INTRODUCTION
4-Aminobenzoic acid, commonly abbreviated as PABA, is an aromatic amine and carboxylic acid compound. It consists of a benzene ring substituted with an amino group (–NH₂) in the para position to a carboxylic acid group (–COOH). It appears as a white to slightly yellow crystalline powder and is sparingly soluble in water but soluble in alcohol and ether.
MANUFACTURE
PABA can be synthesized through various chemical processes. A common industrial method includes:
A. Nitration of Toluene followed by Amination and Oxidation
B. Alternate methods:
1. Hydrolysis of ethyl 4-aminobenzoate (an ester) using acid or base.
2. Reduction of 4-Nitrobenzoic acid.
| Synonym | p-Aminobenzoic acid |
| CAS no. | 150-13-0 |
| EINECS no. | 205-753-0 |
| Molecular formula | C₇H₇NO₂ |
| Molecular weight | 137.14 |
| Structure |  |
APPLICATIONS
| Pharmaceutical Industry |
|---|
| Intermediate in the synthesis of – Local anesthetics (e.g., benzocaine, procaine) – Sulfonamide antibiotics (as a structural analog) |
| Biochemistry & Nutrition |
|---|
| Was once classified as Vitamin Bx, but not essential for humans. |
| Still important for bacterial growth—some bacteria synthesize folic acid from PABA. |
| Used in Schilling tests for vitamin B12 absorption. |
| Industrial Applications |
|---|
| Intermediate for dyes and pigments. |
| Used in the manufacture of azo dyes. |
| Component in the polymer industry (e.g., in aramid fibers). |
| Analytical Chemistry |
|---|
| Used as a standard or reagent in analytical methods and research studies involving folate metabolism. |
SPECIFICATIONS…USP
| Test | Unit | Specification |
|---|---|---|
| Appearance | – | White to slight yellow, crystalline powder |
| Solubility | – | Slightly soluble in wáter, freely soluble in alcohol. It dissolves in dilute solutions of Alkali hydroxides |
| Identification | ||
| a. IR spectrum | – | The infrared transmittance spectrum of the “4-amino benzoic acid” should be in concordant with spectrum of standard |
| b. By HPLC | – | The retention time of the major peak of the sample solution should correspond to that of the standard solution. |
| Loss on drying | % | NMT 0.2 |
| Residue on ignition | % | NMT 0.1 |
| Heavy metals | ppm | NMT 20 |
| Related substances by HPLC | ||
| a. 4-Nitrobenzoic acid | % | NMT 0.2 |
| b. Benzocaine | % | NMT 0.2 |
| c. Any individual impurity | % | NMT 0.1 |
| d. Total impurities | % | NMT 0.5 |
| Related substances by GC | ||
| a. Aniline | ppm | NMT 10 |
| b. p-Toluidine | ppm | NMT 10 |
| Assay by HPLC (on dry basis) | % | NLT 98.0 – NMT 102.0 |
PACKING
25 kg HDPE drum.
STORAGE
Store at dry place away from light & moisture.
REACH Status
Not registered.
ExSyn offers PABA on commercial scales and welcomes enquiries. Our exceptional quality and service will make ExSyn your supplier of choice! If you need any additional information or SDS, please contact us.
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