What is Hydroxybenzotriazole Monohydrate (HOBT) BP EP USP Pharma Grade?

Hydroxybenzotriazole Monohydrate, commonly known in scientific circles as HOBT, is a staple in the world of organic synthesis and pharmaceutical development. This compound brings chemical stability and improved reactivity, making it essential for peptide coupling and other synthesis processes. Its material composition offers a single monohydrate water molecule integrated with a benzotriazole core, a structure that helps avoid unwanted side reactions. In terms of physical state, HOBT shows up as a solid with a crystalline structure—flakes, powders, or occasionally in small pearls depending on production methods, drying capabilities, and end-use demands. Each batch has its own feel under hand, ranging from fine, consistent powder to larger, glimmering flakes, with color hovering between off-white and pale beige, reflecting purity and handling conditions during synthesis.

Properties and Specifications

Peering into the molecular world, HOBT has a molecular formula of C6H5N3O·H2O and a molar mass that falls around 169.15 g/mol for the monohydrate version. Its specific density generally sits in the area of 1.57 g/cm³, though slight shifts occur with changes in water content. Labs and manufacturers work to confirm its melting point, which typically lands between 155°C and 158°C for the monohydrate. HOBT rarely comes in a liquid state; instead, the dry product dominates due to both handling ease and safer storage conditions. Those familiar with its handling will notice its moderate solubility in water—strong enough for good dispersal, not so high as to complicate control in formulation settings. The specific surface area and particle size distribution also come into play for blending with other raw materials, especially for pharmaceutical-grade batches seeking BP, EP, or USP compliance. Many producers supply certificates of analysis highlighting purity (generally above 99%), trace moisture, residual solvents, and heavy metal checks as demanded by pharmacopeial standards for pharma grade goods.

Chemical Structure and Behavior

Structurally, HOBT is built around a benzotriazole ring adorned with a hydroxy group. This pattern gives the molecule unique reactivity as a coupling assister in peptide synthesis, acting to boost reaction efficiency by suppressing negative side effects like racemization. This sets it apart from less refined coupling agents. Hydrogen bonding and aromatic stacking in the crystal lattice explain its solid, stable appearance at room temperature. HOBT handles stress with more stability compared to other hydroxytriazoles, a crucial property that keeps it reliable in storage, shipping, and daily use. That stability doesn’t erase all risk, though—industry experience shows HOBT remains heat sensitive and can decompose, sometimes energetically, if containment breaks down or heat sources run wild.

HS Code and Regulatory Aspects

Companies and customs agents tracking international shipments label pharma grade HOBT under HS Code 2933.99, which sets it in the heterocyclic compound category with nitrogen hetero-atoms. This code lines up with both import/export controls and provides a standardized tax category globally. Pharmaceutical applications for HOBT demand regulatory documentation showing chain of custody, residual solvent analysis, and absence of banned substances as listed by global authorities. Suppliers focusing on BP, EP, and USP certifications often pull out stops like third-party audits and accredited testing data, often required for drugs aiming at regulated markets.

Safety, Hazards, and Environmental Handling

Experience in handling tells us HOBT brings more precautions than many pharma raw materials. This chemical scores hazard labels for its potential to detonate or burn under certain situations, notably when heated or contaminated with incompatible substances. The powder can irritate respiratory tracts, eyes, or skin on contact, so working professionals stay ready with gloves, masks, goggles, and local ventilation. Some reports from the chemical sector document rare but headline-catching accidents with bulk HOBT leading to fires or serious decompositions. Fine-tuning the moisture content and temperature in warehouses brings big gains in risk reduction. Clearly labeled secondary containment, chemical safety training for everyone along the chain—from dock workers to lab staff—keeps the compound in its proper place and outside air, water, and landfill unless handled by a licensed waste firm.

Applications and Solutions for Safer Use

As a raw material, HOBT lands at the front end of many pharmaceutical syntheses, including peptide and oligonucleotide drugs—products that underpin today’s life-saving therapies for cancer, diabetes, and rare diseases. Peptide coupling reactions achieve higher yields and purity with HOBT on board, raising drug quality and lowering waste. Process chemists keep searching for safer analogs, with some companies shifting to on-demand synthesis or stabilized forms, such as wet moistened HOBT, to blunt explosive potential. Better robotics and automation in manufacturing sites, plus tightened supply chain controls, chart a path to fewer workplace injuries and stronger end-product traceability. Risk reduction leans on clear chemical safety data sheets, upgrades to legacy storage areas, and spreading knowledge about HOBT hazards right down to non-scientific warehouse staff. Built-in documentation, container seals, real-time sensors, and global audits close the loop for trustworthy, pharmaceutical-grade raw material supply lines.