Chemical Identity and Physical Properties

4-Bromo-5-methyl-2H-triazole is a five-membered nitrogen-rich heterocycle belonging to the 1,2,3-triazole family. The compound features two structurally significant substituents: a bromine atom at the 4-position and a methyl group at the 5-position, with an N–H tautomeric proton at the 2-position. This substitution pattern makes the molecule an unsymmetrical triazole that can exist as a mixture of 1H and 2H tautomers in solution, a behaviour common to NH-triazoles.

The C–Br bond confers reactivity toward transition-metal-catalysed cross-coupling reactions (e.g., Suzuki–Miyaura, Buchwald–Hartwig), while the methyl group offers a site for further functionalisation under appropriate conditions. The compound is typically a solid at room temperature. Molecular weight is approximately 161.97 g/mol (calculated for C₂H₂BrN₃ plus the methyl carbon; exact value should be confirmed with the certificate of analysis).

Recommended Handling and Safety Precautions

As with most organobromine heterocycles, 4-bromo-5-methyl-2H-triazole should be handled with appropriate personal protective equipment (PPE), including nitrile gloves, safety glasses, and a laboratory coat. All weighing and transfer operations should be performed in a well-ventilated fume hood to minimise inhalation exposure to fine particulates.

Avoid contact with skin, eyes, and mucous membranes. In case of skin contact, wash thoroughly with soap and water. In case of eye contact, rinse immediately with copious amounts of water and seek medical attention. Consult the Safety Data Sheet (SDS) for the specific GHS hazard classification, pictograms, and first-aid measures before use. The SDS available from Aladdin Scientific (SKU B634578) should be reviewed prior to handling.

Dispose of waste material according to local, regional, and national regulations governing halogenated organic compounds. Do not discharge into drains or the environment.

Storage Conditions and Stability

Store 4-bromo-5-methyl-2H-triazole in a tightly sealed container in a cool, dry, and well-ventilated location, away from direct light and incompatible materials such as strong oxidisers and strong bases. Refrigerated storage (2–8 °C) is commonly recommended for long-term preservation of brominated heterocycles to minimise potential degradation or tautomeric equilibration artefacts.

Upon receiving the compound, inspect the container for integrity. If the material has been stored correctly and the container remains sealed, the compound is expected to be stable for an extended period. Always check the expiry date or retest date on the certificate of analysis (CoA) supplied by Aladdin Scientific. Once opened, re-seal immediately and consider using an inert-gas blanket (argon or nitrogen) if moisture sensitivity is a concern.

Applications in Synthesis and Research

The 1,2,3-triazole ring is a privileged scaffold in drug discovery, agrochemistry, and materials science owing to its metabolic stability, hydrogen-bonding capacity, and bioisosteric properties. 4-Bromo-5-methyl-2H-triazole serves as a valuable building block for introducing the triazole nucleus into more complex molecular architectures.

The C4 bromine serves as a handle for palladium- or copper-catalysed cross-coupling reactions, enabling C–C bond formation (Suzuki, Negishi, Sonogashira) and C–heteroatom bond formation (Buchwald–Hartwig amination, Chan–Lam coupling). The free N–H functionality allows N-alkylation or N-arylation to control regioselectivity of the triazole nitrogen substitution. These combined features make 4-bromo-5-methyl-2H-triazole particularly useful for the synthesis of pharmacologically relevant triazole derivatives, including potential kinase inhibitors, antifungal agents, and anti-inflammatory scaffolds.

In materials chemistry, triazole-containing compounds have been explored as ligands in metal–organic frameworks (MOFs) and as components of functional polymers. Researchers developing such systems may find 4-bromo-5-methyl-2H-triazole a convenient precursor.

Solubility and Formulation Guidance

NH-triazoles generally exhibit moderate polarity due to the nitrogen lone pairs and the N–H donor. 4-Bromo-5-methyl-2H-triazole is expected to show good solubility in polar aprotic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and acetonitrile, and moderate solubility in lower alcohols such as methanol and ethanol. Solubility in non-polar solvents (e.g., hexanes, diethyl ether) is anticipated to be limited.

For stock solution preparation, DMSO is the recommended solvent for most biochemical assay applications. Prepare stock solutions at a concentration verified by weighing and volumetric dilution; confirm concentration by UV–Vis spectroscopy or NMR if critical. Filter sterilise (0.2 µm) if required for cell-based assays. Note that actual solubility values should be determined experimentally, as they are not provided in the current source material.