4-aminobenzoic acid
Description
4-Aminobenzoic acid (CAS 150-13-0), commonly known as PABA or para-aminobenzoic acid, is an aromatic amino acid derivative used as a key building block in pharmaceutical synthesis.
Its bifunctional structure, carrying both an amine and a carboxylic acid group, makes it a reactive intermediate for producing dyes, UV absorbers, and active pharmaceutical ingredients.
In pharmaceuticals, PABA serves as a precursor in the synthesis of local anesthetics such as benzocaine and procaine, as well as folate-class compounds for various medical uses.
Textile and leather processors use it as an intermediate in azo dye production, where it contributes to colorfast, high-affinity dye systems for natural and synthetic fibers.
In sunscreen and personal care formulations, PABA derivatives function as UV-B absorbing agents, though demand has shifted toward its ester forms in recent years.
It also acts as a crosslinking and surface-modifying agent in specialty polymer and coating applications, providing versatility across multiple industrial chemical sectors.
4-Aminobenzoic acid is supplied as a white to off-white crystalline powder. Standard commercial grades include technical and pharmaceutical-grade material for diverse needs.
The pharmaceutical supply conforms to USP and BP specifications. Bulk quantities are available for industrial synthesis, with smaller quantities offered for R&D use.
Physical Properties
| Melting Point | 188.5 °C |
| Boiling Point | 200 °C @ Press: 10 Torr |
| Density | 1.367-1.395 g/cm³ |
| Flash Point | 250 °C |
| Appearance | White to off white crystalline powder |
| Color | White to light yellow |
| Odor | Odorless |
| Form | Crystalline Powder |
| Water Solubility | 4.7 g/L (20 ºC) |
| Vapor Pressure | 0Pa at 25℃ |
| Refractive Index | 1.5323 (estimate) |
| pH | 3.5 (5g/l, H2O, 20℃) |
| Log P | 0.96 at 25℃ |
Safety & Handling (Learn More)
Trade & Regulatory
| HS Code | 29224995 |
| Storage Class | 11 - Combustible Solids |
| WGK (Germany) | 3 |
Documentation
Other Names
para-aminobenzoic acid|p-carboxyphenylamine|p-carboxyaniline|p-aminobenzoic acid|gamma-aminobenzoic acid|aniline-4-carboxylic acid|4-carboxyphenylamine|4-carboxyaniline|PABA
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