Process for Pd-catalyzed hydroxycarbonylation of diisobutene: effect of solvent

Abstract

A process for Pd-catalyzed hydroxycarbonylation of diisobutene in an acetic acid solvent in the presence of a ligand having the following structure: ##STR00001##
In contrast to reaction solvents such as formic acid or 3,5,5 hexanoic acid the conversion rates were improved and greater than 90% at a reaction temperature of 120 C. and CO pressure of 40 bar.

Claims

1. A process comprising: a) adding diisobutene, forming a reaction mixture, b) adding of a compound comprising Pd, wherein the Pd is capable of forming a complex, c) adding the ligand L1: ##STR00005## d) adding acetic acid, as a solvent for the reaction mixture, e) feeding in CO, f) heating the reaction mixture such that the diisobutene is converted to the compound P1: ##STR00006##

2. The process according to claim 1, wherein the compound in step b) is 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, further comprises g) adding p-toluenesulfonic acid.

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 20 bar to 60 bar.

Description

(1) The invention is elucidated in more detail by means of a working example below.

(2) ##STR00004##

(3) A 4 ml vial was charged with [Pd(acac).sub.2] (3.05 mg, 0.25 mol %), L1 (20.64 mg, 1.0 mol %), PTSA*H.sub.2O (28.5 mg, 3.75 mol %) and an oven-dried stirrer bar. 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 (0.5 ml), acetic acid (1.5 ml) and diisobutene (DIBN) (4.0 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 pressure of CO was increased to 40 bar at room temperature. The reaction was conducted at 120 C. for 20 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.

(4) The experiment described above was repeated with variation of the solvent. All other parameters were maintained.

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

(6) TABLE-US-00001 Entry Solvent Conversion (%) 1 3,5,5-trimethylhexanoic acid 88 2 Formic acid 48 3* Acetic acid >99 *inventive process

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