Editorial pubs.acs.org/OPRD
Special Feature Issue: Continuous Processing
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fabricated for specific purposes. I believe one of the characteristics of those who chose science or engineering as a career is an early fascination with specialized glassware and scientific devices (anyone my age probably remembers the Edmund Scientific catalog: magnets, Fresnel lenses, etc.). For those familiar with the current crop of equipment used in lab scale continuous processing, I think you might agree that these are seductive! Who would not want to design their work to use these? I humbly thank all the authors who devoted their time, skills, and resources first to craft such innovative work and then for working with OPRD’s editors, referees, and production staff to render a well-written, informative, and clear publication. We accepted 42 manuscripts! The collection includes topics such as microwaves, electrochemistry, ionic liquids, oxidation, cyclopropanation, Schotten−Baumann reactions, ortho-lithiation, nucleotides, photochemistry, hydrogenation, continuous crystallization, lipases, and many others. Obviously, there are too many manuscripts to mention or thank in an editorial like this, but I would like to acknowledge those authors who contributed multiple manuscripts or have also thought of our journal when they have written in the past. Researchers such as Robert Augustine, Hans-René Bjørsvik, Kevin Cole, Holger Frey, Volker Hessel, Oliver Kappe, Tim Jamison, Klavs Jensen, Alexei Lapkin, Thomas LaPorte, Mats Larhed, Steven Ley, Allan Myerson, Michael Organ, Mario Pagliaro, Si-Ping Pang, Dominique Roberge, Chandrashekhar Rode, Thorsten Röder, Wen-Chung Shieh, Bernhardt Trout, and Timothy White are gratefully thanked for their loyalty, as they are the sort of authors that are critical to a viable journal. I hope that all of those authors who are seeing their names for the first time in this issue will think of us again when next they have the next nice piece of work to publish, flow chemistry or not. Bear in mind that we also accept reviews, concept manuscripts, and our most recent derivation, the short paper (in the form of Technical Note or Communication),1 wherein a single specific reaction is described in detail. If you add to this list our various highlights sections, writing an editorial, and letters to the editor, there is little reason why anyone involved in any area of process science cannot appear in OPRD. The overwhelming response to Organic Process Research & Development’s call for continuous processing papers means that we are devoting this entire issue to only the special feature; no regular manuscripts will appear this month. Even without the usual manuscripts, you will find this issue well worth reading (and later citing) when you write your own flow chemistry manuscript (I’m already planning a 2016 special issue!).
suspect there are few experienced process scientists who are not aware of the explosion of interest in continuous processing/flow chemistry for deriving safer and more costeffective processes. The appearance of journals, books, and conferences solely devoted to this subdiscipline further underlines the intense interest that continuous processing has captured in the chemical world, both for industrial applications and in academia. The allure of flow chemistry even extends to both camps within process departments: chemists and engineers, a confluence that must mean there is something special here. Rarely does a concept have such a broad and universal appeal. I have previously served as Editor for several special feature issues, but when I tackled Continuous Processing for the first time two years ago, I thought it would fly based on the volume of continuous processing themed work that Organic Process Research & Development (OPRD) had been seeing. However, I was surprised at the enthusiastic response that issue elicited! We received about twice the volume I dared hope would arrive: 32 manuscripts. Clearly, this was a concept that our readers wanted to see more of in OPRD if we extrapolated from writers to readers. And so it has come to be. Another special feature issue on continuous processing follows this editorial. But what exactly is the charm of flow chemistry that brings in so many authors? Continuous processing has many attractions to the chemists and engineers engaged in process science and scale up. A significant advantage, not always apparent, is the safety factor. If the chemistry forms unstable or explosive intermediates, flow processing minimizes the instantaneous inventory of the dangerous compound. If the kinetics can be tuned to allow fast reactions, it should be possible to keep the existence of the reactive intermediate relatively short and react it immediately to reach the desired product. In contrast, most batch reactions would require the key reaction creating the high energy intermediate be completed before proceeding onto the subsequent step. This would thus present a significant safety hazard at any scale above milligrams. This factor alone would justify the work to switch a process to flow chemistry if dangerous chemistry is involved. Related to safety is the ability to maintain low temperatures particularly for exothermic reactions, since the cross section of the reactor typically allows efficient cooling due to a small reaction volume. For instance, aryl lithiations can be temperature-sensitive and nearly impossible to carry out in batch. Flow chemistry is really the only way such reactions are realistic on scale. Other extreme conditions that would be difficult to maintain in a large volume reactor also find their way to continuous processing. We have several examples of such in this issue. It used to be that examples of continuous processing were little more than a couple of streams entering a reactor and an exit port to a quench vessel. The technology has advanced and matured. It is remarkable how clever and technically beautiful the microreactors have become. Check out the figures and photos of the devices in this issue that have been invented or © 2014 American Chemical Society
Jaan A. Pesti, Associate Editor
Special Issue: Continuous Processes 14 Published: November 21, 2014 1284
dx.doi.org/10.1021/op500323a | Org. Process Res. Dev. 2014, 18, 1284−1285
Organic Process Research & Development
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Editorial
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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REFERENCES
(1) Laird, T. Org. Process Res. Dev. 2013, 17, 1367.
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dx.doi.org/10.1021/op500323a | Org. Process Res. Dev. 2014, 18, 1284−1285
