PROCESS FOR HYDROFORMYLATION OF PENTENOIC ESTERS

Abstract

Process comprising the process steps of:

a) initially charging a pentenoic ester,
b) adding a ligand of structure 1 or 2:

##STR00001##

and a compound comprising a metal atom selected from: Rh, Ru, Co, Ir,
c) supplying H.sub.2 and CO,
d) heating the reaction mixture to convert the pentenoic ester to 5-formylpentanoic esters.

Claims

1. Process comprising the process steps of: a) initially charging a pentenoic ester, b) adding a ligand of structure 1 or 2: ##STR00006## and a compound comprising a metal atom selected from: Rh, Ru, Co, Ir c) supplying H.sub.2 and CO, d) heating the reaction mixture to convert the pentenoic ester to 5-formylpentanoic esters.

2. Process according to claim 1, wherein the conversion is effected at a temperature of 80 C. to 130 C. and a pressure of 1 to 20 bar.

3. Process according to claim 1, wherein the conversion is effected at a temperature of 90 C. to 120 C. and a pressure of 1 to 15 bar.

4. Process according to claim 1, wherein the metal in process step b) is Rh.

5. Process according to claim 1, wherein the ligand has the structure 1: ##STR00007##

6. Process according to claim 5, wherein the conversion is effected in one phase.

7. Process according to claim 1, wherein the ligand has the structure 2: ##STR00008##

8. Process according to claim 7, wherein the conversion is effected in a two-phase system.

Description

GENERAL PROCEDURE SPECIFICATIONS

[0024] The solvents used were dried using a Pure Solv drying apparatus from Innovative Technology Inc.

[0025] NMR spectra were recorded with Bruker AC 250, ARX 300 and AVANCE 500 instruments at 20 C., wherein the signals of the solvent used (CD.sub.2CI.sub.2,H:5.32 ppm) serve as an internal standard. Signal assignment was performed using .sup.1H experiments and the .sup.1H spectra of the pure substances. n-Regioselectivity was determined by means of the signals of the aldehyde function protons. These were in the range of 9-10 ppm, wherein the aldehyde group proton of the n-aldehyde is recognizable as a triplet. The signals of the corresponding protons of the i-aldehydes split into doublets and appear at lower chemical shifts.

[0026] Gas chromatograms were recorded by means of Hewlett Packard Agilent GC HP6890 and 7890A instruments, both fitted with FI detectors. A calibration to quantify the amounts of substance contained in the substrates and in the reaction products methylvaleric acid and formylpentanoic esters (5-FMP) was also performed and finally used to calculate conversions and yields.

[0027] The hydroformylations were performed in a HEL HP Chem-Scan II 8-vessel autoclave fitted with a pressurestat and a thermostat, gas flow measuring means and a magnetic stirrer, and having a respective vessel volume of 20 mL.

[0028] Methyl 4-pentenoate (M4P) was used as the substrate for the experiments.

Performance of the Experiments for Homopeneous Catalysis (One Phase)

[0029] For the homogeneously catalyzed experiments the desired ligand is weighed into a suitable Schlenk tube under inert conditions. The ligand is finally dissolved in absolute toluene and admixed with a previously prepared solution of the precursor Rh(CO).sub.2acac in toluene. The reactor vessels of the autoclave are subsequently purged with argon and charged with the preprepared solutions and the corresponding substrate is added. The reactor vessels are sealed and purged 5 times with argon (pressurized up to 6 bar each time). This is followed by heating to 50 C. and forcing the argon out of the reactor vessel with synthesis gas. This is achieved by 3-fold pressurization with synthesis gas (up to 10 bar) and subsequent decompression. Finally, the reaction solution is brought to reaction temperature and pressurized with synthesis gas until the reported pressure is achieved. The reaction mixture is now stirred for 24 hours at constant temperature and constant pressure. This is followed by slow cooling to room temperature. Samples are taken for analysis.

Ligands

[0030] ##STR00005##

[0031] Ligands 1 and 2 are employed in processes according to the invention. Ligands 3, 4 and 5 are comparative ligands.

Results of the Homogeneous Catalysis (One Phase)

[0032] The data and results for the respective homogeneously catalyzed reactions are reported in the tables which follow. The reactions were each performed at 100 C. and 5 bar of pressure. The concentration of the dissolved Rh complex is 100 ppm based on the mole fraction.

Methyl 4-pentenoate

[0033]

TABLE-US-00001 Ligand Rh:L:M4P Yield [%] n-regioselectivity [%] 1* 1:4:2000 90.7 91.7 4 1:4:2000 68.8 87.2 5 1:4:2000 78.3 46.0 *inventive process L: Ligand M4P: Methyl 4-pentenoate

Performing the Two-Phase Catalysis

[0034] For the two-phase catalysis initially the desired ligand was weighed into a suitable Schlenk tube under argon. The ligand is subsequently dissolved by addition of deionized water and admixed with the precursor solution. The mixture is thoroughly commixed and subsequently blanketed with absolute toluene. The autoclaves are then prepared as described above and charged. When the reaction mixture is at reaction temperature and pressure it is stirred for 24 hours at constant temperature and constant pressure. After cooling to room temperature samples are taken for analysis.

Results of the Two-Phase Catalysis

[0035] The data and results for the performed reactions are reported in the tables which follow. The reactions were performed at 110 C. and under 10 bar of pressure. The concentration of the dissolved Rh complex is 100 ppm based on the mole fraction.

Methyl 4-pentenoate

[0036]

TABLE-US-00002 Ligand Rh:L:M4P Yield [%] n-regioselectivity [%] 2* 1:4:2000 90.5 95.5 3 1:4:2000 83.6 98.2 *inventive process L: Ligand M4P: Methyl 4-pentenoate

[0037] As is shown by the experiments the problem is solved by the inventive process.