Introduction

The idea of green and sustainable chemistry gained worldwide attention following the publication of the famous book Green Chemistry: Theory and Practice by Paul Anastas and John Warner in 1998. After decades of industrial negligence, chemical accidents, toxic spills, acid rain, and tragic explosions, the new era of safer and more environmentally-friendly chemistry seemed about to begin. This new chemistry would help make the chemical industry more sustainable and introduce environmental concerns into the very heart of chemical syntheses. The OECD also launched its own initiative on “sustainable chemistry” in 1998, which brought together scholars from all over the world, including Paul Anastas and other chemists from the Environmental Protection Agency (EPA) who developed the green chemistry concept, to discuss its challenges and future lines of research (OECD 1999, p. 13). The flagship journal for the field, Green Chemistry, was founded in 1999 under the direction of James Clark from the University of York. In the following years, the number of articles inspired by the idea of the new chemistry exploded. A quick search in the Scopus database today yields tens of thousands of articles using the term “green chemistry” in their titles, abstracts, keywords, or in the names of the journals that publish them. Green Chemistry aside, journals such as Green Chemistry Letters and Reviews, Current Opinion in Green and Sustainable Chemistry, ChemSusChem, and many others were established to provide a platform for this new framework. The success of the concept of green chemistry appears unquestionable.Footnote 1

Unsurprisingly, the history of green chemistry has garnered substantial attention from scholars in history of science, science and technology studies (STS), and social sciences. These scholars have delved into topics such as greenness criteria, the identity of the discipline, and the epistemological foundations of the famous 12 principles of green chemistry. Some of these researchers have enthusiasticallt embraced the success story as told by the field’s leaders (Linthorst 2010; Llored and Sarrade 2016; Marques and Machado 2021), while others remained more reserved about the revolutionary claims of green chemists (Roberts 2006; Nieddu et al. 2014). One story, however, has remained under the radars of professional historians, even the critical ones, even though it challenges many assumptions about the standard success narrative presented above: the untold history of sustainable chemistry.

‘Wait, but aren’t green and sustainable chemistry the same thing’? Some would certainly argue that they are. The leaders of the field, including Paul Anastas, put it succinctly in 2016: “if Sustainability is the goal, Green Chemistry will show the way!” (Anastas et al. 2016) Another notable green chemistry specialist, Roger Sheldon, explained that: “One could say that sustainability is our ultimate common goal and green chemistry is the means of achieving it”, and the famous manual of environmental chemistry by Stanley Manahan simply stated “Green chemistry is sustainable chemistry” (Manahan 2017, p. 453). Many more scholars also use the terms interchangeably. Interestingly, the ultimate reference for the non-professional public, Wikipedia’s article on green chemistry, was modified on 23 November 2007, when a seemingly inconspicuous edit changed the beginning of the article from “green chemistry is…” to “green chemistry, also called sustainable chemistry, is…”.Footnote 2 Notably, this definition remained unchanged from 2007 until at least December 2022, and during the same period there was a redirecting link in Wikipedia from “sustainable chemistry” to “green chemistry,” effectively presenting both approaches as entirely equivalent.

If the two terms were interchangeable, this article would end here. Green chemistry would merely be a more fashionable name for sustainable chemistry; in fact, much more fashionable. The Scopus search returns around ten times more articles tagged as “green chemistry” than “sustainable chemistry”. However, things are not that simple. Timidly at first, some scholars began to use the term sustainable chemistry in a slightly more overarching way. Step by step, this line of thought developed throughout the 2000s. By the end of the 2010s, a full-blown alternative tradition crystallized, complete with its own institutions, reviews, and theoretical frameworks, especially, but not exclusively, in the German-speaking world. A 2021 paper by a group of sustainable chemistry scholars, led by a guru of the new tradition, Klaus Kümmerer, firmly states: “although GC [green chemistry] is an important building block for SC [Sustainable Chemistry], it is not necessarily sustainable, as GC does neither address possible implications of using renewable resources such as total substances, material, product and energy flows or alternative business models or catalysis trade-offs if metallic catalysts are used, nor ethics or stakeholder roles” (Zuin et al. 2021). Green chemistry is here reduced to a building block within the much more imposing edifice of sustainable chemistry. In a list of characteristics of sustainable chemistry also published in 2021, “green chemistry” is merely one out of ten traits (Kümmerer et al. 2021).

Which is it then? Are green and sustainable chemistries the same, or are they two separate traditions? How is it possible that scientists disagree over this question to such an extent? The purpose of this article is to explore the untold story of sustainable chemistry, understood as a concept separate from green chemistry. The overarching ambition of the paper is to highlight the complex trajectory of certain concepts and expressions and how the meaning of terms can evolve in a very short time. The article traces the evolution of narratives that led to the rise of sustainable chemistry and shows that while the two framework (green and sustainable chemistry) were overlapping in the late 1990s, they slowly grew apart especially after the 2010s, largely due to the developments within the German-speaking world. The paper’s main argument is that there is nothing inevitable in the emergence of new disciplines, schools of thought, and paradigms. Not only are they historically contingent, but the diversity of languages used to describe scientific problems can foster new original lines of investigation. In other words, linguistic boundaries can provide a “safe space” in which ideas can hatch before flourishing in the global community.

Before proceeding, one preliminary methodological and terminological challenge needs to be addressed. The history of subdisciplines of chemistry is a fertile topic that has generated a wide range of studies over the last decades (Servos 1990; Bensaude-Vincent 2001; Teissier 2014; Krasnodębski 2018). It might be tempting to include this paper, as well as articles on the history green chemistry mentioned above, as part of the same trajectory. After all, green chemistry exhibits several characteristics of a discipline: its own journals, institutions, and a (sort of) theoretical framework. And yet, the initial ambition of green chemistry forerunners was not to create a new discipline but to transform the entire practice of chemistry. This problem was explored already in 2006 by Jody Roberts, who chose to frame green chemistry as a “movement”, rather than a discipline (Roberts 2006). But today, considering the amazing popularity of the green chemistry vocabulary, it is hard to see it as a single movement. It has become more of a bundle of ideas transcending different disciplinary communities. Suffice to say that green chemistry is not strictly speaking a discipline, but a broader epistemological category (using the word “paradigm” might be tempting, but I am hesitant to adopt it for all the Kuhnian connotation it carries).

What matters for the sake of this paper is that green chemistry, in spite of its fluid boundaries, has been most often understood as, above all, green synthesis: an attempt to reduce environmental impact through the redesign of chemical products and processes. However, many critics found this approach overly restrictive and suggested that a more comprehensive understanding of the process of greening chemistry and of the chemical industry was necessary; some framed this extension as sustainable chemistry (others, recently, as one-world or circular chemistry, see: Krasnodębski 2022-2). As a consequence, all the discussion on the boundaries of the concept of green chemistry applies, per analogiam, to the emerging concept of sustainable chemistry as well, perhaps even to a larger degree.

As such, this paper’s goal is not to venture into the epistemological debates over the status of green/sustainable chemistry as a (proto/meta)discipline and it refers to both as “traditions”. It focuses on a specific narrow trajectory instead, providing an empirical foundation that may be a starting point for historians of science to penetrate the history of sustainability sciences with a more informed perspective.Footnote 3

1. OECD workshop and first controversies

The first high-profile publication with the name “sustainable chemistry” in its title and with some theoretical framework outlining the concept was the OECD report summarizing the discussions during a sustainable chemistry workshop held in 1998, the same year the seminal book by Anastas and Warner came out. The report offered us the first tentative definition of this new field in its introduction:

“Within the broad framework of sustainable development, one should strive to maximise resource efficiency through activities such as energy and non-renewable resource conservation, risk minimisation, pollution prevention, minimisation of waste at all stages of a product’s life-cycle, and the development of products that are durable and can be re-used and recycled. Sustainable Chemistry strives to accomplish these ends through the design, manufacture and use of efficient and effective, more environmentally benign chemical products and processes” (OECD 1999, p. 13).

Elsewhere in the same volume, a narrower definition was also formulated: “Sustainable Chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances” (Carra 1999, p. 48). Readers familiar with green chemistry may realize that the second definition is almost identical to definitions of green chemistry developed by the EPA throughout the 1990s. I will not discuss the early history of green chemistry here, as there is an abundance of literature on the topic (Woodhouse and Breyman 2005; Linthorst 2010; Roberts 2006), but it is key to explain that green chemistry was initially defined as the art of incorporating environmental considerations into the very design of the reactions, molecules, and processes in order to avoid toxic waste and pollution. Anastas and Warner codified green chemistry into 12 principles that became almost synonymous with the concept, and conquered the imagination of environmentally-minded chemists all over the world (Table 1).

Table 1 12 Principles of Green Chemistry (titles according to the ACS)Footnote

12 Principles of Green Chemistry accordint to the American Chemical Society. <https://www.acs.org/content/acs/en/greenchemistry/principles/12-principles-of-green-chemistry.html>

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Already at this stage, we see a slight discrepancy between the two definitions of sustainable chemistry presented above. While the first definition includes pollution prevention, it also mentions recycling and life-cycle assessment, which go somewhat beyond a narrowly construed green chemistry (according to the 12 principles). The second definition aligns strictly with the EPA’s narrower green chemistry ambition. These were, however, minor differences and the contributors to the volume did not seem to explore them any further. The author of the second definition, an EPA employee Joseph Carra, explicitly stated in his chapter that green and sustainable chemistry were two names for the same concept, one used in the US, the other by the OECD, but there was no substantial difference between them (Carra 1999). In fact, out of 25 papers published in the OECD book, eleven had “sustainable chemistry” in their titles, and five “green chemistry”. The five green chemistry papers were all produced by American scholars, including Anastas, Warner, and the Director of the Green Chemistry Institute, Joseph Breen. Of the papers using the term “sustainable chemistry”, five were written by researchers from Japan, five from Germany and Austria, and one was the article already mentioned by Carra, for whom the two concepts were identical. One of the Japanese papers also reiterated that both terms essentially meant the same thing (Ida 1999). In other words, it appears that the difference in the choice of wording ran across national, rather than conceptual, lines. In this sense, the workshop can be said to confirm the narrative according to which there is no difference between green and sustainable chemistries.

What the official OECD publication does not relate, however, are all the tumultuous debates that galvanized participants during the conference itself, and that we can only reconstruct based on various comments that appeared in the press over the period. For instance, a Canadian scholar, Ian Brindle, described in one of the 1999 editorials of the Green Chemistry journal a discussion that took place during the OECD’s meeting on sustainable chemistry:

“Problems arose from the difficulties that the delegates had trying to incorporate the perspective of the Brundtland Report on sustainability into the already established notion of green chemistry. The idea of sustainable chemistry creates a new set of problems. Green chemistry […], in my view, remains a better descriptor than sustainable chemistry. Extraction of non-renewable resources is, by its nature, not sustainable and so the notion of doing sustainable things with an unsustainable end sounds perverse” (Brindle 1999).

What did Brindle mean? His comments referred to the problem of applying green chemistry principles to mining-related operations. In his view, the objective was to “green” these activities, but since this chemistry concerned non-renewable feedstock (minerals coming from mining), it could not be called sustainable. Brindle highlighted the fact that there was no real consensus over the matter, and green chemistry had many advocates who considered the concept of sustainable chemistry misleading.

The dispute regarding the preference for one wording over the other divided international organizations such as the IUPAC (International Union of Pure and Applied Chemistry). One of the early programmatic papers on green chemistry, co-authored by Anastas in 2000, and stemming from the work of the IUPAC Working Party on Synthetic Pathways and Processes in Green Chemistry, explains the problem in the following terms:

“The terminology ‘green chemistry’ or ‘sustainable chemistry’ is the subject of debate. The expressions are intended to convey the same or very similar meanings, but each has its supporters and detractors, since ‘green’ is vividly evocative but may assume an unintended political connotation, whereas ‘sustainable’ can be paraphrased as ‘chemistry for a sustainable environment’, and may be perceived as a less focused and less incisive description of the discipline. Other terms have been proposed, such as ‘chemistry for the environment’ but this juxtaposition of keywords already embraces many diversified fields involving the environment, and does not capture the economic and social implications of sustainability. The Working Party decided to adopt the term green chemistry for the purpose of this overview. This decision does not imply official IUPAC endorsement for the choice. In fact, the IUPAC Committee on Chemistry and Industry (COCI) favors, and will continue to use sustainable chemistry to describe the discipline” (Tundo et al. 2000).

In other words, even in a single organization different vocabularies competed one with each other. While the Americans, supported by the EPA and the Green Chemistry Institute, hampioned the concept of “green chemistry”, it was the Germans who spearheaded the oppoition and advocated for “sustainable chemistry”. It appears that internal German politics was the reason for this conflict.

German green exceptionalism

Professor Otto Hutzinger from the University of Bayreuth explained the problem in 1999 in the following way:

“Whilst most scientists use English as the lingua franca of science, some argue that cultural-sociological factors giving different meanings to terms and words should also be considered. ‘Green’, for instance, in a cultural context simply means something different in countries such as the U.S. and Germany. (…)

In Germany, the term ‘green’ in many elicits political-sociological feelings - for instance, fear of production shutdowns in chemical industry - and general opposition to genetic engineering projects and atomic energy by members of the Green Party.

There has been strong opposition against the term ‘green chemistry’ by IUPAC, OECD, CEFIC and GDCh headed by the German speaking members. Further, ‘green’ was abandoned by the European Commission in the section of the 5th Framework program, likewise headed by the German speaking members.

The underlying meaning of the terms ‘Green Chemistry’ and ‘Sustainable Chemistry’ is different. Sustainable Chemistry is the maintenance and continuation of an ecologically sound development whereas Green Chemistry focuses on the design, manufacture, and use of chemicals and chemical processes that have little or no pollution potential or environmental risk and are both economically and technologically feasible. The principles of green chemistry can be applied to all areas of chemistry including synthesis, catalysis, reaction conditions, separations, analysis, and monitoring. Thus, the terms cannot easily be exchanged” (Hutzinger 1999).

There is a lot to unpack here. First, the opposition to the term “green” in Germany was, according to the author, driven by the political connection of the word with the activism of the German Green Party (Bündnis 90/Die Grünen), which has traditionally been highly critical towards the chemical (and nuclear) industry in general. The terminology and the metaphors of green chemistry may have been too close to the discredited concept of soft chemistry (sanfte Chemie) sponsored by the Green Party, which had elicited fears among the German industrial establishment already in the early 1990s (Fischer 1993). Second, Hutzinger mentions in the paper that the representatives of German industry holding prominent positions in the international bodies (OECD, IUPAC etc.) actively fought against their Anglo-Saxon colleagues to keep the green vocabulary from spreading. In fact, Hutzinger refers to debates concerning the naming of the European Green Chemistry Award, which subsequently became the European Green and Sustainable Chemistry Award, due to the pressure of the German chemists. Finally, Hutzinger concedes that green and sustainable chemistry are two different things. In his view, green chemistry was much more meaningful and narrower. This is not surprising. By 1999, the theoretical backbone of the green chemistry concept had been already established by the EPA. In contrast, the idea of sustainable chemistry remained somewhat elusive, tentatively defined in various contexts, and relied heavily on intuition.

Overall, the result of the opposition by the German industry was that the German word of choice to describe the environmentally-friendly chemistry was “nachhaltige Chemie” (sustainable chemistry) and not “grüne Chemie” (green chemistry). In fact, the German federal government was already using the concept of nachhaltige Chemie in its internal documents in 1997 to describe the lines along which German industry should develop (Weise et al. 1999).

It is important to note that in German-speaking publications, the concept of nachhaltige Chemie continued to be widely used throughout the 2000 and 2010s, while in English the green vocabulary clearly dominated the discourse. Figures 1 and 2 present Google Ngram plots illustrating the scale of the discrepancy between the terminology in both linguistic zones.

Fig. 1
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Popularity of “sustainable chemistry” and “green chemistry” according to Google Ngram (English-speaking books)

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Fig. 2
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Popularity of “nachhaltige Chemie” (sustainable chemistry), and “grüne Chemie” (green chemistry) according to Google Ngram (German-speaking books)

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In the English literature, the green chemistry concept has undoubtedly been the basic frame of reference, while the term sustainable chemistry has remained largely marginal. In Germany, however, nachhaltige Chemie appears to be overall dominant, even though the preference weakened in the 2010s. This must be nuanced though. The Germans were so reluctant to talk about grüne Chemie for political reasons that they used the English term “green chemistry” in German-language publications instead. Even today, when the opposition to the word “grün” appears to have waned, some German-speaking articles still prefer the English terminology.Footnote 5 If we analyze German books digitized by Google and combine the terms “grüne Chemie” and “green chemistry” into a single category, the advantage of sustainable chemistry is slightly less pronounced, although it is still much more popular than in English (Fig. 3). As a side-note: the French rapidly adopted the “chimie verte” (green chemistry) terminology and the term “chimie durable” (sustainable chemistry) remains in general on the periphery of the discussions, largely reflecting the patterns observed in the English literature.

Fig. 3
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Popularity of “nachhaltige Chemie” [sustainable chemistry] and of the combined category of “green chemistry” + “grüne Chemie” according to Google Ngram (German-speaking books)

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The uniqueness of the German case can be attributed to several factors. The most direct reason is the already mentioned opposition of the chemical industry to the green political and social movements, but other potential explanations should not be neglected. For example, it was in Germany that the term sustainability (Nachhaltigkeit) originated in the context of forestry back in the eighteenth century (Pufé 2017, p. 37). This longstanding Nachhaltigkeit tradition, although limited to forestry for decades, may have legitimized the nachhaltige Chemie wording, making it familiar to a German reader. Another indirect reason to reject the “green chemistry” vocabulary was that there had been already different traditions in Germany dealing with similar challenges. Let us consider three of them.

First, there existed a specific German academic tradition of ökologische Chemie (ecological chemistry) created by Professor Friedhelm Korte in the 1970s. The story goes that unlike Umweltchemie (environmental chemistry), which studied chemical processes in the environment in general, ökologische Chemie was much more focused on human influence and pollution in the environment, particularly emphasizing ecotoxicology from a chemical perspective (Böschen et al. 2003). In other words, it encompassed many ideas that would be later formalized by the fields of green or sustainable chemistry.

Second, another far-reaching and somewhat radical tradition was sanfte Chemie (gentle/soft chemistry). It was developed in the 1980s by scholars affiliated with the German green movement, such as biologist Arnim von Gleich and chemist Herman Fischer (Gleich 1989; Fischer 1993). Sanfte Chemie’s revolutionary claims involved a complete phasing out of non-renewables, biomimetism, using nature as the inspiration for chemical processes, and the development of a new ethical way of thinking about interactions with inanimate matter. While this chemistry raised concerns of the German chemical industry because of some of its radical claimsFootnote 6, it is worth noting that some of its pleas foreshadowed at least some recent developments in modern green/sustainable chemistry such as the utilization of plants for chemical synthesis and the integration of life-cycle assessment in innovation processes.

Finally, the German chemical industry itself made efforts to mitigate toxic pollution and developed theoretical foundations for a new way of thinking about these problems. The most ambitious conceptualization came from Claus Christ, who formulated the concept of “Production-Integrated Environmental Protection and Waste Management in the Chemical Industry” throughout the 1990s, with its own set of codified rules (Christ 1999). Christ’s rules shared similarities with the 12 principles of green chemistry, but it appears that their author was not familiar with the American concept back in 1999 and his list was based on an autonomous pollution prevention philosophy that had gradually developed within the German industry since the 1970s.

All three disciplinary frameworks mentioned above (rooted in academia, the world of politics, and industry respectively) warrant greater attention from historians of green and sustainable chemistry, but what matters for now is that when American green chemistry arrived in Germany, it was merely another concept trying to frame debates that had been going on for decades in the German-speaking world. German chemists did not necessarily perceive it as something particularly revolutionary, and thus may have been more reluctant to embrace it, especially because it lacked some of the more overarching features of native concepts such as ökologische Chemie and sanfte Chemie, or had little added-value compared to Claus Christ’s conceptualization. German chemists simply did not need the well-defined and somewhat rigid American green chemistry to frame environmental debates. Due to its name, they preferred to avoid it and appeal to their own domestic traditions. Sustainable chemistry, a term that covered roughly similar ideas and was internationally recognized, but was, at the same time, broader, less defined, and more ecumenical than green chemistry, could count on a warmer reception in Germany. In the following years, a tremendous amount of conceptual work on what sustainable chemistry is and what it should be was conducted by German-speaking chemists and developed in German- and Austrian-based institutions.

Paving the way for an alternative: sustainable chemistry in the 2000s

The mere fact that the German speakers used a different name does not automatically mean that the content of the term also differed. The boundaries of both sustainable and green chemistry were not set in stone back in the early 2000s, and for many stakeholders, in German-speaking countries included, both concepts remained either identical or at least very similar. The difference in the wording, however, encouraged thought experiments and reflection on possible differences. One of the first comprehensive definitions of sustainable chemistry, understood as something explicitly different than green chemistry, came from a group of German scholars led by a scientist-turned-sociologist Stefan Böschen in 2003, in an article published in English:

“Here we propose a working definition of sustainable chemistry which comprises two elements: (1) at the level of energy and material flows, the aim of sustainable chemistry is to optimise processes and products with respect to resource consumption, waste generation and properties of products (low toxicity, efficiency, degradability etc.); (2) with respect to the interaction with non-scientific actors, the aim is to reconcile and coordinate scientific objectives with non-scientific demands, preferences and values; to this end, it is necessary to make transparent the assumptions as well as objectives and implications of scientific research” (Böschen et al. 2003).

The article talks about the EPA’s green chemistry, understood mostly as environmentally benign synthesis, and presents it as one of the tools for achieving the goals of a much more ambitious project of sustainable chemistry. This sustainable chemistry would incorporate green synthesis, the renewability of feedstocks, and life-cycle assessment, but especially openness to social dialogue. It would be a chemistry responsive to the needs of society. Böschen makes part of a different intellectual tradition than many green chemists and cites mostly German papers, including the works of the already mentioned founder of sanfte Chemie, Arnim von Gleich, as well as the pioneer of ökologische Chemie, Friedhelm Korte.

It is important to consider the details carefully though. In terms of overall ambitions, Böschen’s paper does not radically differ from what was discussed over the same period in the US. For example, the 2006 American National Research Council report Sustainability in the Chemical Industry, Grand Challenges and Research Needs, enumerated “green and sustainable chemistry and engineering” alongside life cycle analysis, renewability, toxicology, and sustainability education, as grand challenges of sustainability (National Research Council 2006). American green chemists were also fully aware of the importance of social dialogue and engagement. What is different is that for the Americans, in the middle of the 2000s, there was green chemistry (understood as environmentally friendly synthesis), and there were these other important tools or ideas for achieving sustainability. For Böschen, on the other hand, they all were part of a single grand project labeled as sustainable chemistry. In other words, the overall goals were identical, but the framing of the debate was slightly different.

As interesting as these subtleties are, none of this warrants the creation of an a genuine alternative to green chemistry. German scholars simply participated in a very vivid discussion about transforming and making chemistry more environmentally friendly, and their ideas were only some of many. Certainly, the 2003 paper should not be regarded as foundational in any meaningful manner, and certainly not in the sense the EPA’s green chemistry books and papers had been in the 1990s.

One year after Böschen’s article, in 2004, an international congress took place in Dessau, Germany under the title “Sustainable Chemistry – Integrated Management of Chemicals, Products and Processes”. It was jointly organized by the OECD and by the German Federal Ministry of the Environment, Nature Conservation and Nuclear Safety. The conference served as a continuation of discussions initiated during a previous conference held in 2002 in Johannesburg, where the topic of sustainable chemicals and processes had been already adressed (Steinhäuser et al. 2004). The 2004 event did not propose any form of definition regarding what sustainable chemistry should look like, but the scope of the presentations clearly indicated that it was more than just green chemistry, or at least that the concepts were not equivalent (even though Paul Anastas was a keynote speaker). For example, the papers presented during the congress brought up problems with the regulation of toxic chemicals, consumer information, and chemical leasing. Chemical leasing is certainly a topic that warrants discussion in the context of making the chemical industry more sustainable, but it goes beyond narrowly construed green chemistry.

Two years later, in 2006, the book Nachhaltige Chemie. Erfahrungen und Perspektiven [Sustainable Chemistry: Experiences and Perspectives] pushed the development of the field along the lines of the 2004 congress. It was a collection of chapters on various topics connecting sustainability and chemistry, and it was probably the first full-blown textbook with sustainable chemistry in its title ever published (Angrick et al. 2006). None of the chapters privided any well-articulated definition of sustainable chemistry. In fact, in its first chapter, written in English by a British scholar Jeff Hardy and titled “The Politics and Practice of Sustainable Chemistry in the UK”, the author refers freely to green chemistry as a synonym for sustainable chemistry. The German authors in the following chapters are also relatively liberal when it comes to definitions and frequently mention the 12 principles and the EPA’s contributions to the field. What makes the book interesting, however, is its scope, which extends far beyond the rational green design of molecules and includes topics such as white biotechnology, biomimetism, and organizational solutions such as chemical leasing that go far beyond the 12 principles. The publication laid the groundwork for further discussions, even though the book’s contributors were still somewhat reluctant to assert that sustainable chemistry should be a fully-fledged discipline or a new chemical paradigm on its own.

This was also the case with the journal ChemSusChem, established in 2008, which was arguably the first journal in sustainable chemistry (and not just green chemistry). Its thematic scope atthe time included topics traditionally associated with green chemistry (e.g. catalysis for pollution prevention), topics whose onnection to green chemistry is somewhat ambiguous (e.g. biomass, biofuels, renewability), and topics that are clearly outside green chemistry’s scope (e.g. photovoltaics, CO2 capture). While ChemSusChem did not develop or present any coherent sustainable chemistry framework in its pages, one of its founders explained that the establishment of the journal had been preceded by discussions “about the necessity for a journal focusing on chemical aspects of sustainability. Sustainability is more than being green!” (Smith 2021). It appears that there was a vague feeling that something had been left out by green chemistry so far. Again, the shift towards the sustainability vocabulary can also be explained by the fact that ChemSusChem was owned by the European Union of Chemical Societies, and that the editorial team was based in Germany and associated with Angewandte Chemie’s family of journals.

In the late 2000s, more and more works openly differentiated between sustainable and green chemistry. For example, the book Sustainable Industrial Processes from 2009 included a chapter titled “Green versus Sustainable Chemistry” in which the authors cited the distinction between the two made by Hutzinger in 1999, and then noted: “We could add that sustainable chemistry is not synonymous with green chemistry, (…) [it has] a lower impact on environment and human health, but goes beyond the latter concepts, seeing chemistry as part of an integrated vision where chemistry, sustainability and innovation are three key components for the future of our society” (Centi and Perathoner 2009, p. 5). Overall, however, the book incorporated much of the scholarship in green chemistry and the differentiation between the two was not articulated in its various chapters.

In 2011, another book titled Sustainable Chemistry was published, as a follow-up to the “First International Conference on Sustainable Chemistry” co-organized by the Wessex Institute of Technology and the University of Antwerp. The conference included six sections: eco-efficiency, smart processing technology for sustainability, improvements in catalysis, multifunctional materials, bio-based materials, and environmental health issues. While some of these topics, especially catalysis, but also, to some extent, bio-based materials, overlap with green chemistry as traditionally construed, the others again steer in a very different direction. Perhaps the most telling example is the introductory chapter co-authored by G. L. L. Reniers, an economist and one of the volume’s editors. The chapter “How to enhance sustainable chemistry in a non-technological way?” explains that:

“To achieve sustainable industrial chemical processes and products, companies, research centers and academia tend to focus mainly on technological solutions such as cleantech, green technology, process intensification, new catalysts, new membranes, ecofining, etc. However, non-technological approaches are essential as well to succeed in adequate sustainable chemistry. Cluster management, sustainable supply chain management, chemical leasing, integrated management systems and business models, societal expectations, etc. are all important non-technological aspects of sustainable chemistry” (Reniers and Brebbia 2011, p. 3).

Sustainable chemistry was slowly taking shape as something genuinely different and more socially oriented than green chemistry in a more and more formalized way.

Separating sustainable from green (2011–2021)

Some of the most important developments when it comes to the term sustainable chemistry in the second decade of the 21st century concern the establishment of three journals. The first was the American Chemical Society’s Sustainable Chemistry and Engineering (established in 2013). The journal’s first editorial did not suggest that it was conceptually any different from other green chemistry journals. On the contrary, it stated that: “This first issue is the culmination of several years of planning within the American Chemical Society for a journal dedicated to publishing high impact research advances in the fields of green chemistry, green engineering, and sustainability.” (Allen et al. 2020, p. 1) Was the ACS’s journal just another review of green chemistry which used the name “sustainable chemistry” to distinguish itself from the reviews already on the market? The first issue included topics such as biomass, solvents, and green metrics. None of these would suggest that the notion of sustainable chemistry is understood in any larger way than green chemistry. Yet, when we analyze the journal’s editorials throughout the years, we see the broadening of the scope. In 2020, an editorial explains that ACS Sustainable Chemistry and Engineering is a forum for:

“authors and readers working in areas of (I) catalysts for sustainable chemical transformations, (ii) renewable materials, (iii) electrochemistry, photochemistry, and photoelectrochemistry for energy conversion, energy storage, and synthesis of value added chemicals, (iv) benign solvents, (v) biorenewable feedstocks in fuel and chemical manufacturing, (vi) sustainable chemical synthesis, (vii) design of sustainable chemical processes, (viii) industrial ecology and sustainable chemicals management, and (ix) the use of advanced nanomaterials for sustainable chemistry/engineering applications” (Allen et al. 2020).

There is a certain overlap with traditional topics in green chemistry, but also some largely different lines of research normally associated with the broader environmental community (e.g. energy storage, industrial ecology, sustainable chemicals management). This inclusive approach may be interpreted in two ways. On the one hand, it may be seen as the realization that green chemistry is too narrow in scope, and the expansion observed above is a step towards constructing a more overarching perspective of sustainable chemistry. On the other hand, if we consider green and sustainable chemistry to be basically the same thing, the shift can be seen as a natural evolution of green chemistry to incorporate more diverse topics. However, the same evolution is nowhere to be found in the flagship Green Chemistry that remained more circumscribed in its publication philosophy, suggesting that ACS Sustainable Chemistry and Engineering follows its own more inclusive path.

Two other important journals from the period are Sustainable Chemistry and Pharmacy and especially the Current Opinion in Green and Sustainable Chemistry, both co-created by Klaus Kümmerer, a leading figure in the field and probably the most active promoter of sustainable chemistry today, who was also in contact with the sanfte Chemie group in the 1990s. The inaugural issue of Current Opinion from 2016 was a follow-up to the “1st Green and Sustainable Chemistry Conference” hosted in 2016 in Berlin (note that the 1st Conference of Sustainable Chemistry that took place in Antwerp in 2011 did not seem to have been continued). The choice of wording in this first issue was accommodating. The editors integrated green and sustainable chemistry into a single discipline, or at least highlighted the compatibility of the two approaches. However, when upon analyzing the content of the journal, we see a distinct approach. The originality is particularly striking if we look at the papers from the second Green and Sustainable Chemistry conference in 2018, published in the journal’s pages (Table 2).Footnote 7

Table 2 Selected Papers from the 2nd Green and Sustainable Chemistry conference published in Current Opinion in Green and Sustainable Chemistry in 2018
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The challenges of the circular economy, social problems with education regarding plastics and pollution, the study of the sustainable material flow necessary for the establishment of a manned Moonbase, and much discussion about plants and biomass; virtually none of these touch upon the classic topics of green chemistry found in the EPA green chemistry conferences in the 1990s and in the 1998 seminal book by Anastas and Warner. The disparity is not a result of knowledge advancement, but rather the framing of the problems under consideration. While some articles published in this journal’s pages could well appear in Green Chemistry, the emphasis is definitely elsewhere.

The slow rise in the popularity of the “sustainable chemistry” term led to an interesting situation in which some scholars started using the combined term “green and sustainable chemistry” or even simply “sustainable green chemistry” in the second half of the 2010s without trying to delineate the two concepts from a theoretical standpoint at all (Burgman et al. 2018; Champagne and Matharu 2016). This may be perfectly justifiable in many cases, however, many other scholars underlined often the distinct theoretical underpinnings of the two concepts. This was the case for Klaus Kümmerer and James Clark (creator of the Green Chemistry journal), who wrote a chapter together in 2016 titled “Green and Sustainable Chemistry” for a textbook in sustainability science. These two leading scholars explained that “Sustainable chemistry includes economical, social and other aspects related to manufacturing and application of chemicals and products. It aims not only at green synthesis or manufacturing of chemical products but also includes the contribution of such products to sustainability itself” (Kümmerer and Clark 2016, p. 46). The publication portrays green chemistry as a subset within a much broader concept of sustainable chemistry. If Clark, one of the founders of the entire green chemistry movement, fully embraced the differentiation between the two ways of thinking about, it clearly indicates that a shift was under way.

Another paper, from 2017, published in the pages of Green Chemistry by a group of French scholars, put even more effort into delineating the two concepts. Titled “Sustainable chemistry: how to produce better and more from less?” it explained that: “If green chemistry and sustainable chemistry are often considered as synonyms, it is clear that differences of meaning do exist” (Marion et al. 2017). For the French researchers:

“Sustainable chemistry can be defined as the development of an even safer and more environmentally-friendly chemistry but one which also equally integrates the priorities of economic competitiveness and societal concerns. Sustainable chemistry is a complex equation which must ensure the longevity of the human, animal, and vegetable species whilst taking into consideration issues related to accessing different resources (carbon, water, metals), problems of access to energy, global warming, the exponential increase in the human population, for which chemistry must allow a serene development, the social and environmental impact of the value chain, and the erosion of biodiversity, while of course maintaining economic competitiveness to create profit and business.”

This is a fantastically comprehensive definition, succinctly summarizing many of the concerns that have been expressed in a less concise way elsewhere. The insistence on global warming and biodiversity is to be particularly noted, as such broad considerations were never part of (mainstream) green chemistry.

Not only did sustainable chemistry become more and more systematized, but it also developed its own post facto generated genealogies that tried to give the concept more historical legitimacy. One such attempt was published in 2021 (one of the co-authors was Kümmerer). The article presents a short history of both green and sustainable chemistry. Regarding green chemistry, it reproduces the traditional narrative, with the EPA scientists being presented as key actors in the formation of the discipline, and with a special emphasis on the famous 12 principles. However, the article places the birth of sustainable chemistry in the early 1990s in the German Chemical Society. The article says that: “This approach was motivated by a broader view from the environment, i.e., end of products’ life side, not from the synthesis side mainly” (Zuin et al. 2021). There were certainly discussions over the life-cycle assessment of chemical products led in many national and international institutions in the early 1990s, so this statement is not wrong per se (although there is nothing that warrants the idea that the Germans discussed it more thoroughly than the Americans or anyone else), but it must be made clear that nothing remotely similar to the formalization of green chemistry principles took place in Germany in the context of sustainable chemistry. As already explained, there was Christ’s “Production-Integrated Environmental Protection”, but it was very much focused on synthesis mirroring green chemistry’s objectives, and there was sanfte Chemie, which was certainly very ambitious but remained outside mainstream science. Nachhaltige Chemie, if ever used, was a very intuitive concept, so comparing it with green chemistry over the period is misleading. Later, the authors of the 2021 paper mentioned the OECD definition of sustainable chemistry from the late 1990s as another pivotal milestone in the development of the new concept. Again, while not strictly speaking false, it has to be reiterated that this definition was in agreement with the EPA’s green chemistry and the majority of the participants at the OECD seminar did not differentiate the two at all.

Just as the official history of green chemistry has been smoothed down by conveniently forgetting about the conceptual struggles of the 1990s and placing the founding date somewhat arbitrarily in 1991Footnote 8, the reconstruction of the history of sustainable chemistry in the 2021 paper serves a similar purpose. It seeks to portray sustainable chemistry as a tradition as old and venerable as green chemistry, in order to build its own separate identity and justify its autonomy. The problem is that this reconstruction rests on precarious grounds. While sustainable chemistry has emerged organically over the last three decades, it was not until very recently (the late 2010s) that it acquired anything resembling a theoretical framework, very unlike the EPA’s green chemistry that can be clearly traced to the 1990s, and whose own theoretical foundation was fully laid out in 1998.

Overall, the 2021 article’s purpose was to show the superiority of the new concept and to point out the flaws in the American green tradition: “it is not clear how many of the 12 GC [green chemistry] principles have to be met and how ‘ambitious’ it has to be to call a chemical ‘green’ or ‘greener’ compared to another one” (Zuin et al. 2021). This is a harsh criticism to appear in a journal whose name is Green Chemistry, but it perhaps shows that, at least among some scholars in the field, the problems of greenness are more and obvious, and the idea of sustainable chemistry offers a welcome shift in focus.

Formalizing sustainable chemistry

Sustainable chemistry emerged as an attempt to address the insufficiencies of green chemistry, but fleshing out a concept is not enough to attract international attention and obtain new acolytes. What is needed are: (1) an institution (such as the Green Chemistry Institute in the US), (2) a manifesto (similar to Anastas and Warner’s 1998 book), and, in particular, (3) some sort of catchy code of conduct or summary of concepts equivalent to the 12 principles.

As for the institution, it has been created in Germany in 2015 as a fruit of collaboration between the Umweltbundesamt (the German Federal Environmental Agency, roughly an equivalent of the EPA in the US) and the German Ministry of the Environment. The new International Sustainable Chemistry Collaborative Centre (ISC3) became a leading German institution promoting sustainable solutions in the chemical industry. Its ambitions can be compared to those of the American Green Chemistry Institute created in 1997. ISC3 organizes events and seminars, funds research, and above all provides a platform for scholars interested in the challenges of sustainability in chemistry.Footnote 9 Of course, there are many institutions, centers, laboratories, and other entities that claim to practice sustainable chemistry. There are also many that practice green chemistry, other than the Green Chemistry Institute, but the Green Chemistry Institute is not like the others. Led by Anastas and his collaborators, it argued for a specific understanding of what green chemistry should be and promoted the famous 12 principles. The ISC3 is similar in this respect, it does not simply work on topics that could qualify as sustainable chemistry, but its members, including Klaus Kümmerer, also actively work on improving and promoting sustainable chemistry as a separate framework.

As for a manifesto, there were a few attempts to construct it, often coming from researchers connected (more or less formally) to the ISC3, or published in the pages of the journals founded by Kümmerer. One of the most comprehensive overviews of the field’s aspirations, fully and exclusively devoted to the definition of the concept, was presented in a German-language article titled “Das Konzept der Nachhaltigen Chemie: Schlüsselfaktoren für den Übergang zu einer nachhaltigen Entwicklung” [The Concept of Sustainable Chemistry: Key Factors for the Transition to Sustainable Development] published in the pages of Sustainable Chemistry and Pharmacy in 2019. It offers the following definition:

“Sustainable chemistry contributes to the positive, long-term development of the society, the environment and the economy. With new approaches and technologies, it creates attractive products and services to answer the needs of the civil society. Sustainable chemistry increasingly uses substances, materials and processes that have possibly the smallest harmful effects, it uses substitutes, alternative processes and recycling concepts and conserves natural resources. It prevents damage and impairment to people, ecosystems, and resources. Sustainable chemistry is based on a holistic approach and sets measurable goals for a continuous change process. Scientific research and education for sustainable development in schools and vocational training are an important basis for it” (Blum et al. 2019, my translation).

The paper strongly aligns with the existing literature on sustainability. This is one of the important differences between sustainable and green chemistry theoretical papers. The authors who advocate for sustainable chemistry usually focus on the broad trajectory of sustainability and draw on OECD or UN documents, conferences, and summits as the formative moments for their work. Green chemistry proponents are usually much more EPA-centric in their descriptions of the history of the field.

This does not mean that the authors of the aforementioned paper overlooked the contributions of green chemistry. On the contrary, they incorporated the notion of green chemistry into their definitions and acknowledged its importance for their project, but they also reiterated numerous times that sustainable chemistry was broader than green chemistry, and that the two should not be conflated. Green chemistry was only one of many “key elements for sustainable chemistry” (it is important to note that, in the typical German manner, the authors often referred to green chemistry in English instead of using the German equivalent “grüne Chemie”). While the article offers valuable contributions to the understanding of the challenges of the new emerging paradigm, issues arise, however, when it attempts to define seven goals and guiding principles for sustainable chemistry which were meant to compete with the 12 principles of green chemistry (Table 3).

Table 3 Seven guiding principles for sustainable chemistry
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This list of goals, while programmatic and outlining the core elements of the concept in a concise manner, is somewhat ambiguous if we compare it to the 12 principles of green chemistry. In fact, sustainable chemistry principles 1, 2, and, to an extent, 3 and 4, can be easily interpreted from the principles of Anastas and Warner (Table 1). The emphasis is elsewhere and the message is clearer, but there is little added value. While sustainable chemistry principles 6 and 7 were not directly formulated in the 1998 book, Anastas, Warner, and their collaborators often underlined the importance of economic viability for the success of green chemistry many times, as well as the fact that green chemistry has to be promoted and adopted on a voluntary basis by the industry (Roberts 2006). These two were the “unwritten” principles of green chemistry, so their formalization may be helpful, but they do not differentiate green from sustainable in any meaningful manner. The only fully new principle (5), as compared with the 12 principles of green chemistry, concerns recycling, but even this principle was implied for many scholars in the field and is hardly novel in any way. Overall, these seven principles bring little to the table for practitioners of chemistry compared with green chemistry. This does not mean that the entire concept as presented in the German article is not different from that of green chemistry, or that it does not deserve attention (it does), but that when it comes to formalization, it does not go far enough.

A clearer formalization of what makes sustainable chemistry different was published in January 2021 by the German ISC3 in a “dialogue paper” describing the “Key Characteristics of Sustainable Chemistry” (Table 4 based on Kümmerer et al. 2021).

Table 4 ISC3’s key characteristics of sustainable chemistry
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Table 4 is the most comprehensive and self-explanatory overview of how sustainable chemistry practitioners see the core elements of their tradition, and the lines along which it is supposed to evolve in the future. There are of course some interesting observations in the way the authors shape these key characteristics. They notably understand green chemistry in a rather narrow way, as the 12 principles, somewhat neglecting the fact these principles can be interpreted in an extremely generous manner. The frontiers of these various concepts vary depending on whom you ask. At the same time, many of these characteristics are truly unique to the sustainable chemistry project, such as for example “collaboration and transparency” to avoid greenwashing, the “holistic” character of the overall ambition, or the “sound chemicals management” which implies close interdisciplinary collaborations. In general, of all existing conceptualizations, ISC3’s is the most capable of rivaling the 12 principles of green chemistry and spreading the idea of sustainable chemistry as something genuinely different and more embracing. Whether it stands the test of time and achieves similar notoriety remains to be seen, but it appears that sustainable chemistry is currently at the same stage of development as green chemistry was in 1998.

Conclusions

In this article I have demonstrated that unlike the EPA’s green chemistry, which had some clear founding moments, sustainable chemistry grew organically. It had its roots in the 1990s, took shape in the 2000s and early 2010s, and eventually gained its own programmatic articles, as well as institutions in the second half of the 2010s and in the early 2020s. With an already developed ecosystem of journals, institutions such as the ISC3, prominent spokesmen (such as Klaus Kümmerer), and most importantly by grounding itself in the broad field of sustainability that has been promoted and endorsed by cohorts of international organizations, sustainable chemistry may appear to be a strong contender to become the term of reference for chemists in the 2020s and 2030s.

And yet, one question lingers behind this success story: after all, wasn’t sustainable chemistry created by chance? Green chemistry is not just any environmentally friendly chemistry, but the chemistry developed in the American EPA in the 1990s with its own set of institutions, rules, and manuals. Subsequent generations of chemists learning green chemistry all over the world are being educated into its frameworks. Due to a surprising historical quirk, however, this is not what happened in the German-speaking world, at least not entirely. As we have witnessed, the German industry disliked the name “green” for purely political reasons, and inadvertently paved the way for the development of an alternative vocabulary. This alternative vocabulary matured, shielded from foreign incursions, and then transformed into a full-fledged theoretical framework that assimilated green chemistry while offering a wider view of the relationships between chemistry, the environment, and society.

This evolution was far from unavoidable. For instance, even though France had an autonomous understanding of green chemistry in the 1990s, viewing it as the chemistry of bio-sourced feedstocks, the American terminology supplanted it throughout the 2000s and 2010s. Today, “chimie verte” broadly refers to the American framework, even if things are slightly more complicated, and conceptual struggles continue (Garnier 2012). What matters is that no full-fledged alternative sustainable chemistry framework was ever developed within the French institutions.

Of course, I do not claim that Germany had a monopoly over the concept. I showed that journals such as (European) ChemSusChem and (American) ACS Sustainable Chemistry and Engineering were eager to go beyond narrowly construed green chemistry. Similarly, scholars from many different countries, as illustrated by the case of the First International Conference on Sustainable Chemistry organized in Antwerp as well as a number of French articles, were interested in exploring the frontiers of sustainable chemistry. However, there is no doubt that the epicenter of the movement in favor of the latter is located in Germany where it was largely formalized.

Moreover, it would be much too far-fetched to claim that if the German scientists had fully embraced the American green terminology, their research would have contributed less to the problems of sustainability. As I have emphasized many times, proponents of green chemistry were not unaware of broader challenges, and it is likely that German scholars would have independently tackled many of these problems. However, the creation of a distinct framework for separate sustainable chemistry would not have happened and, as a consequence, at least some holistic ways of thinking that brought together chemistry and social responsibility might not have emerged.

One could say that in the grand scheme of things this does not matter, and that scholars, even without the terminology of sustainable chemistry, would have found other ways to express these ideas by, for example, modifying and expanding the understanding of green chemistry (which is also already under way), but the question is whether any theoretical framing of environmental thinking matters at all. Would chemists not have worked on designing their syntheses in a way that produced less pollution, if it hadn’t been for the 12 principles of green chemistry? Of course not, many worked on exactly this problem long before this formalization (Murphy 2018). And yet, these concepts remain helpful. On the one hand, they provide an overview of the major lines of questioning that scientists pursued in the past enhancing transparency for non-professionals and newcomers. On the other hand, they indicate important issues that need attention and outline future research agendas. They translate the language of sustainability into the realm of chemistry. In this sense, the more fleshed out concepts we have, the better prepared we are for generating new relevant research problems.

Even if green chemists are also interested in the problems of circularity and sound chemical management beyond their professional focus on environmentally benign chemical synthesis, bringing all these ideas under one roof is in itself an added value and deserves recognition. Sustainable chemistry opens new horizons not because its individual points are novel, but because thinking about them together is novel. The concept might not have gained traction if it was not for the German reluctance to embrace the English-speaking terminology. The point being made is not that the German industry was right to scold the Green party, nor does it imply that similar ideas would not have been formulated by individual researchers elsewhere: the point is that the value of the plurality of languages and independent national research traditions should not be underestimated or dismissed in science. While English became the lingua franca of empirical sciences all over the world, linguistic and cultural diversity can greatly benefit abstract theoretical frameworks and discussions on values in science and science policy.

The story of the emergence of sustainable chemistry leads to many more questions regarding the identity of scientific terminology through time and space. The term sustainable chemistry was used by the OECD and the IUPAC in the late 1990s and early 2000s as a synonym for green chemistry, and it is still understood that way in many high-profile publications. Today, however, at least among some chemists, it has acquired a much more specific meaning. How does one operate with such competing vocabularies? How do we ensure mutual intelligibility between scientists? And what about policymakers? It appears that historians of science and STS scholars are poised to play an essential role in these debates by contextualizing and historicizing the relevant terminology, as well as translating the concepts between different communities. In this sense, the humanities and social sciences make an essential part of sustainable chemistry’s interdisciplinary toolbox, as they provide the field with self-reflexivity necessary for tracing the paradigm’s past and future frontiers.