Catalyst for the hydroformylation of olefins, and use thereof

Abstract

A catalyst for the hydroformylation of at least one olefin, having a ligand fo the general formula (1) R.sup.1, R.sup.2, R.sup.3 selected from the group including substituted and non-substituted alkyl, substituted and non-substituted aryl, substituted and non-substituted alkenyl, substituted and non-substituted alkinyl, substituted and non-substituted cycloalkyl, and substituted and non-substituted heterocycles, wherein R.sup.1, R.sup.2 and R.sup.3 can each be the same or different, L is selected from a group having a sandwich complex, an oxygen group, substituted and non-substituted alkylene or heterocycles, and substituted aryl or heteroaryl; and aryl and heteroaryl is each substituted with groups which contain at least two heteroatoms and are coupled to the Si via the at least two heteroatoms of the substituents, n=1-10, preferably 1-5, particularly preferably 1, 2, or 3; and the ligand is coupled to the metal M from the group VIIIb of the periodic table of elements via the Si group.

Claims

1. A catalyst for the hydroformylation of at least one olefin comprising, a ligand of general formula (I) ##STR00009## R1, R2 and R3 are selected from the group comprising substituted and unsubstituted alkyl, substituted and unsubstituted aryl, substituted and unsubstituted alkenyl, substituted and unsubstituted alkinyl, substituted and unsubstituted cycloalkyl, substituted and unsubstituted heterocycles, wherein R1, R2 and R3 can each be the same or different, L is selected from a group comprising a sandwich complex, an oxygen group, substituted and unsubstituted alkylene or heteroalkylene, substituted aryl or heteroaryl, wherein aryl and heteroaryl are each substituted with groups comprising at least two heteroatoms and are coupled to the Si via the at least two heteroatoms of the substituents, n=1-10; wherein the ligand is coupled to the metal M from group VIIIb of the periodic table of elements via the Si group, wherein M is Rh; wherein ligand and metal form a complex of general formula (II) ##STR00010## wherein Z is a non-metallic element of group Va of the periodic table of elements or a CO ligand, R4, R5, and R6 are selected from the group comprising substituted and unsubstituted alkyl, substituted and unsubstituted aryl, substituted and unsubstituted alkenyl, substituted and unsubstituted alkinyl, substituted and unsubstituted cycloalkyl, substituted and unsubstituted heterocycles, wherein R4, R5, and R6 can each be the same or different, and m=0-3.

2. The catalyst as claimed in claim 1, wherein Z is phosphorus or nitrogen.

3. The catalyst as claimed in claim 1, wherein R4, R5, and R6 are selected from the group comprising substituted and unsubstituted C1-C12 alkyl, substituted and unsubstituted phenyl, substituted and unsubstituted C5-C6 heteroaryl, substituted and unsubstituted naphthyl, substituted and unsubstituted C3-C7 cycloalkyl, substituted and unsubstituted C7-C18 alkylphenyl, substituted and unsubstituted C5-C7 cycloalkenyl, and substituted and unsubstituted C2-C7 heteroalkylene.

4. The catalyst as claimed in claim 1, wherein R4, R5, R6 are selected from the group comprising substituted and unsubstituted phenyl.

5. The catalyst as claimed in claim 1, wherein m=3.

6. A method for the hydroformylation of olefins in the presence of a catalyst comprising a ligand of general formula (I) ##STR00011## wherein R1, R2 and R3 are selected from the group comprising substituted and unsubstituted alkyl, substituted and unsubstituted aryl, substituted and unsubstituted alkenyl, substituted and unsubstituted alkinyl, substituted and unsubstituted cycloalkyl, substituted and unsubstituted heterocycles, wherein R1, R2 and R3 can each be the same or different, L is selected from a group comprising a sandwich complex, an oxygen group, substituted and unsubstituted alkylene or heteroalkylene, substituted aryl or heteroaryl, wherein aryl and heteroaryl are each substituted with groups comprising at least two heteroatoms and are coupled to the Si via the at least two heteroatoms of the substituents, n=1-10, preferably 1-5, particularly preferably 1, 2, or 3; and wherein the ligand is coupled to the metal M from group VIIIb of the periodic table of elements via the Si group, comprising the following steps: preparation of a reaction mixture of at least one NiHs ligand and at least one metal precursor in a suitable solvent and addition of at least one substrate for the hydroformylation in a suitable reactor, under an inert gas atmosphere; addition of synthesis gas of carbon monoxide and hydrogen to the reaction mixture in the reactor; and carrying out the hydroformylation reaction at a temperature of between 50 and 100 C. and a pressure of between 30 and 50 bar.

7. The method as claimed in claim 6, wherein the catalyst is formed from the ligand and a precursor complex comprising the metal in situ in the reaction mixture.

8. The method as claimed in claim 6, wherein M is Co or Rh.

9. The method for hydroformylation of olefins as claimed in claim 6 the hydroformylation of styrene and C3-C15 olefins.

10. A method as claimed in claim 6 for the hydroformylation of styrene and 1-octene or 1-dodecene.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is explained in the following by means of several examples with reference to the figures.

(2) FIG. 1 shows a schematic illustration of the catalysis cycle of rhodium-catalyzed hydroformylation.

DETAILED DESCRIPTION

Example 1: Production of a First NHSi Ligand (1)

(3) ##STR00006##

(4) All of the experiments were carried out using standard Schlenk techniques with dry nitrogen as an inert gas. 1.6 M n-butyllithium (4.23 mL, 6.77 mmol) was added at 0 C. to a solution of hexane (10 mL) with ferrocene (600 mg, 3.23 mmol) and TMEDA (937 mg, 8.06 mmol). The reaction solution was stirred for 4 hours at 50 C. The reaction solution was then cooled to 78 C. A solution of the chlorosilylene (1.9 g, 6.45 mmol) in toluene (30 mL) was added dropwise to this for 5 min. The mixture was stirred overnight at room temperature, after which all of the volatile components were removed under a vacuum, and the residue was extracted with pentane. The dark-red crystals of (1) were stored in pentane at 0 C.

(5) .sup.1H-NMR (400.13 MHz, C.sub.6D.sub.6, 298K, ppm): =1.16 (s, 36H, NC(CH.sub.3).sub.3), 4.51 (t, .sup.3J (H,H)=1.5 Hz, 4H, FeCH), 4.72 (t, .sup.3J (H,H)=1.5 Hz, 4H, FeCH), 6.92-7.07 (m, 10H, arom. H); .sup.13C{.sup.1H} NMR (100.61 MHz, C.sub.6D.sub.6, 298K, ppm) =31.8 (NC(CH.sub.3).sub.3), 53.0 (NC(CH.sub.3).sub.3), 70.9 (FeCH), 72.7 (FeCH), 84.6 (SiC), 128.9, 129.4, 130.5, 134.9 (arom. C), 160.4 (NCN); .sup.29Si {.sup.1H} NMR (79.49 MHz, C.sub.6D.sub.6, 298K, ppm) =43.3;

(6) Characterization of the corresponding rhodium complex HRh (CO) (PPh.sub.3):

(7) ##STR00007##

(8) The rhodium precursor tris(triphenylphosphine)hydridocarbonyl-rhodium (I) HRh(CO) (PPh.sub.3).sub.3 and the NHSi ligand (1) were dissolved in an equimolar ratio in 0.5 ml of C.sub.6D.sub.6. An orange coloration was immediately observed. NMR results confirm the formation of the rhodium complex HRh(CO) (PPh.sub.3) (1).

(9) .sup.2H-NMR (200 MHz, THF-d.sub.8, 298 K, ppm): =9.43 (ps t: 1H, .sup.1J (H,Rh) and .sup.2J (H,P)=11.4 Hz) (P coupling visible), 0.87 (s, 18H, 2H-.sup.tBu-N), 1.29 (s, 18H, 2H-.sup.tBu-N), 4.15 (m, 8H, 4H-ferrocenes), 7.03-7.70 (m, 55H, H-PPh.sub.3+m, 10H, H-Ph). .sup.31P-NMR (81 MHz, THF, 298 K, ppm): =5.4 (s, P-PPh.sub.3) (free ligand), 44.7 (d, .sup.1J (P,Rh)=98.7 Hz).

(10) On addition of an excess of the NHSi ligand, the rhodium complex HRh(CO) (PPh.sub.3) was also formed, wherein excess ligand was not reacted.

Example 2: Production of a Second NHSi Ligand (2)

(11) ##STR00008##

(12) .sup.1H-NMR (400.13 MHz, C.sub.6D.sub.6, 298 K, ppm): symmetric conformer: =1.16 (s, 36H, NC(CH.sub.3).sub.3), 1.63 (t, .sup.3J (H,H)=6.9 Hz, 6H, NCH.sub.2CH.sub.3), 3.77 (q, .sup.3J (H,H)=6.9 Hz, 4H, NCH.sub.2CH.sub.3), 6.87-7.09 (m, 10H, arom. CH), 7.34-7.50 (m, 3H, arom. CH py.). Asymmetric conformer: =1.14 (s, 36H, NC(CH.sub.3).sub.3), 1.55 and 1.68 (t, .sup.3J (H,H)=6.9 Hz, 6H, NCH.sub.2CH.sub.3), 3.71 and 4.62 (q, .sup.3J (H,H)=6.9 Hz, 4H, NCH.sub.2CH.sub.3), .sup.13C{.sup.1H}-NMR (100.61 MHz, C.sub.6D.sub.6, 298 K, ppm): symmetric conformer: =16.9 (NCH.sub.2CH.sub.3), 31.6 (NC(CH.sub.3).sub.3) 31.9 (NCH.sub.2CH.sub.3), 52.9 (NC(CH.sub.3).sub.3), 101.8 (3.5-C.sub.arom. py), 127.6 (C.sub.arom), 128.5 (C.sub.arom), 129.3 (C.sub.arom), 129.3 (C.sub.arom), 129.4 (C.sub.arom), 130.0 (C.sub.arom), 130.5 (C.sub.arom), 130.5 (C.sub.arom), 134.7 (C.sub.arom quaternary Ph), 136.9 (4-C.sub.arom py), 161.2 (2,6-C.sub.arom py), 161.4 (NCN). Asymmetric conformer: =18.0 and 16.0 (NCH.sub.2CH.sub.3), 31.4 and 31.5 (NC(CH.sub.3).sub.3), 36.8 and 43.9 (NCH.sub.2CH.sub.3), 53.3 (NC(CH.sub.3).sub.3), 103.0 and 103.9 (3,5-C.sub.arom. py), 134.0 and 134.5 (C.sub.arom quaternary Ph), 136.4 (4-C.sub.arom py). .sup.29Si{.sup.1H}-NMR (79.49 MHz, C.sub.6D.sub.6, 298 K, ppm): symmetric conformer: =14.9. Asymmetric conformer: =13.8 and 17.1.

Example 3: Hydroformylation

(13) Preparation of Reaction Mixture:

(14) The rhodium precursor HRh(CO) (PPh.sub.3).sub.3 (0.01 mmol, 9.188 mg, 1 eq.) and the NHSi ligand (1) (3 eq.) were first placed in a 100 ml Schlenk flask and dissolved in freshly distilled toluene (0.434 mol, 40.0 g). Freshly distilled styrene (0.038 mol, 4.0 g, 3,800 eq.) was then added.

(15) Experimental Procedure for Hydroformylation of Styrene:

(16) Hydroformylation was carried out in a 100 ml stainless steel autoclave. Before adding the reaction mixture, the reactor was heated at 110 C. for one hour and then evacuated 3 in each case and flushed with nitrogen. After cooling to reaction temperature, the reaction mixture was injected into the reactor with a syringe under a nitrogen counterflow. After this, a reaction pressure of 30 bar synthesis gas (1:1 hydrogen and carbon monoxide) was applied in the reactor with a stirring rate of 200 rpm, and after the reaction pressure was reached, the stirring rate was increased to 1200 rpm. In order to achieve isobaric reaction conditions, converted synthesis gas was added by means of a mass flow controller. Samples were diluted with acetone and analyzed by gas chromatography.

(17) FIG. 1 illustrates a catalytic cycle of a rhodium catalyst with a bidentate ligand, beginning with the trigonal-bipyramidal hydride species 6, which is produced in situ according to the above reaction equation. The formation of active complex 7 is initiated by the loss of a triphenylphosphine ligand. coordination of the alkene on the unsaturated rhodium complex 7 leads to the formation of complex 8, after which migration of the hydride leads to the corresponding rhodium-alkyl complex 9. After coordination of an additional CO molecule with the formation of complex 10, CO is introduced into the rhodium-alkyl bond, forming the rhodium-acyl complex 11. By addition of hydrogen, which leads to the formation of complex 12, the aldehyde 12 is separated, and the active rhodium-hydride complex 7 is regenerated.

(18) In order to assess catalytic activity with the bidentate ligand according to the invention (indicated by (1) in the table), hydroformylation of styrene was investigated by comparison of XantPhos, a commonly-used bidentate phosphine ligand. In this case, turnover frequency (TOF), which describes the number of catalytic cycles of the catalyst per unit time, was used as a characteristic parameter. The results for various temperatures are shown in Table 1.

(19) TABLE-US-00001 TABLE 1 TOF values for the hydroformylation of styrene with bidentate ligands at various temperatures. Reaction conditions: 40 g toluene, 4 g styrene, n.sub.Rh 0.01 mmol, n.sub.ligand = 3 eq, p = 30 bar, rpm = 1200. TOF determined after 60 min at 50 C., after 30 min at 80 C., and after 10 min at 100 C. Ligand Temperature T [ C.] TOF.sup.a [1/h] (1) 50 83 XantPhos 50 32 (1) 80 2621 XantPhos 80 646 (1) 100 9075 XantPhos 100 3007

(20) As can be seen from Table 1, the TOF at all of the temperatures in use of the bidentate NHSi ligand according to the invention (1) was tripled compared to XantPhos, which indicates a clear increase in activity. The catalyst also remains stable at high temperatures.