Discovery chemist makes unstable compound
A discovery chemist made some nitropropene for use a a "building block". However after about 4-5 days, the material had gone black. A further batch was made, this in turn also went black.
A new batch was tested with an Accelerating Rate Calorimeter (ARC), and the Safety Scientist was careful to start the run at room temperature, rather than the default 50°C. In doing he managed to ascertain that the material was decomposing exothermically at ambient temperature, and therefore the reason for the discolouration was an exothermic decomposition.
The exothermicity of the decomposition had not been observed as the material had only been made in very small quantities, and therefore the heat loss of such small samples was so great that a runaway reaction did not ensue.
Lessens Learnt
- Even discovery chemists must be aware of the potential nature of some compounds to runaway exothermically - if this preparation had been scaled up then there was the possibility of an incident.
- When compounds are showing obvious signs of degredation at "normal" temperatures, it is best to try to test the material at ambient, rather than carrying out a "standard" safety testing procedure, which might involve a higher temperature start point.