Anthranilic acid
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| General | ||||||||||||||||||||||
| Surname | Anthranilic acid | |||||||||||||||||||||
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| Molecular formula | C 7 H 7 NO 2 | |||||||||||||||||||||
| Brief description |
colorless to yellowish, sweet-tasting leaflets |
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| properties | ||||||||||||||||||||||
| Molar mass | 137.14 g mol −1 | |||||||||||||||||||||
| Physical state |
firmly |
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| density |
1.41 g cm −3 |
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| Melting point |
146-148 ° C |
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| boiling point |
Decomposition from 200 ° C |
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| Vapor pressure |
0.1 Pa (52.6 ° C) |
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| pK s value |
2.05 |
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| solubility |
poor in water (5.72 g l −1 at 25 ° C) |
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| Refractive index |
1.578 (144 ° C) |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C | ||||||||||||||||||||||
Anthranilic acid (2-aminobenzoic acid, o -aminobenzoic acid ) is an aromatic , colorless to pale yellow, blue fluorescent carboxylic acid that is used as an intermediate in dyes, pharmaceuticals, cosmetics, photographic chemicals and fine chemicals, lubricant additives and anti-corrosion agents. It was discovered in 1841 by Carl Julius Fritzsche (1808–1871) during the alkaline degradation of indigo . The salts (carboxylates) and esters of anthranilic acid are known as anthranilates .
In addition to the two other anthranilic posture exist isomeric forms: the 3-aminobenzoic acid ( m -aminobenzoic acid) and the 4-aminobenzoic acid ( p -aminobenzoic acid ).
Extraction and presentation
Industrial production of anthranilic acid takes place through a Hofmann rearrangement of phthalimide in the presence of sodium hydroxide and sodium hypochlorite .
In another manufacturing process, 2-nitrotoluene is subjected to an intramolecular redox reaction .
use
Anthranilic acid also serves as a starting material for the synthesis of anthranilic acid derivatives, which are used as non-opioid analgesics because of their similarity to salicylic acid . Anthranilic acid itself does not have this effect. The export of the substance from Germany sometimes requires a permit (see Basic Substance Monitoring Act ), as it can serve as a starting material for addictive substances (including ketamine and methaqualone ).
Anthranilic acid now plays an important role as the starting material for the synthesis of the anthranilic acid esters, which are important as odorous substances, and of indigo as well as of medicinal substances and pesticides (acaricides). Anthranilic acid can be used for the determination and detection of Ag , Cd , Ce , Co , Cu , Hg , Mn , Ni , Pb , Pd , U and Zn .
Anthranilic acid is also the starting material for the production of methyl red , an azo dye , the sodium salt of which is used as an acid-base indicator . For this purpose, the amino group of anthranilic acid is diazotized with sodium nitrite and hydrochloric acid and then an azo coupling is carried out with N , N- dimethylaniline .
Individual evidence
- ↑ Entry on anthranilic acid. In: Römpp Online . Georg Thieme Verlag, accessed on February 21, 2014.
- ↑ a b c d e f g Entry on 2-aminobenzoic acid in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
- ↑ CRC Handbook of Tables for Organic Compound Identification , Third Edition, 1984, ISBN 0-8493-0303-6 .
- ^ HA Frediani: Refractive Index Measurements at and above Melting Point of Solids . In: Industrial & Engineering Chemistry Analytical Edition . tape 14 , no. 5 , 1942, pp. 439-441 , doi : 10.1021 / i560105a023 .
- ^ A b S. Hauptmann, J. Graefe, H. Remane: Textbook of Organic Chemistry , VEB Deutscher Verlag für Grundstoffindustrie, Leipzig 1980.
- ^ Author collective: Organikum , 22nd edition, Wiley-VCH, Weinheim 2004, p. 645.
Web links
- Synthesis of Heterocycles from Anthranilic acid and its Derivatives (PDF file; 1.08 MB)
- Synthesis and cyclization of anthranilohydroxamic acids (PDF file; 587 kB)
- Beilstein Handbook 14 E1