• Su-Yeon Ji
• Jin-Hyok Choe
• Hyok-Jun Ji
• Chol-Yong Sin
• Won-Jin Li

3,5-Diaminobenzoic acid (3,5-DABA)—the key raw material for synthesizing meglumine diatrizoate, a clinically essential X-ray contrast agent—was synthesized via the iron-hydrochloric acid reduction of 3,5-dinitrobenzoic acid (3,5-DNBA), replacing the expensive, high-pressure platinum-hydrogenation method. Systematic optimization of reaction parameters yielded 3,5-DABA with an 84.2% yield under the following conditions: iron powder particle size of 90–100 mesh, molar ratio of 3,5-DNBA to iron of 1:8, reaction temperature of 100℃, and reaction time of 9 hours. Meglumine diatrizoate is widely used in X-ray imaging of the urinary tract (detection rate of renal calculi: 98.7%), intravenous urography (glomerular filtration rate assessment), cardiovascular system (coronary stenosis visualization), uterus and fallopian tubes (tubal patency testing), and lactiferous ducts (mammary duct ectasia diagnosis) (Pyongyang Medical University, 2023). The synthesis of this contrast agent relies on 3,5-DABA as a precursor to diatrizoic acid—impurities in 3,5-DABA (e.g., residual 3,5-DNBA, iron oxides) can reduce contrast efficacy or induce adverse reactions (e.g., allergic dermatitis in 0.3–0.5% of patients) (Institute of Organic Chemistry, National Academy of Sciences of the DPRK, 2022). Conventional 3,5-DABA synthesis methods have limitations: platinum-catalyzed hydrogenation (2 MPa, 70–80℃, 84.8% yield) requires expensive noble metals and high-pressure equipment (Lesen et al., 1956). Hydrazine-mediated reduction (FeCl₃·6H₂O/activated carbon, 82.5% yield) uses toxic reagents and generates hazardous wastewater (Zhang et al., 2021). In contrast, the iron-hydrochloric acid method (atmospheric pressure, low cost) aligns with green chemistry principles and offers scalability for industrial meglumine diatrizoate production (Liu et al., 2023). Product identity was confirmed via Fourier Transform Infrared (FT-IR) spectroscopy, with spectra matching standard 3,5-DABA profiles (Sigma-Aldrich, 2024).

Meglumine; one-step reductive amination (OSRA); Raney nickel (Ra-Ni); X-ray contrast agents; pharmaceutical excipient; parameter optimization; industrial scalability

"Synthesis of 3,5-Diaminobenzoic Acid: A Critical Intermediate for Meglumine Diatrizoate Production", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.13, Issue 2, page no.g93-g100, February-2026, Available :http://www.jetir.org/papers/JETIR2602612.pdf

"Synthesis of 3,5-Diaminobenzoic Acid: A Critical Intermediate for Meglumine Diatrizoate Production", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.13, Issue 2, page no. ppg93-g100, February-2026, Available at : http://www.jetir.org/papers/JETIR2602612.pdf