Method for producing tetrakis (trihydrocarbyl phosphane) palladium(0)

Abstract

Method for the production of tetrakis(trihydrocarbylphosphane)palladium(0) in organic solvent, whereby 50 to 100% by weight of the organic solvent consist of at least one polar-aprotic solvent, characterised in that a) at least one palladium compound selected from the group consisting of palladium(II) compounds and palladium(IV) compounds that are soluble in the organic solvent is reacted with b) at least one base, selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal hydrogen carbonates, alkali metal-C.sub.1-C.sub.4-alcoholates, ammonium carbonate, ammonium hydrogen carbonate, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkaline earth metal hydrogen carbonates, alkaline earth metal-C.sub.1-C.sub.4-alcoholates, and alkylamines with a total of 2 to 12 carbon atoms; c) at least one trihydrocarbylphosphane; and d) at least one organic reducing agent that is different from the remaining components that are used in the method.

Claims

1. A method for the production of tetrakis(trihydrocarbylphosphane)palladium(0) in organic solvent, whereby 50 to 100% by weight of the organic solvent consists of at least one polar-aprotic solvent, the method comprising reacting at least one palladium compound selected from the group consisting of palladium(II) compounds and palladium(IV) compounds solubilized in the organic solvent with at least one base selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal hydrogen carbonates, alkali metal-C.sub.1-C.sub.4-alcoholates, ammonium carbonate, ammonium hydrogen carbonate, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkaline earth metal hydrogen carbonates, alkaline earth metal-C.sub.1-C.sub.4-alcoholates, and alkylamines with a total of 2 to 12 carbon atoms, at least one trihydrocarbylphosphane, and at least one organic reducing agent selected from the group consisting of ascorbic acid, alkali metal salts of ascorbic acid, alkaline earth metal salts of ascorbic acid, and ammonium salt of ascorbic acid, wherein the method exhibits a tetrakis(trihydrocarbylphosphane)palladium(0) product yield ranging from 95% to 100%.

2. The method of claim 1, wherein the at least one palladium compound is selected from the group consisting of alkali tetrahalogenopalladates(II), ammonium tetrahalogenopalladates(II), alkali hexahalogenopalladates(IV), ammonium hexahalogenopalladates(IV), palladium(II) halides, palladium(II) nitrate, palladium(II) sulfate, bis(trihydrocarbylphosphane)palladium(II) dihalides, Pd(COD)Cl.sub.2, Pd(CH.sub.3CN).sub.2Cl.sub.2, Pd(C.sub.6H.sub.5CN).sub.2Cl.sub.2, and palladium(II) acetate.

3. The method of claim 1, wherein the at least one palladium compound is PdCl.sub.2.

4. The method of claim 1, wherein the at least one polar-aprotic solvent is selected from the group consisting of tertiary carboxylic acid amides, sulfoxides, ketones, lactones, lactams, nitriles, urea derivatives, sulfones, carboxylic acid esters, and carbonic acid esters.

5. The method of claim 1, wherein the at least one polar-aprotic solvent is selected from the group consisting of DMF, DMSO, acetone, gamma-butyrolactone, N-methyl-2-pyrrolidone, acetic acid ethyl ester, and acetonitrile.

6. The method of claim 1, wherein the at least one organic reducing agent is ascorbic acid.

7. The method of claim 1, wherein the three hydrocarbyl residues of the at least one trihydrocarbylphosphane are selected from the group consisting of unsubstituted aryl residues, substituted aryl residues, open chain alkyl residues, and cyclic alkyl residues, in any combination thereof.

8. The method of claim 1, wherein the at least one trihydrocarbylphosphane is triphenylphosphane.

9. The method of claim 1, wherein the at least one polar-aprotic solvent is selected from the group consisting of DMF, DMSO, acetone, gamma-butyrolactone, N-methyl-2-pyrrolidone, acetic acid ethyl ester, and acetonitrile, the at least one palladium compound is selected from the group consisting of alkali tetrahalogenopalladates(II), ammonium tetrahalogenopalladates(II), alkali hexahalogenopalladates(IV), ammonium hexahalogenopalladates(IV), palladium(II) halides, palladium(II) nitrate, palladium(II) sulfate, bis(trihydrocarbylphosphane)palladium(II) dihalides, Pd(COD)Cl.sub.2 (COD=cyclooctadiene), Pd(CH.sub.3CN).sub.2Cl.sub.2, Pd(C.sub.6H.sub.5CN).sub.2Cl.sub.2, and palladium(II) acetate, and the at least one base is selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal hydrogen carbonates, and triethylamine.

10. The method of claim 1, wherein the at least one palladium compound is PdCl.sub.2 and the at least one organic reducing agent is ascorbic acid.

11. The method of claim 9, wherein the at least one trihydrocarbylphosphane is triphenylphosphane.

12. The method of claim 1, wherein the at least one reducing agent is used, relative to palladium, in an amount equal to 1- to 3-fold of the equivalent amount required for reduction to palladium(0).

13. The method of claim 1, wherein 2-4 molar equivalents of base are used per molar equivalent of palladium(II) and 4 - 8 molar equivalents of base are used per molar equivalent of palladium(IV).

14. The method of claim 1, wherein the at least one trihydrocarbylphosphane is used in an amount equal to 4- to 6-fold of the molar equivalent, relative to palladium.

15. The method of claim 1, wherein the concentration of the palladium used in the method, relative to the organic solvent, is in the range of 0.05 mol/L to 0.25 mol/L.

16. The method of claim 1, wherein the tetrakis(trihydrocarbylphosphane)palladium(0) thus produced is separated as a solid from the liquid phase, and the separated solid is washed with water followed by further washing steps with water-miscible alcohols, and then the product is dried at reduced pressure.

17. The method of claim 16, wherein the solid tetrakis(trihydrocarbylphosphane)palladium(0) is separated from the liquid phase by filtration, centrifugation or decanting.

18. The method of claim 1, wherein the tetrakis(trihydrocarbylphosphane)palladium(0) thus produced is separated as a solid from the liquid phase, and the separated solid is washed with water followed by further washing steps with water-miscible alcohols and then with alkanes, and then the product is dried at reduced pressure.

19. The method of claim 18, wherein the solid tetrakis(trihydrocarbylphosphane)palladium(0) is separated from the liquid phase by filtration, centrifugation or decanting.

20. A method for the production of tetrakis(triphenylphosphane)palladium(0) in organic solvent, whereby 50 to 100% by weight of the organic solvent consists of at least one polar-aprotic solvent, the method comprising reacting PdCl.sub.2 solubilized in the organic solvent with a base selected from the group consisting of NaHCO.sub.3, KOH, Na.sub.2CO.sub.3 and triethylamine, triphenylphosphane, and ascorbic acid or a salt thereof, wherein the method exhibits a tetrakis(triphenylphosphane)palladium(0) product yield ranging from 97.6% to 100%.

Description

EXAMPLES

Example 1

(1) Approx. 215 g DMSO, 5.032 g PdCl.sub.2 (Pd 3.000 g, 28.19 mmol), 37.5 g PPh.sub.3 (PPh.sub.3 143.13 mmol) and 9.9 g formic acid (C.sub.6H.sub.8O.sub.6 56.25 mmol) and 6.6 g NaHCO.sub.3(78.56 mmol) were placed in a 4-necked flask, and approx. 10 g DMSO were used for rinsing. Subsequently, the mixture was stirred at room temperature for 20 minutes. Then, the suspension was heated to an internal temperature of 60° C. Once the temperature was reached, the mixture had a bright yellow colour.

(2) After stirring for a period of 2 hours at 60° C., the sample was cooled passively to room temperature (22° C.).

(3) The suspension was transferred through a Teflon hose by means of argon into a Schlenk frit (G3 frit) made inert with argon, and then filtered. The content of the flask was rinsed with 15 g of DMSO and then also transferred to the frit. This resulted in a bright red filtrate and a bright yellow filter cake.

(4) The product on the Schlenk frit was washed with 4×80 g fully de-salted water, 3×30 g isopropanol, and 3×20 g petroleum spirit. The filter cake was dried for approximately 40 minutes at reduced pressure.

(5) This resulted in a bright yellow powder.

(6) The product was then tested for its palladium content. Moreover, an IR spectrum was measured and an elemental analysis was performed.

(7) Product=32.003 g

(8) Pd content=9.15% by weight (gravimetric determination in triplicate, theoretical value 9.20 wt.-%)

(9) Pd=2.92 g (added: 3.00 g)

(10) Yield=97.6% relative to the palladium in the PdCl.sub.2 used here

(11) IR: corresponds to the reference spectrum for pure Pd(PPh.sub.3).sub.4

(12) Elemental analysis: expected for Pd(PPh.sub.3).sub.4 C, 74.84%; H, 5.23%; O, 0%; P, 10.72%; detected C, 74.30%; H, 5.35%; O<0.2%; P, 10.55%.

Examples 2-4

(13) Three other experiments were run analogous to Example 1. The only difference being the type of base that was used, while all other substances and molar amounts of substances were kept unchanged:

(14) TABLE-US-00001 Example 1 2 3 4 Base NaHCO.sub.3 KOH Na.sub.2CO.sub.3 NEt.sub.3 Palladium compound PdCl.sub.2 Reducing agent Ascorbic acid Trihydrocarbylphosphane Triphenylphosphane Solvent DMSO Yield (by .sup.31P-NMR 100% 98% 100% 100% spectroscopy)