Process for Pd-catalyzed hydroxycarbonylation of diisobutene: ligand/Pd ratio

Abstract

Process for Pd-catalyzed hydroxycarbonylation of diisobutene:ligand/Pd ratio.

Claims

1. A process for hydrocarbonylation of diisobutene to the corresponding carboxylic acid P1 comprising the process steps of: a) adding diisobutene, forming a reaction mixture, b) adding a compound comprising Pd, wherein the Pd is capable of forming a complex, c) adding ligand L1: ##STR00004## wherein the ligand L1 is added in an amount in the range from 1.25 mol to 2.0 mol of ligand per mole of Pd, d) adding acetic acid, e) feeding in CO, f) heating the reaction mixture such that the diisobutene is converted to the compound P1: ##STR00005##

2. The process according to claim 1, wherein the compound in process step b) is selected from: PdCl.sub.2, PdBr.sub.2, Pd(acac).sub.2, Pd(dba).sub.2 (dba=dibenzylideneacetone), or PdCl.sub.2(CH.sub.3CN).sub.2.

3. The process according to claim 1, wherein the ligand L1 is added in an amount in the range from 1.5 mol to 1.75 mol of ligand per mole of Pd.

4. The process according to claim 1, wherein the reaction mixture is heated to a temperature in the range from 80 C. to 160 C. in process step f).

5. The process according to claim 1, wherein the CO is fed in in process step e) such that the reaction proceeds under a CO pressure in the range from 10 bar to 40 bar.

6. The process according to claim 1, wherein the process comprises the additional process step g): g) addition of sulfuric acid.

Description

(1) The object of the invention was to provide a process affording good conversion in the Pd-catalyzed hydroxycarbonylation of diisobutene (DIBN). This reaction should be carried out in one step.

(2) The object is achieved by a process according to claim 1.

(3) Process comprising the process steps of:

(4) a) addition of diisobutene,

(5) b) addition of a compound comprising Pd, wherein the Pd is capable of forming a complex,

(6) c) addition of the ligand L1:

(7) ##STR00001##

(8) wherein the ligand L1 is added in an amount he range from 1.0 mol to 2.0 mol of ligand per mole of Pd,

(9) d) addition of acetic acid,

(10) e) feeding in CO,

(11) f) heating the reaction mixture such that the diisobutene is converted to the compound P1:

(12) ##STR00002##

(13) In one variant of the process, the compound in process step b) is selected from: PdCl.sub.2, PdBr.sub.2, Pd(acac).sub.2, Pd(dba).sub.2 (dba=dibenzylideneacetone), PdCl.sub.2(CH.sub.3CN).sub.2.

(14) In one variant of the process, the compound in process step b) is Pd(acac).sub.2.

(15) In one variant of the process, the ligand L1 is added in an amount in the range from 1.25 mol to 1.75 mol of ligand per mole of Pd.

(16) In one variant of the process, the reaction mixture is heated to a temperature in the range from 80 C. to 160 C. in process step f), preferably to a temperature in the range from 100 C. to 140 C.

(17) In one variant of the process, the CO is fed in in process step e) such that the reaction proceeds under a CO pressure in the range from 10 bar to 40 bar, preferably in the range from 10 bar to 30 bar.

(18) In one variant of the process, this process comprises the additional process step g) g) addition of sulfuric acid.

(19) The invention is more particularly elucidated hereinbelow with reference to working examples.

(20) ##STR00003##

(21) A 4 ml vial was charged with [Pd(acac).sub.2] (1.75 mg, 0.25 mol %), L1 (4.44 mg, 0.375 mol %), H.sub.2SO.sub.4 (3.1 mg, 1.4 mol %) and a stirrer bar that had been dried in an oven. The vial was then sealed with septa (PTFE-coated styrene-butadiene rubber) and a phenol resin cap. The vial was evacuated and refilled with argon three times. H.sub.2O (0.29 ml), acetic acid (0.85 ml) and diisobutene (DIBN) (2.3 mmol) were added to the vial with a syringe. The vial was placed in an alloy plate, which was transferred to an autoclave (300 ml) of the 4560 series from Parr Instruments under argon atmosphere. After flushing the autoclave three times with CO, the CO pressure was increased to 15 bar at room temperature, and subsequently increased to a pressure of 25 bar with N.sub.2. The reaction was conducted at 120 C. for 3 h. On conclusion of the reaction, the autoclave was cooled down to room temperature and cautiously decompressed. Isooctane (100 l) was then added as internal standard. Conversion was measured by GC analysis,

(22) The above-described experiment was repeated while varying the L1/Pd ratio. All other parameters were maintained.

(23) The results are compiled in the following table.

(24) TABLE-US-00001 Entry L1/Pd (mmol/mmol)-L1 (mol %) Conversion (%) 1* 1.5/1-0.375 92 2* 2/1-0.5 83 3 3/1-0.75 74 4 4/1-1.0 69 *inventive process

(25) As the experimental results show, the object is achieved by the inventive process.