Bronopol (CAS 52-51-7): Complete Technical Data Reference

Bronopol is a white to pale-yellow crystalline solid at room temperature, with the yellow coloration in commercial samples attributed to chelation of trace iron during the manufacturing process rather than impurity. The compound's melting point is commonly cited as approximately 130°C, though due to its polymorphic characteristics, Bronopol undergoes a lattice rearrangement at 100-105°C that can sometimes be wrongly interpreted as the melting point in less careful analysis.

Common synonyms include: 2-Bromo-2-nitropropane-1,3-diol; 2-Bromo-2-nitro-1,3-propanediol; 1,3-Propanediol, 2-bromo-2-nitro-; 2-Nitro-2-bromo-1,3-propanediol; and beta-Bromo-beta-nitrotrimethyleneglycol. Common abbreviations include Bronopol (the INN), BNPD, and BNPK. The substance is also sold under trade names including Bronocot, Bronosol, Bronotak, Onyxide 500 (Lonza), Lexgard Bronopol, and the Myacide range (AS Plus, BT, Pharma BP).

Bronopol shows a strong affinity for polar solvents over non-polar ones. Solubility at 22-25°C includes water (28% w/v), methanol (89%), ethanol (56%), and isopropanol (41%), while solubility in liquid paraffin and mineral/vegetable oils is below 0.5%, reflecting its preference for the aqueous phase in two-phase formulation systems. Solid Bronopol can be stored for 3 years or longer under recommended conditions and is not significantly influenced by daylight, humidity up to 90%, or temperature up to approximately 45°C. Aqueous solutions are considerably less stable and require cold, acidic storage conditions.