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US4994606A
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Process for the preparation of 4,5-difluoroanthranilic acid from 4,5-difluorophthalic anhydride or 4,5-difluorophthalic acid
Assignee: Occidental Chemical Corp
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Filing: 1990-06-04
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Granted: 1991-02-19
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Expires: 2010-06-04
Abstract
Abstract 4,5-Difluoroanthranilic acid may be prepared by decarboxylating 4,5-difluorophthalic anhydride or 4,5-difluorophthalic acid by heating in dimethyl acetamide, N-methyl-2-pyrrolidone or quinoline, optionally by reaction with copper, copper oxide, copper salts, or halides and salts of Zn, Cd, Ag and Ni as a catalyst, whereby 3,4-difluorobenzoic acid is formed; nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Inventors
- 👤 Lawrence B. Fertel
- 👤 Henry C. Lin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:31
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/347; C07C51/377; C07C51/38; C07C201/00; C07C201/06; C07C201/08; C07C227/00; C07C227/04
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
84 words
A process for the preparation of 4,5-difluoroanthranilic acid which comprises dissolving a starting material selected from the group consisting of 4,5-difluorophthalic anhydride and 4,5-difluorophthalic acid in a solvent selected from the group consisting of dimethyl acetamide, N-methyl-2-pyrrolidone and quinoline to form a solution, and heating said solution at a temperature between 175 and 215° C. to form 3,4-difluorobenzoic acid, nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Claim 2
Dependent Claim
84 words
A process for the preparation of 4,5-difluoroanthranilic acid which comprises dissolving a starting material selected from the group consisting of 4,5-difluorophthalic anhydride and 4,5-difluorophthalic acid in a solvent selected from the group consisting of dimethyl acetamide, N-methyl-2-pyrrolidone and quinoline to form a solution, and heating said solution at a temperature between 175 and 215° C. to form 3,4-difluorobenzoic acid, nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Claim 3
Dependent Claim
21 words
A process according to claim 1 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 4
Dependent Claim
31 words
A process according to claim 1 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 5
Dependent Claim
105 words
A process for the preparation of 4,5-difluoroanthranilic acid which comprises dissolving 4,5-difluorophthalic anhydride in a solvent selected from the group consisting of dimethyl acetamide, N-methyl-2-pyrrolidone and quinoline to form a solution, adding to the solution a catalytic amount of a catalyst selected from the group consisting of Cu, Cu 2 O, CuO, copper salts, and oxides and salts of Zn, Cd, Ag and Ni and heating said solution at a temperature between 120 and 215° C. to form 3,4-difluorobenzoic acid, nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Claim 6
Dependent Claim
105 words
A process for the preparation of 4,5-difluoroanthranilic acid which comprises dissolving 4,5-difluorophthalic anhydride in a solvent selected from the group consisting of dimethyl acetamide, N-methyl-2-pyrrolidone and quinoline to form a solution, adding to the solution a catalytic amount of a catalyst selected from the group consisting of Cu, Cu 2 O, CuO, copper salts, and oxides and salts of Zn, Cd, Ag and Ni and heating said solution at a temperature between 120 and 215° C. to form 3,4-difluorobenzoic acid, nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Claim 7
Dependent Claim
21 words
A process according to claim 4 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 8
Dependent Claim
31 words
A process according to claim 4 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 9
Dependent Claim
12 words
A process according to claim 4 wherein said catalyst is metallic copper.
Claim 10
Dependent Claim
21 words
A process according to claim 7 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 11
Dependent Claim
31 words
A process according to claim 7 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 12
Dependent Claim
13 words
A process according to claim 4 wherein the catalyst is Cu 2 O.
Claim 13
Dependent Claim
21 words
A process according to claim 10 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 14
Dependent Claim
31 words
A process according to claim 10 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 15
Dependent Claim
11 words
A process according to claim 4 wherein the catalyst is CuO.
Claim 16
Dependent Claim
21 words
A process according to claim 13 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 17
Dependent Claim
31 words
A process according to claim 13 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 18
Dependent Claim
109 words
A process for the preparation of 4,5-difluoroanthranilic acid which comprises heating dissolving 4,5-difluorophthalic acid in a solvent selected from the group consisting of dimethyl acetamide, N-methyl-2-pyrrolidone and quinoline to form a solution, adding to the solution a catalytic amount of a catalyst selected from the group consisting of Cu, Cu 2 O, and CuO, copper salts, and oxides and salts of Zn, Cd, Ag and Ni and heating said solution at a temperature between 120° C. to 2l5° C. to form 3,4; -difluorobenzoic acid, nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Claim 19
Dependent Claim
109 words
A process for the preparation of 4,5-difluoroanthranilic acid which comprises heating dissolving 4,5-difluorophthalic acid in a solvent selected from the group consisting of dimethyl acetamide, N-methyl-2-pyrrolidone and quinoline to form a solution, adding to the solution a catalytic amount of a catalyst selected from the group consisting of Cu, Cu 2 O, and CuO, copper salts, and oxides and salts of Zn, Cd, Ag and Ni and heating said solution at a temperature between 120° C. to 2l5° C. to form 3,4; -difluorobenzoic acid, nitrating said 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid, and reducing said 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.
Claim 20
Dependent Claim
31 words
A process according to claim 16 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 21
Dependent Claim
21 words
A process according to claim 16 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 22
Dependent Claim
12 words
A process according to claim 16 wherein the catalyst is metallic copper.
Claim 23
Dependent Claim
21 words
A process according to claim 19 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 24
Dependent Claim
31 words
A process according to claim 19 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 25
Dependent Claim
13 words
A process according to claim 16 wherein the catalyst is Cu 2 O.
Claim 26
Dependent Claim
21 words
A process according to claim 21 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 27
Dependent Claim
31 words
A process according to claim 22 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
Claim 28
Dependent Claim
11 words
A process according to claim 16 wherein the catalyst is CuO.
Claim 29
Dependent Claim
21 words
A process according to claim 29 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with a mixture of iron and HCl.
Claim 30
Dependent Claim
31 words
A process according to claim 25 wherein said 2-nitro-4,5-difluorobenzoic acid is reduced by reaction with sodium formate in the presence of a catalytically effective amount of a palladium on charcoal catalyst.
References Cited (Backward Citations)
CA701795A
Cited
DE3409244A1
Cited
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