DE1643264A1 - Process for the preparation of aminoanilides - Google Patents

Description

Process for the preparation of aminoanilides

The present invention relates to a new process for the preparation of aminoanilides by catalytic hydrogenation of nitroanilides.

It is known that nitroanilines in the presence of Raney nickel in solvents such as alcohols, aqueous alcohols, ethers, benzene, toluene, chlorobenzene in smooth reaction in the transfer corresponding phenylenediamines. If, on the other hand, an attempt is made to add nitroanilides under analogous reaction conditions hydrogenate, the hydrogenation does not start at all or it comes to a standstill after a short time.

It has now surprisingly been found that aminoanilides of the general formula I

NH ₂

(D

in which R is an optionally substituted aliphatic

1 2 or aromatic hydrocarbon radical and R and R each a hydrogen atom, halogen atom, in particular a chlorine or

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Bromine atom, a lower alkyl, alkoxy, phenyl or alkyl mercapto group mean, by catalytic hydrogenation of nitroanilides of the general formula II

NO ₂

_n 2 / r - (id

ⁿ MH
• I

C = O

1 2

in which R, R and R have the meaning mentioned, in the presence can be produced by molar hydrogen in a smooth reaction if the hydrogenation is carried out in a solvent in the presence of Raney nickel and an organic or inorganic acid whose dissociation constant at room temperature is greater than 5 »10" *, executing first the organic or inorganic acid and then the Raney nickel is added to the reaction mixture.

It is an essential feature of the process of the invention that the organic or inorganic acid precedes the Raney nickel be added to the reaction mixture. When adding acid and catalyst in reverse order, the jumps Surprisingly, hydrogenation does not occur at all or it comes to a standstill after a short time.

Aliphatic hydrocarbon radicals R generally contain 1 to 12, preferably 2 to 8, carbon atoms and can also carry inert substituents such as aryl, aroxy, lower alkoxy groups or bromine or chlorine atoms.

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Aromatic hydrocarbon radicals R are preferred those with up to 10 carbon atoms in the ring system are considered, which are still inert substituents such as chlorine atoms, may contain lower alkoxy, lower alkyl groups.

Suitable carboxylic acids on which the radicals R are based are for example formic acid, acetic acid, propionic acid, butyric acid, caprylic acid, ß-chloropropionic acid, methoxyacetic acid, Phenylacetic acid, benzoic acid, o-, m-, p-chlorobenzoic acid, o-, m-, p-methoxybenzoic acid, m-trifluoromethybenzoic acid, o <-naphthoic acid, phthalic acid.

Individual examples of the nitroanilides to be used as starting material in the process of the invention are m-nitroacetanilide, o-nitro-p-acetanisidine, m-nitrobenzoylanilide _s ¹ I-chloro-2-nitroacetanilide, 3-nitro-4- (p-chlorobenzoylamino) phenol, 5-hexahydrobenzoylamino-2,4-dimethyl-1-nitrobenzene.

Examples of the inorganic acids used in the method of the invention are sulfuric acid, hydrochloric acid, phosphoric acid, perchloric acid. Suitable organic acids are preferably aliphatic mono- or dicarboxylic acids having 1 to 8, preferably 1 to H, carbon atoms, such as formic acid, acetic acid, propionic acid, chloroacetic acid, oxalic acid, and ethylhexanoic acid. For practical reasons, acetic acid is preferred. In general, 0.1 to 2, preferably 0.5 to 1 wt.? Acid (calculated 100 %) , based on the nitroanilide used.

Organic solvents, for example, are used for the hydrogenation Solvents such as alcohols, ethers, esters, optionally halo-

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Generated aromatic hydrocarbons or water or mixtures of these solvents are suitable. There are ■ for example methanol, ethanol, ethyl acetate, benzene, chlorobenzene, dioxane, tetrahydrofuran, glycol monomethyl ether, N-methylpyrrolidone. The weight ratio of nitroanilide to solvent can vary within wide limits. In general, preferably 10 to 50 wt% nitroanilide used 5 to 100,., Based on the solvent.

The nickel catalyst used is generally 0.2 to 4, advantageously 1.0 to 2.5% by weight , based on the nitroanilide.

The hydrogenation is generally carried out at temperatures between 10 and ^100.degree. C., preferably between 45 and 75.degree. The hydrogenation can be carried out at atmospheric pressure or under slightly reduced pressure. However, it is advantageous to work at hydrogen pressures of 0.2 to 10 atmospheres, in particular 0.5 to atmospheres. In general, the hydrogenation takes from 2 to 8 hours, depending on the reaction temperature and the hydrogen pressure and how intensively the reaction mixture is agitated.

The aminoanilides obtained are isolated from the reaction mixture in a manner known per se, for example by filtering off the nickel catalyst and distilling off the solvent from the piltrate. The end products can or by recrystallization from a suitable solvent, e.g. ethanol.

The aminoanilides are valuable intermediates, for example for the synthesis of dyes or insecticides.

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The parts given in the examples are parts by weight.

example 1

2000 parts of m-Nitroaeetanilid melting point of I ¹ Io to l47 ° C / ater was added in 10000 parts of V with stirring. After adding 20 parts of glacial acetic acid, about 45 parts of an aqueous Raney nickel suspension containing about 20 parts of active nickel are added. The apparatus is then flushed with hydrogen free of oxygen and the mixture obtained is kept at a hydrogen pressure of 1.8 to 2 atmospheres with vigorous mixing at 60 to 70 ^° C. until no more hydrogen is absorbed, which is reached after 5 hours. After displacing the remaining hydrogen with nitrogen, and settling of the Raney nickel the hydrogenation, the catalyst is separated off and the resulting solution concentrated in vacuo at 60 to 7O ⁰ C to dryness. 1667 parts of a product with a melting point of 83 ° to 84 ° C. are obtained, which product contains 1,630 parts of m-aminoacetanilide (97.7 % of theory). By recrystallization from methanol 87 receives a pure m-amino acetanilide of mp. 87.5 to ⁰ C.

If the procedure is as described in the example, using o- or p-nitroacetanilide instead of m-nitroacetanilide, o-aminoacetanilide is obtained in a yield of 91.4 % and p-aminoacetanilide in a yield of 94.6%.

If other acids to be used according to the invention are used instead of acetic acid, the procedure is otherwise as in the example described, the following hydrogenation times result up to complete hydrogenation: _g_

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Hydrogenation time (hours)

20 parts of formic acid 5 to 6

20 parts of oxalic acid 5 to 7

20 parts of 96% strength by weight sulfuric acid 9 to 20 parts of 36% strength by weight hydrochloric acid 5 to 6 20 parts of 80% strength by weight phosphoric acid 8 to 9.

The procedure is as described in the example, but the acid is only added to the reaction after the nickel catalyst has been added. If the mixture is added, either no hydrogenation takes place or it comes to a standstill after a few minutes.

Example 2

2,000 parts of o-nitro-p-acetanisidine recrystallized from methanol and having a melting point of 150 to 15 ° C. are introduced into 5,000 parts of methanol and 5,000 parts of water with stirring. After adding 25 parts of glacial acetic acid, 50 parts of an aqueous Raney nickel suspension containing 25 parts of active nickel are added. The procedure is otherwise as described in Example 1, the hydrogenation being completed after 8 to 10 hours. The aqueous-methanolic solution is concentrated after separation of the catalyst, adding 1, 700 parts of m-amino-acetanisidin of mp. 100-101 ⁰ C is obtained (99 ^% of theory).

Example 3

2,000 parts of 3-nitrobenzoylanilide with a melting point of 151 to 152 ° C registered in 8,000 parts of methanol with stirring. After adding 20 parts of glacial acetic acid, 50 parts of an aqueous Raney nickel suspension, which contains 25 parts of active nickel, added,

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The mixture obtained is hydrogenated at 58 to 60 ° C. and a hydrogen pressure of about 0.5 atm. The hydrogenation is complete after 6 to 8 hours. The cooled hydrogenation solution is separated from the nickel catalyst. The end product is precipitated from the solution obtained by adding ice water, filtered off and dried at 60 ° C. in a vacuum. This gives 1,490 parts of 3-aminobenzoylanilide with a melting point of 120 ° to 121 ° C. in a yield of ~ »85 % of theory.

Example k

2000 parts of 4-chloro-2-nitroacetanilide of mp. '97 to 98 ⁰ C are introduced into 10,000 parts of benzene while stirring. After adding 20 parts of glacial acetic acid, 50 parts of an aqueous Raney nickel suspension containing 30 parts of active nickel are added to the mixture. The mixture obtained is hydrogenated at 56 to 59 ° C. and 0.5 to 1 atm. Hydrogen pressure. After 4 to 5 hours, the VJas ser st off recording is over. Thereafter, the resulting residue in methanol is added 4-chloro-2-aminoacetanilids evaporated because of the poor solubility of the formed in benzene, the benzene was added, the methanolic Anilidlösung separated from the catalyst and the solution finally concentrated at 60 to 70 ⁰ C to dryness. This gives ⁱ -chloro-2-aminoacetanilide with a melting point of > k up to 135 ° C. in a yield of 75 % of theory.

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Claims (1)

- δ - O.Z. 25 307 Patent entitlement Process for the preparation of Aminoanlllden the general Formula I. NH. In which R is an optionally substituted aliphatic or 1 2 aromatic hydrocarbon radical and R and R each one Hydrogen atom, halogen atom, in particular a chlorine or bromine atom, a lower alkyl, alkoxy, phenyl or alkylmercapto group mean, by catalytic hydrogenation of nitroanilides of the general formula II NCU (II) 1 2 in which R, R and R have the meaning mentioned, in the presence of molar hydrogen, characterized in that the hydrogenation is carried out in a solvent in the presence of Raney nickel and an organic or inorganic acid whose dissociation constant at room temperature is greater than 5 * 10 "1st, executes, whereby first the organic or inorganic acid and then the Raney nickel are added to the reaction mixture. Badische Anilin- & Soda-Pabrik AG 109824/2120