Process of production of 2,5-dimethylphenol

Abstract

The present invention relates to a new method to produce 2,5-dimethylphenol (2,5-DMP).

Claims

1. A process for producing a compound of formula (Ia): ##STR00017## wherein the process comprises reacting a the compound of formula (III): ##STR00018## with a compound of formula (IV): ##STR00019## wherein R.sup.1 is H or Si(CH.sub.3).sub.3, in the presence of a catalyst which comprises at least one Au(I) complex of formula (VI):
YAu(I)Z(VI), wherein Z is an anion, which is selected from the group consisting of [BX.sub.4].sup., [PX.sub.6].sup., [SbF.sub.6].sup., [ClO.sub.4].sup., CF.sub.3COO.sup., sulfonates, tetra(3,5-bis(trifluoromethyl)phenyl)borate (BAr.sub.F.sup.), tetraphenylborate, and an anion of formula (VII): ##STR00020## wherein Q represents a phenyl or a C.sub.1-8-alkyl, X is a halogen atom, and Y is an organic ligand selected from the group consisting of ligands (Y.sup.1) to (Y.sup.10): ##STR00021## ##STR00022##

2. The process according to claim 1, wherein Z is an anion selected from the group of ions consisting of [BF.sub.4].sup., [PF.sub.4].sup., [SbF.sub.6].sup., [ClO.sub.4].sup., CF.sub.3COO.sup., sulfonate, tetra(3,5-bis(trifluoromethyl)phenyl)borate (BAr.sub.F.sup.), tetraphenylborate, and an anion of formula (VII) ##STR00023##

3. The process according to claim 1, wherein the process comprises adding the Au(I) complex to a reaction mixture comprising the compounds of formulas (III) and (IV).

4. The process according to claim 1, wherein the Au(I) complex is formed in situ in a reaction mixture comprising the compounds of formulas (III) and (IV).

5. The process according to claim 1, wherein the Au(I) complex has a substrate to catalyst ratio which is 2:1 to 10000:1.

6. The process according to claim 5, wherein the substrate to catalyst ratio is 10:1 to 3000:1.

7. The process according to claim 1, wherein Q represents a phenyl or a C.sub.1-8-alkyl which is substituted by at least one substituent selected from the group consisting of F, Cl and NO.sub.2.

8. The process according to claim 1, wherein X is F or Cl.

Description

EXAMPLES

Example 1

(1) To a 2 mL glass bottle, fitted with a septum, a magnetic stirring bar and argon supply are added 34.55 mg of the compound of the following formula

(2) ##STR00016##
which is Y.sup.2Au(I)Cl, 30.66 mg AgSbF.sub.6 and 500 L 2,5-dimethylfuran and suspended in 1 mL dichloromethane. Then 144.2 L trimethylsilylacetylene was added b syringe. The reaction mixture was stirred for 20 hours at 40 C. A sample was taken out by syringe and analysed. 2,5-Dimethylphenol was obtained in 17% yield relative to 2,5-dimethylfuran (GC wt %).

Example 2

(3) A three-necked round bottom flask, fitted with argon supply, a thermometer and a magnetic stirring bar was charged with 121.3 mg of Y.sup.2Au(I)Cl (200 mol, 2 mol %), 99.5 mg AgSbF.sub.6 (200 mol, 2 mol %) and 10 mL of 1,2-dichloroethane. A previously prepared solution of 240 mg acetylene (10 mmol, 1 equiv.), 1.07 mL 2,5-dimethylfuran (10 mmol 1 equiv.) in 22 mL 1,2-dichloroethane was added dropwise over a period of 30 minutes. The reaction mixture, which changes its colour to red and violet over the addition time is kept at 20 C. inner temperature by using an external cooling device (ice-bath). The reaction mixture is stirred for 20 hours at 23 C. Then the saturated acetylene/1,2-dichloroethane solution is added three times with a time-lag of 1 hour. The reaction mixture is again stirred for 20 hours at 23 C. The reaction mixture is concentrated under reduced pressure (min. 10 mbar, 40 C.). The black liquid is dissolved in 30 mL ethyl acetate and 5 mL cyclohexane are added. The solution is left standing at 23 C. for 8 hours. Dark crystals containing the catalyst have formed which are filtered off. The supernatant is concentrated under reduced pressure and analyzed. The desired product was obtained in 20% yield based on dimethylfuran.

(4) 2,5-dimethylphenol can be conveniently transferred to 2,3,6-trimethylphenol by state of the art gas phase methylation.