DE1118796B - Process for the preparation of aromatic haloaminocarboxylic acids and their derivatives - Google Patents

Description

Process for the preparation of aromatic haloaminocarboxylic acids and their derivatives. It is known that one can use aromatic halonitrocarboxylic acids and their derivatives with the usual reducing agents, such as iron-hydrochloric acid, zinc-hydrochloric acid, Tin (II) chloride and ammonium sulfide, or by catalytic reduction with Raney nickel can convert into the corresponding halogen amino compounds. These procedures however, have significant disadvantages. They are either cumbersome to carry out or give poor yields due to the fact that with the reduction the nitro group simultaneously eliminates the halogen in the nucleus, difficult to separate mixtures of chloramino and amino compounds are formed. In catalytic reduction, the reaction can stop at intermediate stages, so that you can nitroso or hydroxylamino compounds and their derivatives, such as Azo and hydrazo compounds.

It is also known to use 4-chloro- or 4,6-dichloro-3-nitro-1-alkylbenzenes catalytic with hydrogen and Raney nickel in solution at room temperature and 20 at to reduce to the corresponding 4-chloro- or 4,6-dichloro-3-amino-l-alkylbenzenes. It is also known to use 2-chloro-1-nitrobenzene or 4-chloro-1-nitrobenzene with hydrogen and platinum catalysts in alcohol at 25 to 30 ° C and 2; 5 to 3.0 at in 2-chlorine or 4-chloroaniline to be transferred. It is also known to use m-halonitrobenzenes with hydrogen in the presence of rhodium or copper-chromium oxide catalysts to m-haloanilines to reduce. However, all of these methods lead to aromatic when applied Halogenitrocarboxylic acids and their derivatives do not have the same beneficial effects with respect to the yield and purity of the products obtained.

Finally, it is also known that 2-chloro-4-nitrobenzoic acid and its ethyl ester and 4-fluoro-3-nitrobenzoic acid can be reduced with hydrogen and palladium in solution to the corresponding haloamino compounds. However, these processes are not suitable for large-scale production of the desired products. Platinum metals, such as palladium, are extremely expensive and, moreover, difficult to access, so that the spent catalysts must be worked up. However, as is known, these regeneration processes are very laborious and involve considerable expense. For these reasons, the processes for reducing said halonitro compounds with palladium have hitherto only been carried out in the context of experimental and research work on a laboratory scale. It has now been found that halogenated aromatic nitro carboxylic acids and their derivatives in a simple and economical way can be virtually quantitatively converted into the corresponding halogen- and amino-substituted derivatives when the respective nitro compound, as an about 10 to 25 ° / o solution in the presence of a Treated nickel-alumina catalyst at 40 to 150 ° C and under a hydrogen pressure of 80 to 120 at.

Alcohols, ethers and saturated hydrocarbons can be used as solvents be used. It is also possible, in the case of esters, with basic alcohols Use hydrohalides.

The reduction products are worked up in the usual way by evaporating the solvent and purifying the residue either by distillation, Recrystallization or by reprecipitation. Example 1 100 g of 4-chloro-2-nitrobenzoic acid are dissolved in 500 ccm of methanol and washed with sodium hydroxide solution (19 g of sodium hydroxydin 50 ccm of water). The mixture is placed in a 2-1 autoclave and mixed with 5 to 10 g of nickel-alumina catalyst. Then hydrogen (100 at) pressed and heated to 80 to 100'C. After the pressure has been approved, work is carried out. The filtrate from the catalyst is concentrated and the residue is taken up in water and 4-chloro-2-aminobenzoic acid precipitated with dilute mineral acid or acetic acid. The raw acid has one yellowish tinge, but can become pure white Substance be recrystallized or reprecipitated. Yield: 75 g (88% of theory); Mp 240 ° C.

Example 2 500 g of 2-chloro-4-nitrobenzoic acid methyl ester are added to 41 Dissolved methanol and with 40 to 50 g of nickel catalyst as in Example 1 in one 10-1 autoclave catalytically reduced. After filtering off the catalyst some of the methanol evaporates. On cooling, methyl 2-chloro-4-aminobenzoate crystallizes in long needles. The ester can be recrystallized from methanol.

Yield: 420 g (95% of theory); 106 ° C. Example 3 200 g of 2-chloro-4-nitrobenzoic acid (β-diethylaminoethylamide) hydrochloride are dissolved in 21% ethanol and mixed with 30 to 40 g of nickel-alumina catalyst. The hydrogenation conditions are: 100 atm at 40 to 45 ° C for 6 hours: After filtration Ethanol is evaporated from the catalyst and the residue with 80 ccm warm water recorded. The aqueous solution is treated with activated charcoal and then with ice cooled down. The resulting crystal slurry is filtered off with suction and washed with acetone. After drying, the 2-chloro-4-aminobenzoic acid (β-diethylaminoethylamide) hydrochloride is obtained in the form of a dihydrate.

Yield: 163 g- (800 /, of theory); F. 51'C. EXAMPLE 4 200 g of ethyl 2-bromo-4-nitrobenzoate are dissolved in 600 cc of methanol, 15 g of nickel-alumina catalyst are added and the mixture is reduced under the conditions given in Example 1. Working up is carried out as in Example 2. The ethyl 2-bromo-4-aminobenzoate is obtained. Yield: 150 g (85 ° / "of theory); mp 83'C.

Example 5 200 g of 2-chloro-4-nitrobenzoic acid β-diethylaminoethyl ester are dissolved in 11 di-n-propyl ether, mixed with 30 g of nickel-alumina catalyst and treated at 40 to 50 ° C and 100 at hydrogen pressure. After filtration from Catalyst, the propyl ether is driven off and the residue with 2N hydrochloric acid brought to the pn value 6 to 7. The aqueous solution is concentrated until Crystallization occurs on cooling. The 2-chloro-4-aminobenzoic acid-ß-diethylaminoethyl ester hydrochloride is obtained.

Yield: 155 g (75% of theory); F. 171 'C.

Claims (2)

PATENT CLAIMS: 1. Process for the preparation of aromatic haloaminocarboxylic acids and their derivatives, characterized in that aromatic Halogennitrocarbonsäuren_ or their derivatives in solution in the presence of a nickel-alumina catalyst 40 to 150 ° C and reduced under a hydrogen pressure of 80 to 120 at. 2. The method according to claim 1, characterized in that the solvent used is alcohols, ethers or saturated hydrocarbons. Documents considered: German Patent No. 812 075; Journ. At the. Chem. Soc., 49, 1094-1096 (1927); 71: 4155 (1949); 61: 3005 (1939); U.S. Patent Nos. 2,772,313, 2,791,613.