4-Aminobenzoic acid (also known as para-aminobenzoic acid or PABA because the number 4 carbon in the benzene ring is also known as the para position) is an organic compound with the formula H2NC6H4CO2H. PABA, a white-grey crystalline substance, is only slightly soluble in water. It consists of a benzene ring substituted with an amino group and a carboxyl group.

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| IUPAC name 4-Aminobenzoic acid |
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| Other names para-Aminobenzoic acid; p-Aminobenzoic acid; PABA; Vitamin B10; Vitamin Bx; Bacterial vitamin H1 |
| CAS Number | 150-13-0 |
| ChEBI | CHEBI:30753 |
| ChEMBL | ChEMBL542 |
| ChemSpider | 953 |
| DrugBank | DB02362 |
| Jmol interactive 3D | Image |
| KEGG | D02456 |
| PubChem | 978 |
| UNII | TL2TJE8QTX |
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| Chemical formula | C7H7NO2 |
| Molar mass | 137.14 g·mol−1 |
| Appearance | White-grey crystals |
| Density | 1.374 g/mL |
| Melting point | 187 to 189 °C (369 to 372 °F; 460 to 462 K) |
| Boiling point | 340 °C (644 °F; 613 K) |
| Solubility in water | 1 g/170 mL (25 °C) 1 g/90 mL (90 °C) |