Method for producing halogen-N,N-dimethylbenzylamines

Abstract

The invention relates to a method for producing halogen-N,N-dimethylbenzylamines wherein halogen=chlorine or bromine, preferably chloro-N,N-dimethylbenzylamines, preferably ortho-chloro-N,N-dimethylbenzylamine (o-Cl-DMBA), by reductive amination in the absence of sulfur.

Claims

1. A method for producing halogen-N,N-dimethylbenzylamines, the method comprising reductive amination of halogenbenzaidehyde with dimethyiamine in the presence of: hydrogen; an acid selected from the group consisting of formic acid, acetic acid, and propionic acid; and at least one catalyst selected from the group consisting of palladium, platinum, ruthenium, nickel, cobalt, nickel-containing catalyst and cobalt-containing catalyst, wherein the reductive amination is conducted: at a hydrogen pressure of 5 to 250 bar, at a temperature of 30-250 C., with a molar ratio of the halogenbenzaidehyde to dimethylamine of 1:2-5, and without the addition of sulfur or further cocatalysts selected from the group consisting of metal oxides or metal mixed oxides, zeolites, metal salts of mineral acids, ammonium salts of mineral acids, metal salts of organic acids, ammonium salts of oroanic acids, acidic ion exchangers, and mixtures thereof.

2. The method as claimed in claim 1, wherein: the halogen is chlorine or bromine; and the reductive amination is done at a temperature of 50 to 150 C. at a hydrogen pressure of 10 to 220 bar.

3. The method as claimed in claim 1, wherein the catalysts are nickel (Ni) catalysts or cobalt (Co) catalysts produced by leaching out from Ni or Co alloys, Ni or Co on supports selected from the group SiO.sub.2, Al.sub.2O.sub.3, pumice, carbon in the form of skeletal catalysts, elemental Ni(Co) sponge, as Ni oxide, Co oxide, Raney nickel, Raney cobalt.

4. The method as claimed in claim 1, wherein: an amount of catalyst used in the reductive amination is 0.1-25% by weight based on the substrate to be hydrogenated; and an amount of the acid used in the reductive amination is 0.1-10% by weight.

5. The method as claimed in claim 1, wherein the reductive amination is conducted without solvents.

6. The method as claimed in claim 1, further comprising conducting the reductive amination in the presence of at least one solvent selected from the group consisting of methanol, ethanol, isopropanol, butanol, toluene, xylene, cyclohexane, isooctane, tetrahydrofuran, dioxane, methyl tert-butyl ester and ethyl acetate.

7. The method as claimed in claim 1, wherein the molar ratio of the halogenbenzaldehyde to dimethyiamine is 1:1.51-10, and the method comprises conducting the reductive amination at a temperature of 50-150 C., and at an H.sub.2 pressure of 10-220 bar.

8. The method as claimed in claim 1, wherein: an amount of catalyst used in the reductive amination is 1.5-12.5% by weight based on the substrate to be hydrogenated; and an amount of the add used in the reductive amination is 0.5-5% by weight.

9. The method as claimed in claim 1, wherein the acid is acetic acid.

10. The method as claimed in claim 1, wherein: the halogen is chlorine, and the halogenbenzaldehyde is o-chlorobenzaldehyde; the reductive amination is conducted at a temperature of 50-150 C., and at an H.sub.2 pressure of 10-220 bar; the at least one catalyst is a Ni or Co catalyst produced by leaching out from Ni or Co alloys, Ni or Co on supports selected from the group SiO.sub.2, Al.sub.2O.sub.3, pumice, carbon in the form of skeletal catalysts, elemental Ni(Co) sponge, as Ni oxide, Co oxide, Raney nickel, Raney cobalt, and an amount of catalyst used in the reductive amination is 1.5-12.5% by weight based on the substrate to be hydrogenated; and the acid is acetic acid, and an amount of the add used in the reductive amination is 0.5-4% by weight.

Description

EXAMPLES

(1) 150 g (1.06 mol) of o-chlorobenzaldehyde, 3 g (0.05 mol) of glacial acetic acid and 6 g of nickel catalyst (a catalyst from HC Starck GmbH) were introduced together in a 0.7 L VA autoclave. The autoclave was closed, and at room temperature 213.6 g (4.74 mol) of dimethylamine were injected. Hydrogen was then used to establish a pressure of 50 bar and the system was heated to 100 C. After reaching the target temperature, the internal pressure was increased to 200 bar with hydrogen and maintained. As soon as the pressure of the subsequently supplied hydrogen remained constant, the mixture was then stirred for 30 min at 100 C. When the hydrogen absorption was complete and after cooling to room temperature, the reaction mixture was discharged (294.5 g of crude product, without work-up) and solid fractions of catalyst and by-products were separated off by filtration. The product is analyzed by gas chromatography and the yield is determined on the basis of this.

(2) TABLE-US-00001 Molar ratio Yield of o-Cl-benzal- o-ClN,N- Exper- dehyde:dimeth- dimethyl- iment Solvent I/C Parameters ylamine benzylamine 1 without C 50 bar, 150 C., 1:1.5 0.7 2 without I 50 bar, 150 C. 1:4.5 55.5 3 without C 150 bar, 150 C. 1:1.5 50.7 4 without I 150 bar, 150 C. 1:4.5 73.3 5 without C 50 bar, 90 C. 1:1.5 78.1 6 without I 50 bar, 90 C. 1:4.5 81.9 7 without C 150 bar, 90 C. 1:1.5 81.1 8 without I 150 bar, 90 C. 1:4.5 90.6 9 without I 100 bar, 120 C. 1:3.sup. 85.5 C = comparison, I = according to the invention

(3) It is clearly evident from the examples that significantly better yields are attained at a molar ratio of o-chlorobenzaldehyde to dimethylamine of 1:>1.5.