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| Names | |||
|---|---|---|---|
| Preferred IUPAC name 2-Aminobenzoic acid[1] | |||
| Systematic IUPAC name 2-Aminobenzenecarboxylic acid | |||
Other names
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| Identifiers | |||
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3D model (JSmol) | |||
| 471803 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| DrugBank |
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| ECHA InfoCard | 100.003.898 | ||
| EC Number |
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| 3397 | |||
| KEGG |
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| RTECS number |
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| UNII | |||
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| Properties | |||
| C7H7NO2 | |||
| Molar mass | 137.138 g·mol−1 | ||
| Appearance | white or yellow solid | ||
| Odor | odorless | ||
| Density | 1.412 g/cm3 | ||
| Melting point | 146 to 148 °C (295 to 298 °F; 419 to 421 K)[3] | ||
| Boiling point | 200 °C (392 °F; 473 K) (sublimes) | ||
| 0.572 g/100 mL (25 °C) | |||
| Solubility | very soluble inchloroform,pyridine soluble inethanol,ether,ethyl ether slightly soluble intrifluoroacetic acid,benzene | ||
| logP | 1.21 | ||
| Vapor pressure | 0.1 Pa (52.6 °C) | ||
| Acidity (pKa) |
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| −77.18·10−6 cm3/mol | |||
Refractive index (nD) | 1.578 (144 °C) | ||
| Thermochemistry | |||
Std enthalpy of formation(ΔfH⦵298) | −380.4 KJ/mol | ||
| Hazards | |||
| GHS labelling: | |||
  | |||
| Danger | |||
| H318,H319 | |||
| P264,P280,P305+P351+P338,P310,P337+P313 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | > 150 °C (302 °F; 423 K) | ||
| > 530 °C (986 °F; 803 K) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 1400 mg/kg (oral, rat) | ||
| Safety data sheet (SDS) | External MSDS | ||
| Legal status | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Anthranilic acid is anaromatic acid with theformula C6H4(NH2)(CO2H) and has a sweetish taste.[5][6][7] The molecule consists of a benzene ring,ortho-substituted with acarboxylic acid and anamine. As a result of containing both acidic and basicfunctional groups, the compound isamphoteric. Anthranilic acid is a white solid when pure, although commercial samples may appear yellow. The anion [C6H4(NH2)(CO2)]−, obtained by the deprotonation of anthranilic acid, is calledanthranilate. Anthranilic acid was once thought to be a vitamin and was referred to as vitamin L1 in that context, but it is now known to be non-essential in human nutrition.[8]
Although not usually referred to as such, it is anamino acid. Solid anthranilic acid typically consists of both the amino-carboxylic acid and thezwitterionic ammonium carboxylate forms, and has amonoclinic crystal structure with space group P21.[9] It istriboluminescent.[10] Above 81 °C (178 °F; 354 K), it converts to anorthorhombic form with space group Pbca, which is not triboluminescent; a non-triboluminescent monoclinic phase with similar structure is also known.[10]
In 1840-1841,Carl Julius Fritzsche was able to extract and crystallize two acids from the products of reaction ofindigo dye withcaustic potash, which he called chrysanilic and anthranilic acids after their colors before purification (golden yellow and black respectively) and the plant anil (Indigofera suffruticosa).[11][12] The former was identified as ortho-carboxy anil of indoxyl-2-aldehyde only in 1910[13] while the latter was identified as salicylamide already in 1843 byCahours.[14]
Many routes to anthranilic acid have been described. Industrially it is produced fromphthalic anhydride, beginning with amination:
The resulting sodium salt of phthalamic acid is decarbonylated via aHofmann rearrangement of the amide group, induced byhypochlorite:[15]
A related method involves treatingphthalimide with sodiumhypobromite in aqueous sodium hydroxide, followed by neutralization.[16] In the era whenindigo dye was obtained from plants, it was degraded to give anthranilic acid.
Anthranilic acid was first obtained by base-induced degradation of indigo.[17]
Anthranilic acid is biosynthesized fromchorismic acid by the action ofanthranilate synthase. In organisms capable of tryptophan synthesis, anthranilate is a precursor to theamino acidtryptophan via the attachment ofphosphoribosyl pyrophosphate to theamine group. After then, cyclization occurs to produceindole.
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Industrially, anthranilic acid is an intermediate in the production ofazo dyes andsaccharin. It and itsesters are used in preparingperfumes to mimicjasmine andorange, pharmaceuticals (loop diuretics, such asfurosemide) and UV-absorber as well ascorrosion inhibitors for metals andmold inhibitors insoy sauce.
Anthranilate-based insect repellents have been proposed as replacements forDEET.
Fenamic acid is a derivative of anthranilic acid,[18]: 235 which in turn is a nitrogenisostere ofsalicylic acid, which is theactive metabolite ofaspirin.[18]: 235 Severalnon-steroidal anti-inflammatory drugs, includingmefenamic acid,tolfenamic acid,flufenamic acid, andmeclofenamic acid are derived from fenamic acid or anthranilic acid and are called "anthranilic acid derivatives" or "fenamates".[19]: 17
Anthranilic acid can be diazotized to give thediazonium cation [C6H4(CO2H)(N2)]+. This cation can be used to generatebenzyne,[20] dimerized to givediphenic acid,[21] or undergodiazonium coupling reactions such as in the synthesis ofmethyl red.[22]
It reacts withphosgene to giveisatoic anhydride, a versatile reagent.[23]
Chlorination of anthranilic acid gives the 2,4-dichloro derivative, which can undergoreductive coupling to form abiaryl compound.[24]
It is also aDEA List I Chemical because of its use in making the now-widely outlawed euphoric sedative drugmethaqualone (Quaalude, Mandrax).[25]
