For chemists engaged in organic synthesis, understanding the fundamental properties of chemical intermediates is paramount. 6-Hydroxy-5-nitronicotinic acid, identified by CAS number 6635-31-0, is a key heterocyclic building block whose properties dictate its utility in various synthetic pathways. This article aims to provide a comprehensive overview of its chemical identity, physical characteristics, and spectral data, essential for R&D scientists and procurement professionals.

Chemical Identity and Nomenclature

6-Hydroxy-5-nitronicotinic acid, with the molecular formula C6H4N2O5, possesses a molecular weight of approximately 184.11 g/mol. Its systematic IUPAC name is 6-hydroxy-5-nitropyridine-3-carboxylic acid. The compound is also known by several synonyms, including 5-nitro-6-hydroxynicotinic acid and 5-nitro-6-oxo-1,6-dihydropyridine-3-carboxylic acid, reflecting potential tautomeric forms or variations in naming conventions. The structure features a pyridine ring substituted at position 3 with a carboxylic acid group, at position 5 with a nitro group, and at position 6 with a hydroxyl group. This arrangement of functional groups significantly influences its chemical behavior and reactivity.

Physical and Chemical Properties

As a physical entity, 6-Hydroxy-5-nitronicotinic acid typically presents as a yellow solid. Its melting point is reported in the range of 269-271°C, indicating strong intermolecular forces, likely due to hydrogen bonding between the functional groups. The compound's density is approximately 1.7 g/cm³. While specific solubility data varies, it is generally considered to have limited solubility in water but may be soluble in polar organic solvents. Its chemical reactivity is defined by its functional groups: the nitro group can undergo reduction, the hydroxyl group can participate in esterification or etherification, and the carboxylic acid group can form salts, esters, or amides. This reactivity makes it a valuable intermediate for synthesizing more complex molecules, particularly in pharmaceutical and agrochemical applications.

Spectral Characterization for Quality Assurance

To confirm the identity and assess the purity of 6-Hydroxy-5-nitronicotinic acid, several spectroscopic techniques are routinely employed. Nuclear Magnetic Resonance (NMR) spectroscopy, specifically ¹H NMR, reveals characteristic signals for the aromatic protons on the pyridine ring, typically appearing as doublets in a specific chemical shift range (e.g., around 8.4-8.8 ppm), indicative of the substitution pattern. Infrared (IR) spectroscopy provides evidence for the presence of key functional groups: a carbonyl (C=O) stretch around 1700 cm⁻¹ from the carboxylic acid, strong absorptions for the nitro (NO₂) group around 1520 and 1350 cm⁻¹, and an O-H stretch from the hydroxyl group. Mass Spectrometry (MS) confirms the molecular weight and can provide fragmentation patterns useful for structural elucidation. High-resolution MS is employed to verify the exact molecular formula, C6H4N2O5, by providing an accurate mass measurement of the molecular ion.

Procurement and Supplier Reliability

For organizations looking to purchase 6-Hydroxy-5-nitronicotinic acid, it is crucial to partner with reliable suppliers who can guarantee product quality and consistency. Manufacturers in China, such as NINGBO INNO PHARMCHEM CO.,LTD., are key sources for this intermediate. When inquiring about the product, customers should always request a Certificate of Analysis (CoA) that includes detailed spectral data (NMR, IR, MS) and physical properties. Understanding the supplier's quality control measures and their capacity to meet demand, especially for bulk purchases (e.g., in 25 kg drums), is essential for ensuring a stable supply chain for pharmaceutical R&D, agrochemical synthesis, or other fine chemical applications. Competitive pricing and responsive technical support further enhance the value proposition.

Conclusion

6-Hydroxy-5-nitronicotinic acid is a well-defined chemical intermediate with a predictable reactivity profile, supported by comprehensive spectral data. Its role in synthesizing pharmaceuticals and agrochemicals makes it a vital component for many industries. Professionals seeking to buy this compound should prioritize detailed technical specifications and reliable sourcing from experienced manufacturers and suppliers to ensure the success of their chemical projects.