Editorial pubs.acs.org/OPRD
Safety Special Feature Editorial
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papers in this special feature and to the editors (Mike Ironside, Rich Barnhart, Steve Shaw, and David Dale) for their work in pulling this feature together. Issue No. 12 of 2015 will contain the next Safety feature, so please start to think about submitting articles for that special feature.
or many years, the last issue of Organic Process Research and Development (OPR&D) has included a special feature section devoted to the safety of chemical processes, and I recommend that all process chemists and engineers read all the articles in this section to learn about potential problems in the scale-up of chemical processes. While most companies have excellent departments to study the safety of processes using calorimetry and other techniques, many smaller companies and universities do not pay enough attention to the safety issues with regard to the scale-up of potentially hazardous materials and reactions. We still receive papers at the editorial office of OPR&D describing, for example, oxidations on a large scale in which there has been no safety assessment of the hazards of operating a process using oxygen or a peroxide reagent with a flammable solvent at high temperaturethese papers are returned to the author for further work. But I still occasionally get the comment, “There are no safety issues since we haven’t seen any exotherms or runaways on scale-up”. These are famous last words! I hope the authors live to regret them. The potential for runaway is present in many processes, particularly oxidations, but often the runaway potential does not appear until something else goes wrong such as a delay in the process, a bad batch of reagent or catalyst, an impurity which inhibits the catalyst, and so forth. I remember being present in the early 1980s beside a 2500 L reactor during the 40th batch of an oximation reaction (nitrosation of an active methylene with sodium nitrite-HCl) combined with the conversion of the CNOH group to CO (using formaldehyde) in the same pot when the reaction slowly began to warm from −40 °C and eventually peaked at about 90 °C over about 30 min, despite extra cooling being applied to the process. The reaction must have been inhibited until we had added all of the formaldehyde, and then we had the typical runaway scenario: all of the reagents in the pot and no method of controlling the exotherm. Fortunately, the solvent in this case was mostly water. But it was a frightening experience seeing a large batch out of control and having to decide whether to stay and incorporate extra cooling (we were frantically adding blocks of dry ice to the isopropanol external cooling heat exchanger to try to remove the heat from the process) or whether to evacuate the building and watch from the outside of the building while the exotherm took its course. The decision to stay was taken after seeing that the rate of change of temperature was gradually decreasing. This incident persuaded me of the importance of full safety evaluation of processes before scale-up, and I eventually purchased a Contalab reactor/calorimeter (this was before the RC1 was launched) for this purpose and introduced set procedures for the evaluation process. Therefore, we must all keep up with the literature of safety and learn from others’ mistakes. This is why each year this issue contains a review of the literature, picking out articles which may be from journals that process chemists do not normally read or papers in which the safety message may have been buried. My thanks to all authors who have contributed to the © XXXX American Chemical Society
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Trevor Laird, Editor-in-Chief AUTHOR INFORMATION
Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
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dx.doi.org/10.1021/op500365u | Org. Process Res. Dev. XXXX, XXX, XXX−XXX
