Aminobenzoic acids
In chemistry , the aminobenzoic acids form a group of substances derived from both benzoic acid and aniline .
Representative
The structure consists of a benzene ring with attached carboxy (–COOH) and amino (–NH 2 ) groups as substituents . Their different arrangement ( ortho , meta or para ) result in three constitutional isomers . 2-aminobenzoic acid is known by its common name anthranilic acid .
Aminobenzoic acids | ||||||
Surname | 2-aminobenzoic acid | 3-aminobenzoic acid | 4-aminobenzoic acid | |||
other names |
o -aminobenzoic acid anthranilic acid |
m -aminobenzoic acid |
p -aminobenzoic acid PABA |
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Structural formula | ||||||
CAS number | 118-92-3 | 99-05-8 | 150-13-0 | |||
ECHA InfoCard | 100,003,898 | 100.002.477 | 100.005.231 | |||
PubChem | 227 | 7419 | 978 | |||
Molecular formula | C 7 H 7 NO 2 | |||||
Molar mass | 137.14 g mol −1 | |||||
Physical state | firmly | |||||
Brief description | white crystalline powder | |||||
Melting point | 146-148 ° C | 174 ° C | 186-189 ° C | |||
boiling point | Decomposition from 200 ° C | - | - | |||
pK s COOH | 2.05 | 3.07 | 2.38 | |||
pK s NH 2 (the conjugate acid BH + ) |
4.95 | 4.73 | ||||
Solubility in water |
5.72 g l −1 (25 ° C) | 5.9 g l −1 (20 ° C) | 4.7 g l −1 (20 ° C) | |||
GHS labeling |
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H and P phrases | ||||||
318 | 315-319-335 | 315-319-335 | ||||
280-305 + 351 + 338-313 |
261-280-302 + 352 305 + 351 + 338 |
261-280-304 + 340 305 + 351 + 338-405-501 |
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Tox data | 5410 mg kg −1 ( LD 50 , rat , oral ) | > 6000 mg kg −1 ( LD 50 , rat , oral ) |
properties
The aminobenzoic acid group includes:
- 2-aminobenzoic acid ( ortho -aminobenzoic acid ), also known as anthranilic acid
- 3-aminobenzoic acid ( meta -aminobenzoic acid )
- 4-aminobenzoic acid ( para -aminobenzoic acid ), also known as PABA
Compared to aliphatic aminocarboxylic acids, the aminobenzoic acids are present in an aqueous solution in a significantly lower proportion as zwitterions (H 3 N + -R-COO - ), since the basicity of the amino group on the phenyl ring is reduced.
Individual evidence
- ↑ a b c d Entry on 2-aminobenzoic acid in the GESTIS substance database of the IFA , accessed on March 12, 2018(JavaScript required) .
- ↑ a b c Entry on 3-aminobenzoic acid in the GESTIS substance database of the IFA , accessed on March 12, 2018(JavaScript required) .
- ↑ a b c d Entry on 4-aminobenzoic acid in the GESTIS substance database of the IFA , accessed on March 12, 2018(JavaScript required) .
- ↑ a b CRC Handbook of Tables for Organic Compound Identification , Third Edition, 1984, ISBN 0-8493-0303-6 .