Hazards of a N-Bromosuccinimide Solution in N,N-Dimethylformamide

Following Hovione process safety screening procedures, the preparation of a 22 wt % N-bromosuccinimide (NBS) solution in N,N-dimethylformamide (DMF) was studied by means of RC1 isothermal heat flow calorimetry. The mixture revealed a sudden and rapid decomposition with off-gas release, few minutes after reaching 80 °C. This triggered a thorough thermal safety investigation using several well-established differential thermal analysis techniques. The thermal stability data obtained were used to generate a predictive model for this solution decomposition using Advanced Kinetics and Technology Solutions software. The NBS/DMF solution undergoes hazardous thermal decomposition at low temperatures, and the safe working temperature (TMRad at 24 h) for 22 wt % was established as 32 °C. There was also evidence found for an autocatalytic mechanism and the influence of the NBS concentration and the equipment’s materials of construction on the decomposition onset and overall energy output. The work described herein highlights the need for important process safety management considerations when handling the NBS/DMF solution at an industrial scale.