JP2541882C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing anthranilic acids useful as raw materials for synthesizing medicines, agricultural chemicals, dyes, and the like. As an industrial method for producing anthranilic acid, a method is known in which phthalimide obtained from phthalic anhydride and ammonia is reacted with sodium hypochlorite and sodium hydroxide. This method is difficult to apply to various anthranilic acids having a substituent on the aromatic nucleus. [0003] As a method for synthesizing anthranilic acid having a substituent at the nucleus, for example, 4-chloroanthranilic acid, 2-nitro-4-chlorotoluene is used as a starting material and reduced to give 2-amino-4-chlorotoluene. Then, a method involving several steps of acetylation of an amino group, oxidation of a methyl group, and hydrolysis (deacetylation) is described in Journal of American Chemical Society, Vol.
It is introduced on pages 285-1288. However, this method has many steps, and it is difficult to obtain a high-quality target compound at low cost. [0004] On the other hand, a method of synthesizing anthranilic acids by using orthohalogenobenzoic acids as a raw material and ammonolyzing the same in ammonia water has already been known, but there are not many reports. For example, the former German patent of Hoechst (DRP, 14560)
4,1902) synthesizes anthranilic acid from 2-chlorobenzoic acid in aqueous ammonia at 125 ° C. using copper powder as a catalyst. However, even after the excess ammonia is removed from the reaction mixture, the resulting 4-chloroanthranilic acid contains a large amount of a copper compound insoluble in water or an organic solvent even if it is subjected to acid precipitation with a mineral acid. Therefore, it is colored from gray purple to yellowish green, and its purity is low. [0005] As a cause of this, in the ammonolysis of these orthohalogenobenzoic acids, metallic copper or a copper-containing catalyst used as a catalyst remains dissolved in the reaction mixture in the form of a copper ammonium complex compound in the reaction mixture after the reaction, and a portion thereof is partially removed. It is considered to form a stable chelate complex compound with anthranilic acids as reaction products. As a method for removing the catalyst dissolved as a copper ammonium complex compound, treatment with an alkali hydroxide aqueous solution precipitates and separates as copper oxide, treatment with alkali sulfide or alkali hydrosulfide precipitates and separates as copper sulfide, It is conceivable to adsorb and separate copper on the exchange resin, etc., but in the case of the method, the alkali hydroxide or alkali sulfide aqueous solution itself dissolves copper oxide or copper sulfide, so that it is completely precipitated as copper oxide or copper sulfide, However, this method is not practical because it has a disadvantage that a large amount of ion exchange resin is required and the operations such as desorption and regeneration are complicated. As a method for synthesizing 4-chloroanthranilic acid using 2,4-dichlorobenzoic acid as a raw material, a partial ammonolysis method in ammonia water is used.
t) [Samant, Ber., 75B, 1008 (1942)]. In a more recent report, Yakhontov and colleagues attempted synthesis using the same route [Yakhontov, LN
etal. Khim.- Farm. Zh., 21 (1), 38-49 (1987)]. Samantt uses a zero-valent metal copper alone as a catalyst and reacts it at 37 ° C. in aqueous ammonia at 120 ° C. for 4 hours, and Yacontoff et al. Use 126-129 as a catalyst using copper acetate which is a divalent copper compound.
The reaction was performed at 10 ° C. for 10 hours. However, as a result of the inventors' additional tests of each method, both methods have a low reaction conversion rate and a large amount of unreacted 2,4-dichlorobenzoic acid remains, so that the quality of the isolated product decreases. It was confirmed that. It is not easy to remove and purify unreacted raw materials mixed in the product without impairing the yield, which deviates from the original purpose of obtaining 4-chloroanthranilic acid at low cost. In addition, both methods have relatively high reaction temperatures and pressures, and thus have the disadvantage of increasing the rate of side reactions to be hydroxylated and thermal decomposition of the products in addition to the original amination reaction. It is not preferable because the material and the specifications of the device are greatly restricted. [0007] Accordingly, an object of the present invention is to provide a new route different from the route which has been conventionally practiced industrially to ammonolyse orthohalogenobenzoic acids in a single-step reaction. It is an object of the present invention to provide a method for producing the corresponding anthranilic acids at low cost, efficiently, and with high yield. Means for Solving the Problems The present inventors have conducted intensive studies to solve the problems in synthesizing the corresponding anthranilic acids by ammonolysis of such conventional orthohalogenobenzoic acids. Surprisingly, it has been found that cuprous oxide, whose oxidation state is intermediate between zero-valent metallic copper and cupric copper, is extremely effective as a catalyst for synthesizing the corresponding anthranilic acid from orthohalogenobenzoic acids. The present invention has been accomplished based on this finding. That is, the present invention provides a compound represented by the general formula (I): (Wherein, Y represents a hydrogen atom, a halogen atom, a lower alkyl group, a hydroxyl group, an alkoxy group, an acetoxy group, a nitro group, an amino group, a sulfo group, a carboxyl group, a trifluoromethyl group, or an aryl group; N is an integer of 1 to 4. M is selected from a hydrogen atom, an ammonium group, an alkali metal atom or an alkaline earth metal atom.) In producing the acids, a compound represented by the general formula (II): (In the formula, X represents a halogen atom selected from chlorine, bromine and iodine, and Y, n and M have the same meanings as described above) in the presence of a cuprous catalyst. A method for producing anthranilic acids which is reacted under heating in aqueous ammonia, wherein the copper (I) -containing catalyst comprises a combination of zero-valent metallic copper and a copper compound in an oxidized state of cupric, and A method for producing anthranilic acids, which is substantially in an oxidation state of cuprous cup due to disproportionation; and a compound represented by the general formula (I) -a: (Wherein Y ¹ represents a halogen atom, and M has the same meaning as in formula (I).) In producing anthranilic acids represented by the formula: (Wherein Y ¹ has the same meaning as in general formula (I) -a, and X and M have the same meaning as in general formula (II)). And a method for producing anthranilic acids, characterized in that the reaction is carried out in an aqueous ammonia solution under heating in the presence of (i). Hereinafter, the present invention will be described specifically. The compound represented by the general formula (II) used as a starting material in the method of the present invention is specifically 2-chlorobenzoic acid, 2-bromobenzoic acid, 2-iodobenzoic acid, 2,3-dichloro Benzoic acid, 2,4-dichlorobenzoic acid, 2,5-dichlorobenzoic acid, 2,6-dichlorobenzoic acid, 2-chloro-4-fluorobenzoic acid,
2-chloro-6-fluorobenzoic acid, 2-chloro-4,5-difluorobenzoic acid, 2,4-dichloro-5-fluorobenzoic acid, 2,3,4-trichlorobenzoic acid, 2,3,5- Trichlorobenzoic acid, 2,4,5-trichlorobenzoic acid, 2,4,6-trichlorobenzoic acid, 2,3,4,5-tetrachlorobenzoic acid, 2-chloro-4-methylbenzoic acid, 2-chloro -5-methylbenzoic acid, 2-chloro-6-
Methylbenzoic acid, 2-chloro-3-hydroxybenzoic acid, 2-chloro-4-hydroxybenzoic acid, 2-chloro-3-nitrobenzoic acid, 2-chloro-4-nitrobenzoic acid, 2-chloro-5- Nitrobenzoic acid, 4-amino-2-chlorobenzoic acid,
5-amino-2-chlorobenzoic acid, chloroterephthalic acid, 4-chloroisophthalic acid, 3,4-dichlorophthalic acid, 5-chlorotrimellitic acid, 2-chloro-4-
Trifluoromethylbenzoic acid, 1-chloro-2-naphthoic acid, 3-chloro-2-
Examples thereof include naphthoic acid, which may be not only a free acid but also an ammonium salt, an alkali metal salt such as K or Na, or an alkaline earth metal salt such as Mg or Ca. The ammonolysis reaction in the present invention is carried out in an aqueous ammonia solution which also serves as a reaction solvent, using a pressure-resistant reaction vessel. The concentration of the aqueous ammonia is preferably 10 to
It is 50% by weight, more preferably 20 to 35% by weight. If the concentration of ammonia is too low, the proportion of salicylic acid derivative by-produced increases and the pH decreases, which adversely affects the corrosion resistance of the reaction vessel material. If the concentration is too high, the by-products of the diphenylamine dicarboxylic acid type derivative will increase, and the pressure during the reaction will be extremely high industrially, which will restrict the specifications of the reactor and may cause the ammonia water to be recovered and reused. Disadvantaged. The amount of ammonia used is preferably from 3 to 1 mol of orthohalogenobenzoic acid.
The molar amount is 40 times, more preferably 6 to 25 times. If it is less than this, stirring becomes difficult, and the corrosion of the apparatus may increase. Further, even if it is used in an unnecessarily large amount, the reaction result is not improved, and only the production efficiency is reduced. The cuprous-containing catalyst used in the method of the present invention is, for example, a copper compound in an oxidation state of cuprous oxide, specifically, cuprous oxide, cuprous chloride, cuprous bromide. , Cuprous iodide, copper thiocyanate or copper cyanide. Further, the present invention uses a copper compound in an oxidized state of zero-valent metal copper and cupric acid in any combination, and as shown by the following formula, an equivalent mixture of copper metal and a cupric compound reacts. In some cases, the disproportionation reaction of the ionic valence may substantially exist in an oxidation state of cuprous. Cu + Cu ²⁺ → 2Cu ⁺ Copper compound in the oxidation state of cupric (oxide, hydroxide, fluoride, chloride, bromide, iodide, One or more selected from acetate, carbonate, perchlorate, nitrate, phosphate, sulfate and the like), specifically, cupric oxide, cupric hydroxide, fluoride Cupric, cupric chloride,
Cupric bromide, cupric iodide, ammonium cupric chloride, copper acetylacetonate, copper borofluoride, copper formate, copper acetate, copper citrate, copper oxalate, copper stearate,
Copper carbonate, copper perchlorate, copper nitrate, copper phosphate, copper pyrophosphate, copper sulfate and the like. One or more of these copper compounds are used in the presence of metallic copper. Metallic copper may be added in the form of powder, cutting, or any other shape. Of these, copper compounds in the oxidized state of metallic copper and cuprous copper are easily oxidized in the aqueous ammonia by oxygen in the air, and are converted to copper ammonium complex compounds in the oxidized state of cupric acid to act as a catalyst. Therefore, when a catalyst is added to the reaction vessel, it is essential to immediately purge air with an inert gas such as nitrogen. The amount of the copper-containing catalyst used in the present invention is 0.001 to 1.0 gram atom, preferably 0.1 to 0.1 gram atom, in terms of copper atom, based on 1 mol of the starting material, orthohalogenobenzoic acid. 02-0.3 gram atom. As described above, it is usually used as a cuprous compound, but it may be used in combination with a zero-valent metal copper and a cupric compound. In this case, the metal copper and the cupric compound do not necessarily have to be equivalent, and if the valence is disproportionated and the copper content falls within the range of the catalyst amount, one of them becomes excessive. Is also good. If the amount of cuprous copper is less than this, the reaction rate becomes slow, and unreacted raw materials remain. If the amount is larger than necessary, the operation of removing the catalyst in the post-treatment becomes complicated, which is not preferable. [0016] The reaction temperature is preferably 50 to 160 ° C, more preferably 70 to 120 ° C. If the reaction temperature is too low, the reaction rate will be low, and if it is too high, the rate of by-products of the salicylic acid derivative or the thermal decomposition (decarboxylation) of the target product will increase, and the yield and quality will decrease. Problems and restrictions arise in terms of In the method of the present invention, it is preferable that after the completion of the reaction, the catalyst contained in the reaction solution is treated and recovered as metallic copper. As a method for this, a. After treating the reaction mixture containing the copper-containing catalyst with a dithionite, for example, hydrosulfite (Na ₂ S ₂ O ₄ ) to precipitate metallic copper, anthranilic acids are removed from the reaction solution obtained by removing and separating the metallic copper. A method of isolating, b. The reaction mixture containing the copper-containing catalyst is treated with any hydrazine compound selected from hydrazine, hydrazine hydrate, and neutral hydrazine sulfate to precipitate metallic copper, which is then separated and removed from the reaction solution. There is a method of isolating anthranilic acids. Thus, a copper compound can be reduced to metallic copper by adding a dithionite or a hydrazine compound as a reducing agent. The amount of these reducing agents used is 0.1 to 10 mol, preferably 0.5 to 2 mol, per 1 gram atom of copper of the catalyst.
This amount corresponds to 0.0001 to 10 mol per 1 mol of the starting orthohalogenobenzoic acid. If the amount of the reducing agent is less than this, the reduction will be insufficient, and the copper compound will be mixed into the product, and the quality will deteriorate. Increasing the reducing agent beyond this is uneconomical and presents problems with wastewater treatment. Preferably, the amount of the dithionite or hydrazine compound to be used is 0.001 to 2 mol per 1 mol of the raw material orthohalogenobenzoic acid. The reducing agent used in the present invention may be added after most of the ammonia is once discharged from the reaction mixture and recovered after the reaction is completed, or may be added before the operation of recovering ammonia. Further, it may be added together with a caustic commonly used for decomposing the ammonium salt formed in the reaction. Usually, the reaction mixture is treated with a reducing agent while avoiding contact with air, and stirred in a temperature range of room temperature to 100 ° C. for several minutes to several tens of hours to precipitate metallic copper. At this time, it is preferable that the temperature is set to 80 to 100 ° C. and the dissolved ammonia is sufficiently removed under normal pressure or reduced pressure. Further, as described above, in order to decompose the ammonium salt and complete the emission of ammonia, it is preferable to add a caustic alkali. The caustic alkali is usually used in an amount of 1 to 3 mol based on 1 mol of the starting material orthohalogenobenzoic acid. When the precipitated metallic copper is separated by a method such as filtration or decantation,
A usually pale yellow clear solution containing an alkali metal salt of anthranilic acids is obtained.
When this is treated with a mineral acid, 90 to 95% of white to light yellow-brown anthranilic acids are obtained.
In high yield. According to the method of the present invention, desired anthranilic acids can be obtained with high purity and high yield only by a single-stage reaction in which ammonolysis is performed in the presence of a cuprous catalyst. According to the present invention, the reaction can be completed within several hours even under mild conditions of 80 to 100 ° C. and 3 to 6 kg / cm ² G at a lower temperature and a lower pressure than before, and the ratio of side reactions can be suppressed. High-purity anthranilic acids can be synthesized inexpensively and with good yield. In addition, since the reaction temperature and the pressure during the reaction are greatly reduced, the conditions on the equipment relating to the corrosion resistance and pressure resistance of the reaction volume can be relaxed, which is suitable for industrial implementation. Furthermore, by treating the reaction solution with a specific reducing agent after the completion of the reaction, it became possible to efficiently separate the copper compound. As a result, anthranilic acids can be synthesized from orthohalogenobenzoic acid with high purity and high yield. The present invention will be described below in more detail with reference to examples. EXAMPLE 1 190 g of 25% aqueous ammonia (2.
79 mol) and 30.0 g (0.157 mol) of 2,4-dichlorobenzoic acid were stirred and dissolved until it became an emulsion. 1.55 g (0.0157 mol) of cuprous chloride as a catalyst was added thereto, and the reaction vessel was sealed. After purging the internal air with nitrogen, the mixture was stirred and reacted at 100 ° C. for 6 hours. The internal pressure during the reaction is 4.9-4.3 kg /
cm ² G. After cooling to ambient temperature, the reaction vessel was opened under a blanket of nitrogen and the reaction mixture was withdrawn. The reaction mixture was analyzed by high performance liquid chromatography (internal standard method using o-hydroxydiphenyl as an internal standard substance) to give the following analytical values. The reaction conversion was 100%, and the selectivity for 4-chloroanthranilic acid was 96. 0.2%. 4-chloroanthranilic acid 0.1510 mol 4-chlorosalicylic acid 0.0028 mol 2,4-dichlorobenzoic acid not detected After removing the dissolved ammonia and the catalyst from the reaction mixture thus obtained, By acid precipitation with a mineral acid, 4-chloroanthranilic acid having a purity of 98.6% was converted to 2
5.8 g were obtained. When recrystallized with an alcohol-water mixed solvent, the purity was 99.7.
% Of 4-chloroanthranilic acid was obtained as white needles (24.1 g). 2,
The yield based on 4-dichlorobenzoic acid was 89.4%. Comparative Examples 1-4 Except that the catalyst was changed to use of copper metal or cupric compound alone, 4-chloroanthranilic acid was synthesized under the same reaction conditions as in Example 1. The results are shown in Table 1. [Table 1] Example 2 In the same reaction vessel as in Example 1, 190 g (2.79 mol) of 25% aqueous ammonia and 30.0 g (0.157 mol) of 2,3-dichlorobenzoic acid were charged and stirred to obtain an emulsion. It dissolved until it became a state. To this, 1.12 g of cuprous oxide of the catalyst (0.00783)
Mol) was added and the reaction vessel was sealed. After purging the air with nitrogen,
Stirred for hours. The internal pressure during the reaction was 6.8 to 6.5 kg / cm ² G. Analysis of the reaction mixture in the same manner as in Example 1 gave the following analysis values. The conversion of the reaction was 99.8%, and the selectivity for 3-chloroanthranilic acid was 97.4%. 3-chloroanthranilic acid 0.1529 mol 3-chlorosalicylic acid 0.0012 mol 2,3-dichlorobenzoic acid 0.0003 mol Example 3 In a reaction vessel similar to that of Example 1, 170 g of 20% aqueous ammonia (2 .00 mol) and 37.6 (0.240 mol) of 2-chlorobenzoic acid were added and dissolved by stirring. To this, 1.19 g (0.012 mol) of cuprous chloride was added, the reaction vessel was sealed, and air was purged with nitrogen. The mixture was stirred at 85 ° C. for 6 hours to be reacted. The internal pressure during the reaction is 3.
It was 0 to 2.6 kg / cm ² G. The analysis of the reaction mixture in the same manner as in Example 1 gave the following analysis values. The conversion of the reaction was 100%, and the selectivity for anthranilic acid was 97.2%. Anthranilic acid 0.2333 mol Salicylic acid 0.0012 mol Orthochlorobenzoic acid Not detected Example 4 150 g (2.20 mol) of 25% aqueous ammonia and cuprous iodide in the same reaction vessel as in Example 1. 43 g (0.00751 mol) was added, the reaction vessel was sealed, and then air was purged with nitrogen. While stirring, 90 g of an aqueous solution of K salt of 2,4-dichlorobenzoic acid (30.0 g of 2,4-dichlorobenzoic acid, 50% aqueous solution of KOH 17
. 5 g and 42.5 g of water were mixed and dissolved by heating at 85 ° C.) with nitrogen. Stirred at 90 ° C. for 8 hours. The internal pressure during the reaction was 3.4 to 3.2 kg / cm ² G. When the reaction mixture was analyzed in the same manner as in Example 1, the following analysis values were obtained. The conversion of the reaction was 99.9%, and the selectivity for 4-chloroanthranilic acid was 95.9%. 4-chloroanthranilic acid 0.1505 mol 4-chlorosalicylic acid 0.0034 mol 2,4-dichlorobenzoic acid 0.00016 mol Example 5 As in Example 1, 25% aqueous ammonia and 2,4-dichloro Benzoic acid was added, and 0.500 g (0.00787 mol) of metallic copper and 0.562 g of cupric oxide were used as a catalyst.
(0.00707 mol), and reacted by stirring at 100 ° C. for 6 hours after purging with nitrogen. When the reaction mixture was analyzed in the same manner as in Example 1, the following analysis values were obtained. The conversion of the reaction was 99.9%, and the selectivity for 4-chloroanthranilic acid was 96.3%. Examples 6 to 11 The compositions shown in Table 2 were charged into 300 ml of a reaction solution according to Examples 1 to 5, and the reaction was carried out under the reaction conditions shown in Table 2. . The results were obtained in Examples 1 to 5.
The results are shown in Table 3. [Table 2] [Table 3] Example 12 3.4 g (0.016 mol) of sodium hydrosulfite (content 85%) and 32 g of a 48% sodium hydroxide solution were added to the reaction mixture finally obtained in Example 1.
(0.38 mol) and heated to 100 ° C. while avoiding contact with air to discharge excess ammonia. After cooling to room temperature under a nitrogen seal, precipitated copper compounds such as metallic copper were separated by filtration. The filterability was very good. Water is added to make up a total amount of 250 g, and the solution is precipitated with 35% hydrochloric acid until the pH becomes 5 to 6, filtered, washed with water, and dried. The purity is 98.6%, and the copper content is Cu (the same applies hereinafter).
15 ppm, 25.8 g of 4-chloroanthranilic acid as a white powder was obtained. When recrystallized with an alcohol-water mixed solvent, 4-chloroanthranilic acid having a purity of 99.7% and a copper content of 6 ppm (hereinafter, referred to as Cu) was converted into white needle-like crystals by 2%.
4.1 g were obtained. The yield based on 2,4-dichlorobenzoic acid was 89.4%. Example 13 The same operation as in Example 12 was carried out except that sodium hydrosulfite used in Example 12 was changed to 8.0 g (0.16 mol) of human azine monohydrate.
23.9 g (yield: 88.7%) of 4-chloroanthranilic acid having a purity of 99.6%, a copper content of 8 ppm, and white needles was obtained.

Claims (1)

Claims: 1. A compound of the general formula (I) -a (Wherein, Y ¹ represents a halogen atom, and M is selected from a hydrogen atom, an ammonium group, an alkali metal atom, or an alkaline earth metal atom.) In producing anthranilic acids represented by the general formula: (II) -a (In the formula, X represents a halogen atom selected from chlorine, bromine and iodine, and Y ¹ and M have the same meanings as described above.) An orthohalogenobenzoic acid represented by the following formula: A method for producing anthranilic acids, wherein the reaction is carried out under heating in aqueous ammonia. 2. The process of claim 1 wherein the cuprous catalyst is a copper oxide, chloride, bromide, iodide, thiocyanate or cyanide in the cuprous oxidation state. 3. A compound of the general formula (I) (Wherein, Y represents a hydrogen atom, a halogen atom, a lower alkyl group, a hydroxyl group, an alkoxy group, an acetoxy group, a nitro group, an amino group, a sulfo group, a carboxyl group, a trifluoromethyl group, or an aryl group; N is an integer of 1 to 4. M is selected from a hydrogen atom, an ammonium group, an alkali metal atom or an alkaline earth metal atom.) In producing the acids, a compound represented by the general formula (II): (In the formula, X represents a halogen atom selected from chlorine, bromine and iodine, and Y, n and M have the same meanings as described above) in the presence of a cuprous catalyst. A method for producing anthranilic acids which is reacted under heating in aqueous ammonia, wherein the copper (I) -containing catalyst comprises a combination of zero-valent metallic copper and a copper compound in an oxidized state of cupric, and A process for producing anthranilic acids, which is substantially in a cuprous oxidation state by disproportionation. 4. A compound of the general formula (I) (Wherein, Y represents a hydrogen atom, a halogen atom, a lower alkyl group, a hydroxyl group, an alkoxy group, an acetoxy group, a nitro group, an amino group, a sulfo group, a carboxyl group, a trifluoromethyl group, or an aryl group; N is an integer of 1 to 4. M is selected from a hydrogen atom, an ammonium group, an alkali metal atom or an alkaline earth metal atom.) In producing the acids, a compound represented by the general formula (II): (In the formula, X represents a halogen atom selected from chlorine, bromine and iodine, and Y, n and M have the same meanings as described above) in the presence of a cuprous catalyst. A method for producing anthranilic acids which are reacted under heating in aqueous ammonia, wherein the amount of the cuprous catalyst used is 0.00 relative to 1 mol of orthohalogenobenzoic acid in terms of copper atoms.
A method for producing anthranilic acids, wherein the amount is from 01 to 1 gram atom. 5. A compound of the general formula (I) (Wherein, Y represents a hydrogen atom, a halogen atom, a lower alkyl group, a hydroxyl group, an alkoxy group, an acetoxy group, a nitro group, an amino group, a sulfo group, a carboxyl group, a trifluoromethyl group, or an aryl group; N is an integer of 1 to 4. M is selected from a hydrogen atom, an ammonium group, an alkali metal atom or an alkaline earth metal atom.) In producing the acids, a compound represented by the general formula (II): (In the formula, X represents a halogen atom selected from chlorine, bromine and iodine, and Y, n and M have the same meanings as described above) in the presence of a cuprous catalyst. A process for producing anthranilic acids which is reacted under heating in aqueous ammonia, wherein the reaction mixture containing the cuprous catalyst is treated with dithionite to precipitate metallic copper, which is removed and separated. A method for producing anthranilic acids, comprising isolating anthranilic acids from the reacted reaction solution. 6. A compound of the general formula (I) (Wherein, Y represents a hydrogen atom, a halogen atom, a lower alkyl group, a hydroxyl group, an alkoxy group, an acetoxy group, a nitro group, an amino group, a sulfo group, a carboxyl group, a trifluoromethyl group, or an aryl group; N is an integer of 1 to 4. M is selected from a hydrogen atom, an ammonium group, an alkali metal atom or an alkaline earth metal atom.) In producing the acids, a compound represented by the general formula (II): (In the formula, X represents a halogen atom selected from chlorine, bromine and iodine, and Y, n and M have the same meanings as described above) in the presence of a cuprous catalyst. A method for producing anthranilic acids which is reacted under heating in aqueous ammonia, wherein the reaction mixture containing the cuprous catalyst is hydrazine, hydrazine hydrate, or any hydrazine compound selected from neutral hydrazine sulfate. A method for producing anthranilic acids, comprising isolating anthranilic acids from a reaction solution obtained by removing metallic copper by removing the anthranilic acids from the reaction solution. 7. The method according to claim 5, wherein the amount of the dithionite or the hydrazine compound is 0.001 to 2 mol based on 1 mol of the starting material orthohalogenobenzoic acid.