Controlled Aqueous Synthesis of 5-Diazobarbituric Acid with Spectroscopic and Chromatographic Characterization
Kashyapkumar B. Desai, M. Preetham, Nilesh Prakash Badgujar, R. Jaganathan, Karuppiah NagarajIntroduction:
Diazo compounds are important synthetic intermediates, but they are not widely used because they are unstable and difficult to prepare. The objective of this research was to facilitate a controlled, reproducible, and eco-friendly synthesis of 5-diazobarbituric acid under mild aqueous conditions, while guaranteeing safety, high yield, and analytical accuracy.
Methods:
We used aqueous diazotization-coupling to prepare 5-Diazobarbituric acid from aminoguanidine hydrogen carbonate and barbituric acid, both low-toxicity precursors. The stoichiometric ratios, acidity, temperature (between 0 and 100 °C), and rate of nitrite addition were all carefully adjusted. Controlled acidity and crystallization were used to separate the product. We used FT-IR, UV-visible spectroscopy, 1H/13C NMR, and HPLC to check the structure and purity.
Results:
The FT-IR study showed that diazo was made with the vN≡N band at 2176 cm⁻¹. The UVvisible spectra showed a transition from π to π* in the range of 450 to 500 nm. NMR spectroscopy verified C5 diazo substitution while maintaining the barbituric acid core. The HPLC test showed that the substance was 99.7% pure and that the yield was 98.5%. The best results were seen when the AGHC: BA molar ratio was 0.1:0.12 and the AGHC: HCl ratio was 0.1:0.411.
Discussion:
It was very important to control the acidity, temperature, and rate of reagent addition to stabilize the guanylazide intermediate and reduce negative effects. The results show that careful optimization enablesfragile diazo systems to work reliably.
Conclusion:
This study provides practical recommendations for optimizing diazotization processes in sensitive organic synthesis by introducing a standardized and reproducible aqueous method for synthesizing high-purity 5-diazobarbituric acid. This method is in line with current ideas in green chemistry and controlled synthesis.