Editorial: Solvent Choices and Sustainable Chemistry

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Abstract

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No easy solutions: Choosing a solvent for a certain reaction is not easy, and involves sustainability on many levels. The choice can be motivated by wanting to reduce or avoid wastes, reduce resource use, lower risks to humans and the environment, lessen energy use, or other ways of avoiding liabilities and costs. ChemSusChem wishes to promote thoughtful discussions on solvent use, and outlines in this Editorial basic guidelines for authors and referees.

Sustainability in chemistry and materials science can be interpreted in many different ways. In the bigger picture, every step towards processes that are cleaner and/or make better use of resources is beneficial. The growing influence of “sustainable thinking” on chemistry and materials science prompted ChemPubSoc Europe and Wiley-VCH to launch ChemSusChem in 2008, and the journal′s development since then follows from the increased prominence of the subject.

Choosing which solvents (if any!) to use for a certain reaction is a practical problem that involves sustainability on many levels. The choice can be motivated by wanting to reduce or avoid wastes, reduce resource use, lower risks to humans and the environment, lessen energy use, or other ways of avoiding liabilities and costs. And the choice of solvent is not only of academic interest: many publications in ChemSusChem result from close ties with research in chemical industry, where other factors than the best chemical performance can play a role. In addition, a solvent may be desirable because of certain properties, but banned because of other ones. All such considerations are weighed when taking a decision, and realistically a choice that is 100 % satisfactory might not be available.

However, the discussion, especially relevant in the area of sustainable chemistry, should be open and rational. ChemSusChem, together with other journals, considers itself among the leaders in the field and wishes to promote thoughtful discussions on solvent use. In cooperation with colleagues from the ACS Green Chemistry Institute (ACS GCI), more specifically the members of the Pharmaceutical Roundtable, we present recommendations that are intended to create awareness among authors and referees of the need to carefully consider and justify the use of solvents in manuscripts submitted to ChemSusChem.

Specifically, we ask of our authors the following:

• to avoid, if possible, the use of harmful solvents and replace these with less-harmful alternatives; • to rationalize the choice of solvent in manuscripts.

We ask of referees:

• to closely scrutinize the use of solvents as described in the Results and Discussion and Experimental paragraphs; • to ask for clarification and justification in case the choice of solvent is not commented on.

A complicating factor, of course, is that an all-or-nothing approach that bans some solvents and allows others is too blunt an instrument. Similar considerations outlined by other authors have recognized this, making use of the terms “preferred” and “undesirable” instead of simply “yes” or “no”. Examples are tables published by Alfonsi et al.1 and Laird.2 There may be cases where alternatives simply do not (yet) exist for the chemistry one wishes to perform. Here too, we ask that such cases are explicitly mentioned: a well-founded justification should be provided, describing that no alternative was available for the solvent used.

In short: authors of manuscripts submitted to ChemSusChem are expected to provide a clear justification for their choice of solvent. Manuscripts that do not provide such a rationalization may be rejected.

We are confident that you, the authors, referees, and readers, will support this policy. Based on past experience we are equally confident that for many of you this will cause either no or very little disruption to your research work, because most manuscripts we receive already give due consideration to solvents and methods. The use of solvents (and reagents) is a hot topic at the refereeing stage of many manuscripts. Rather than focusing only on how the outcome of research work contributes to sustainability, a general awareness that the end does not always justify the means is evident in numerous manuscripts and referee reports. This is not only expressed through discussions on solvent choices but also manifests itself in the increased use of metrics such as the atom economy or E-factor, and sophisticated evaluations such as life-cycle analyses.

The consideration of alternative solvents often leads to critical ways of looking at results: is it better to have a slightly lower yield if that avoids the use of solvent x? Is it acceptable that using a less-harmful solvent during synthesis slightly changes the properties of a material? By all means, do include such data in your results, tables, and figures. Discussions on the topics above are welcome in all manuscripts published in ChemSusChem, and we look towards authors and referees, and at a later stage towards readers, to engage in these discussions and share their experiences. And who knows: a referee or reader might be aware of a recent development that eluded the authors, and suggest an alternative during the peer-review process or shortly after publication. An ideal outcome would be that your chemistry works, or your material can be synthesized, in the same way in a “better” solvent.

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Guido M. Kemeling Editor-in-Chief ChemSusChem

Acknowledgements

Valuable input from R. Peoples (ACS GCI; currently at CARE), P. Dunn (Pfizer, Inc.; ACS GCI Pharmaceutical Roundtable), and J. Manley (ACS GCI), as well as several members of the Editorial Board, is acknowledged.

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