula. (II) and wherein -R , -R , -R and -R are n-butyl, z^'so-butyl or preferably tert-butyl.

The ligand mixture according to Claim 18 or 19, wherein -R⁴ and -R⁵ are methyl.

21. The ligand mixture according to any of the Claims 18-20, wherein said group of Formula (II) or (III) is substituted by at least one linear or branched Ci-C₆ alkyl group.

22. The ligand mixture according to any of the Claims 18-21, wherein said at least one antioxidant is a triarylphosphine, a dicycloalkylarylphosphine and/or a cycloalkyldiaryl- phosphine.

23. The ligand mixture according to any of the Claims 18- '22, wherein said at least one antioxidant is a phenyldi(o-, m- or /?-tolyl)phosphine, a diphenyl(o-, m- or /?-tolyl)phosphine, a tri(o-, m- or /?-tolyl)phosphine, a phenyldibenyzylphosphine, a diphenylbenzylphosphine, a tribenzylphosphine, a phenyldinaphthylphosphine, a diphenylnaphthylphosphine, a trinaphthylphosphine, a dicyclohexylbenzylphosphine and/or a cyclohexyldibenzyl- phosphine.

24. The ligand mixture according to any of the Claims 18-23, wherein said reaction is a hydroformylation of at least one C2-C12 olefin.

25. The ligand mixture according to Claim 24, wherein said at least one olefin is ethylene, a propene, a butene, a pentene and/or a hexene.

26. The ligand mixture according to Claim 24 or 25, wherein said at least one olefin is 1-butene and/or cis- or irafts-2-butene.

27. The ligand mixture according to any of the Claims 18-26, wherein said at least one Group VIII transition metal is rhodium.