Chemical Identity and Structure

5-Chloropyridazin-3-amine (CAS 1606-82-2) is a six-membered nitrogen-containing heterocycle belonging to the pyridazine family. Its core scaffold features two adjacent ring nitrogen atoms at positions 1 and 2, a primary amino group (–NH₂) at position 3, and a chlorine substituent at position 5. The molecular formula is C₄H₄ClN₃, giving a molecular weight of approximately 129.55 g/mol. The coexistence of the electron-withdrawing ring chloride and the electron-donating amino group creates a polarised aromatic system, making the molecule reactive toward both nucleophilic aromatic substitution (SNAr) at C-5 and electrophilic acylation or condensation at the amine nitrogen. This dual reactivity is the principal reason for its utility as a synthetic building block.

Research and Synthetic Applications

5-Chloropyridazin-3-amine serves as a key intermediate in the synthesis of a broad range of pharmacologically relevant targets. The C-5 chlorine undergoes SNAr reactions with amines, alcohols, and thiols under mild conditions, enabling rapid diversification of the pyridazine scaffold. The 3-amino group participates in amide bond formation, Schiff base synthesis, cyclisation reactions, and metal-catalysed cross-coupling when appropriately protected or activated.

Reported application areas include kinase inhibitor programmes, where the pyridazine ring acts as a hinge-binding motif; antimicrobial agent discovery; and the preparation of agrochemical candidates. The compound also serves as a precursor to more complex bicyclic or fused-ring systems through intramolecular cyclisation strategies.

Physicochemical Properties and Stability

As a crystalline solid at room temperature, 5-Chloropyridazin-3-amine is moderately polar owing to the amino and ring-nitrogen functionalities. It shows appreciable solubility in polar aprotic solvents such as DMSO and DMF, and in protic solvents including ethanol and methanol. Aqueous solubility is limited at neutral pH but increases under acidic conditions due to protonation of the amine or ring nitrogens.

The compound is generally stable under ambient conditions when stored properly. Prolonged exposure to moisture may promote slow hydrolysis or aggregation; therefore, storage in a tightly sealed container under inert atmosphere is recommended for long-term preservation. The material should be kept away from strong oxidising agents, strong acids, and strong bases.

Safety, Handling, and Regulatory Considerations

As with most aromatic amines and halogenated heterocycles, appropriate laboratory safety precautions should be observed when handling 5-Chloropyridazin-3-amine. Standard personal protective equipment (PPE)—including nitrile gloves, laboratory coat, and safety glasses—is recommended. Operations generating dust or aerosols should be conducted in a well-ventilated fume hood.

Users should consult the current Safety Data Sheet (SDS) supplied by Aladdin Scientific for authoritative hazard classification, first-aid measures, and disposal guidance applicable to their jurisdiction. Regulatory status may vary by country; researchers are responsible for verifying local import and use restrictions prior to procurement.

Ordering, Purity, and Quality Specifications

Aladdin Scientific offers 5-Chloropyridazin-3-amine under SKU C173335. Purity is confirmed by HPLC and/or NMR analysis in accordance with standard reagent-grade quality control procedures. A Certificate of Analysis (CoA) is available upon request and can be accessed via the product page using the specific lot number.

For bulk quantities or custom purity grades, please contact Aladdin's sales team directly. When preparing an order, researchers should confirm that the required quantity, purity specification, and packaging format meet their experimental needs. All products are subject to Aladdin's standard terms regarding returns, refunds, and shipping, as detailed in the relevant policy sections of the Aladdin website.