Green Chemistry 25th Anniversary Collection: From waste to resource: advancements in sustainable lignin modification

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together a very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Critical review focusing on lignin, a biopolymer found in plants and trees (DOI: 10.1039/D4GC00745J). Chemical modifications of lignin are discussed and compared to each other in terms of sustainability aspects such as waste production and safety of the employed procedures. This literature review aims to increase awareness of the environmental implications that certain chemical procedures have, moreover wants to serve as a guide for researchers and industries towards more environmentally friendly practices.

 

 

Read our interview with the authors.

How would you set this article in a wider context?

There is the need to increase awareness regarding sustainability aspects and we, as scientists, are in a key position to drive sustainable innovations and environmental awareness further. Our article addresses not only the important renewability aspect of lignin, but also emphasizes practical insights as well as safer and less waste producing approaches. Beyond academia, the concepts and methods we discuss are relevant to industries looking for ways to reduce their environmental footprint, for example by utilizing lignin byproduct as a precious starting material for further applications.

What is the motivation behind this work?

The utilization of renewable resources has been a core principle of sustainable chemistry, since Anastas and Warner introduced the 12 Principles of Green Chemistry in 1998, which lay the foundation of sustainable development in chemistry. In this context, lignin remains an underutilized and often overlooked resource. Moreover, usually protocols focus only on the renewability aspect apported by lignin, often neglecting critical factors like toxicity, waste generation, and the reliance on additional petrochemical-based reactants. Our work aims to provide a systematic overview of the key protocols present in the literature based on the environmental factor (E-factor) for waste generation as well as toxicity aspects. We also categorized protocols based on the functional groups introduced to lignin, facilitating readers seeking targeted modifications.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

The most exciting aspect of this work is the opportunity to explore and expand the potential of lignin as a sustainable resource. We are particularly enthusiastic about continuing our research into innovative and more sustainable modification techniques for this biopolymer, which could open new possibilities for its application. However, one of the main challenges we faced was obtaining sufficient data for accurate E-factor calculations, as some previous studies did not report critical information such as reaction yields for lignin modifications. We thus also hope our work encourages researchers to consistently report comprehensive data and to also apply metrics for sustainability comparison.

What is the next step? What work is planned?

This review summarizes established procedures for lignin functionalization, along with essential principles for assessing the sustainability and safety of these processes. This assessment was important for us in identifying critical issues related to lignin modification and in designing safer and more sustainable modifications protocols. We would further be very happy if our review would be of value to other research teams in helping them to develop more sustainable uses of lignin within their respective fields of expertise. Currently, we are exploring alternative methods for lignin modification focusing of the use of lignin as macromonomer for various cross-linked polymeric materials.

Please describe your journey to becoming part of the Green Chemistry community

Our group has a strong research focus on Green Chemistry for about 20 years, in particular on the utilization of renewable materials in the most sustainable way possible. It was clear from the beginning that Green Chemistry is the way to contribute to some of the most important challenges of our society. Within the last years, seeing climate change advance and the dependence on fossil resources remain high, our dedication further strengthened – we are happy to be part of this growing community and that Green Chemistry has developed to a mainstream topic over the years. With this growth and all its positive aspects of new and exciting ideas and developments, however, we have to be careful of greenwashing also in academic research.

Why did you choose to publish in Green Chemistry?

We chose to publish in Green Chemistry because it is a highly renowned journal in the chemistry field, that aligns closely with our dedication to sustainable chemistry. Our manuscript discusses and compares different protocols for lignin modification based on their adherence to the principles of Green Chemistry, making this journal the ideal platform to reach a readership dedicated to similar goals. We are excited to contribute to this field and believe our work complements the journal’s mission to promote scientific advancements in sustainable chemistry.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

The journal Green Chemistry has always set high standards in this field by publishing innovative research with sustainable chemistry practices, it was and is a highly important part for the development of the research community. As the demand for greener solutions increases, it will be essential for the Green Chemistry community to continue developing innovative methodologies, ensuring that new processes are implemented by industry in order to contribute to a sustainable development. This is not an easy task, as fossil resources and environmentally unbenign approaches are often established and economically favorable, for instance because the cost of environmental burdens or greenhouse gas emissions are externalized to society. CO2 pricing might be the necessary gamechanger here, hopefully allowing many of the advances reported by the Green Chemistry community to be put into practice. A further and ongoing requirement will be societal awareness, improved for instance by education and outreach activities.

Meet the authors

Celeste Libretti received her B.Sc. degree in Chemistry and Technologies for the Environment and Materials, and subsequently her M.Sc. degree in Industrial Chemistry, both from University of Bologna. She is currently a Ph.D. student in the working group of Prof. Dr Michael A. R. Meier, at the Karlsruhe Institute of Technology (KIT). Her research interests include cellulose and lignin structural modifications, as well as green chemistry.
Luis Santos Correa is a Ph.D. student working in the group of Prof. Dr Michael A. R. Meier at the Karlsruhe Institute of Technology (KIT). He received his B.Sc. and M.Sc. degree in chemistry from KIT. His master thesis focused on the oxidative cleavage of sunflower oil. He is currently working on the synthesis of polycarboxylic acids from renewable resources and their potential application in polymer chemistry.
Michael A. R. Meier studied chemistry in Regensburg (Germany) and received his Ph.D. from the Eindhoven University of Technology (The Netherlands) in 2006. After further stays in Emden and Potsdam, he was appointed as full professor at the Karlsruhe institute of Technology (KIT) in 2010. He has received several awards and is associate editor of ACS Sustainable Chemistry & Engineering. His research interests include the sustainable use and derivatization of renewable resources for polymer chemistry as well as the design of novel highly defined macromolecular architectures.
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Green Chemistry 25th Anniversary Collection: Green liquid marble-based hydrogels as pesticidal pyrethrin slow-release carriers

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together a very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Paper on a strategy to prepare hydrogel drug slow-release carriers for efficient mosquito larvae extermination using green biodegradable materials. (DOI: 10.1039/D3GC03625A).

This strategy provides a new way to expand the application of liquid marbles in green chemistry. The highly stable, highly loaded, and biodegradable slow-release hydrogel carrier was prepared based on liquid marble utilizing green and cheap materials for loading pyrethrin to kill mosquito larvae. The liquid marble endowed the drug carrier with superior floating stability at the water surface to kill mosquito larvae hanging below the water surface for survival and the electrostatic interaction between alginate and gelatin of this carrier can effectively reduce the degradation rate of pyrethrin in water exhibiting a long drug release time.

 

Read our interview with the authors.

What is the motivation behind this work?

People living in humid environments, especially next to lakes and swamps and in rainforests, are often attacked by mosquitoes. So we wanted to prepare a green biodegradable drug slow-release carrier loaded with green anti-mosquito drug (pyrethrin) to kill mosquitoes without damaging the local environment.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

We find it most challenging to use the green route to impart good hydrophobicity and superior material stability to the drug carriers, and we are very excited about the long drug release time and superior floatation and storage stability of the drug carriers we have prepared.

What is the next step? What work is planned?

Our next steps will be to explore some research around liquid marbles in other directions of green chemistry. We will use the characteristics of liquid marbles to do some work in the fields of drug loading, adsorption and separation, and catalysis.

Please describe your journey to becoming part of the Green Chemistry community?

We wanted to reduce the number of mosquitoes in our living environment through green chemistry without damaging the environment, so we did work in this area. Green Chemistry, a top journal in the field of chemistry focusing on green chemistry and sustainability, was a perfect fit for our work, so we published our work in Green Chemistry.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

We consider that what the Green Chemistry journal has done best over the past 25 years is to provide a unique forum for the publication of innovative research in green chemistry as well as sustainable development. green chemistry is at the forefront of an evolving interdisciplinary field, so it is important to keep an eye out for innovative advances in green chemistry across disciplines.

Meet the authors   

Qihui Zhang is a Professor of Pharmaceutical Chemistry at Chongqing University, who received his PhD degree from Shenyang Pharmaceutical University. As a senior visiting scholar, he finished his advanced study at the University of Chicago under the tutelage of Chair Professor Chun-Su Yuan. Professor Zhang is also the invited reviewer for more than ten top international journals. The main research interests of Professor Zhang include extraction, separation and structural modification of natural products based on molecular imprinting technology and nanotechnology.
Liandi Zhou, born in 1978, Ph.D., graduated from China Medical University in 2008, Associate Professor, Director of Pathogenic Biology and Immunology Department, School of Basic Medical Sciences, Chongqing College of Traditional Chinese Medicine, Director of Chongqing Microbiology Society, and former expert of Chongqing Municipal Science and Technology Commission for reviewing medical projects. He has participated in one national-level project, two school-level projects of Chongqing Medical University, two planning textbooks of Science Press, and one school-level teaching reform project of Chongqing Medical University, and has published five papers on teaching reform. Her main research interests include the regulation of immune-related diseases by active ingredients of traditional Chinese medicine and their mechanisms, and she has published more than 20 SCI papers as a corresponding author.
Dr. Saimeng Jin obtained his PhD degree in chemistry from the University of York (United Kingdom, with Prof. James Clark) in 2017 and his BSc degree from the Sichuan University (China, with Prof. Bi Shi) in 2010. He currently works as a Associate Professor at the School of Chemistry and Chemical Engineering, Chongqing University. He hosts the National Natural Science Foundation of China (No. 22208036). His research interests include dimethyl carbonate chemistry, conversion of biomass.
James Clark is Professor of Chemistry at the University of York, and is Founding Director of the Green Chemistry Centre of Excellence and the Bio-renewables Development Centre. He is also Chair Professor at Fudan University in China and holds honorary doctorates at the Universities of Ghent, Leuphana and Umea. He is a Visiting Professor at Sichuan University and was the International Visitor at the University of cape Town. He has won prizes and awards from many organisations including the 2018 Royal Society of Chemistry Green Chemistry Prize and the 2021 European Sustainable Chemistry award. His research involves the application of green chemical technologies to waste or low value feedstocks notably biomass so as to create new green and sustainable supply chains for chemical and material products. Some of his discoveries in research include a new bio-based solvent Cyrene® to replace toxic amides (produced by Circa Group Ltd including in a new €50M manufacturing plant in France), unique bio-based carbonaceous materials (commercialised through his award-winning spin-out company Starbons® Ltd with applications in areas including medical devices) and new routes to waste plastics recycling (through his new spin-out company Addible.Ltd). James has also been very actively involved in green chemistry publishing, education and networking: he was founding editor of the world-leading Green Chemistry journal, heads the advisory board for the RSC Green Chemistry book series and he was founding director of the worlds’ longest running green chemistry MSc program as well as the Green Chemistry network and the Global Green Chemistry Centres network. (“G2C2”).

 

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Green Chemistry 25th Anniversary Collection: Solvent effects on carbohydrate transformation: insights into chemical pathway modulation

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together a very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Critical Review that summarizes the primary types of carbohydrate chemical transformation and commonly used solvent systems, providing an overview of solvent effects in these reactions and an insight into solvent effects from a microscopic perspective (DOI: 10.1039/D3GC04901A)

The review also provides relevant insights into the current status and challenges of solvent engineering, contributing to the solvent construction of carbohydrate reaction systems.

Read our interview with Haipeng Yu, the corresponding author here:

How would you set this article in a wider context?

The development of biomass resources is progressively moving towards refinement for higher-value benefits. Carbohydrates are an important component of biomass resources, and the chemicals obtained from their chemical derivatization are key intermediates in the production of biofuels, bioplastics, pharmaceuticals and fine chemicals, which makes carbohydrate resources a favourable alternative to traditional fossil energy sources. This article provides relevant insights into how solvent effects modulate carbohydrate reactions and also offers key information to optimize the reactions and improve their sustainability and environmental friendliness. The modulation of chemical pathways by solvents is a pervasive application. This article not only advances the understanding of biomass-derived chemical production, but also contributes to broader fields such as organic synthesis, materials science, industrial process design and green chemistry. It is hoped that this article will resonate across disciplines and provide a reference for more sustainable, efficient and targeted chemical processes.

What is the motivation behind this work?

We hope that this work will inspire future rationalized solvent design for specific chemical reactions. By understanding the mechanisms by which solvents regulate carbohydrate conversion pathways, researchers can develop novel and practical solvent systems that will improve the reaction efficiency and sustainability of a range of chemical processes.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

The most interesting and challenging part of this work is the exploration and demonstration of the interaction between the solvent and other substances in the reaction system. The influence of solvent regulation on experimental results can be jointly supported through experimental control and microscopic simulation.

What is the next step? What work is planned?

In the next step, we plan to utilize solvent effects to develop related fine chemicals based on the sugar platform.

Please describe your journey to becoming part of the Green Chemistry community.

My journey began in my graduate studies when I recognized the environmental impact of traditional chemical processes, and I was inspired by sustainable chemistry to delve deeper into biomass conversion. I have been working on projects with my teachers and fellow students on green catalysts, synthetic routes, and bio-based materials. In the process I have come to understand the Green Chemistry community and become a part of it. In the future, I will take green chemistry as my purpose and continue to focus on the development of sustainable biomass conversion and utilization.

Why did you choose to publish in Green Chemistry?

I chose to publish in Green Chemistry because it aligns with the commitment to advancing sustainable and environmentally friendly chemical processes. The journal is a leading platform for cutting-edge research that promotes the principles of green chemistry. By publishing in Green Chemistry, I have the opportunity to contribute to a global community of scientists who are focused on developing innovative, sustainable solutions that address environmental challenges.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

Over the past 25 years, Green Chemistry has played a pivotal role in advancing sustainable science by providing a respected platform for researchers to share groundbreaking work on environmentally friendly chemical processes. The journal has successfully promoted the 12 Principles of Green Chemistry, helping shift industry and academic focus toward designing safer chemicals, using renewable resources, and minimizing waste. It has also facilitated collaboration between chemists, engineers, and policy-makers, driving practical applications of green technologies in industries like pharmaceuticals, energy, and materials science.

However, as we look ahead to the next 25 years, scaling sustainable technologies for widespread industrial adoption remains a major hurdle, as many green alternatives still struggle to compete economically with conventional processes. The journal may need to focus more on scaling up the practicality and economics of green chemistry processes. Additionally, as global environmental policies and regulations evolve, the journal may need to adjust its focus and content to remain relevant and impactful, including a greater emphasis on topics such as chemical recycling, renewable resource, and carbon footprint reduction.

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Green Chemistry 25th Anniversary Collection: Deep eutectic solvents as green solvents for materials preparation

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together a very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Critical Review on the application of Deep Eutectic Solvents (DESs) in the materials preparation process, starting from their unique and significant properties, combined with specific examples to propose how to design solvent systems according to various demands and purposes (DOI: 10.1039/D4GC00136B). The combination of green chemistry principles with innovative material design is expected to reshape industry technologies in a sustainable, efficient, and cutting-edge manner.

Read our interview with the corresponding authors

How would you set this article in a wider context?

This article not only provides a comprehensive summary of fundamental research but is also supported by practical case studies, offering convenience for chemists and material scientists in their research. Additionally, the economic feasibility and environmental impact have been evaluated, which may serve as a reference for policymakers.

What is the motivation behind this work?

The study of the properties of DESs has become quite mature, and therefore, their effective use has become a focal point. The heterogeneity of DESs is a characteristic of these solvents, but what is its relationship with morphology control? Why can DESs function not only as solvents but also as templates and reducing agents? These deeper questions have been explored, but systematic discussions and comparisons are lacking. We have bridged two aspects of this field: starting from the excellent solubility of DESs to the preparation of various functional materials.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

Pairwise summarization of work presents challenges, for example, inserting-leaching, etching-coating, doping-compositing, bottom-up and top-down approaches. Additionally, summarizing the electrodeposition of pure metals and common alloys is also a complex task.

What is the next step? What work is planned?

Moving forward, our work will continue to focus on green chemistry research in the following areas:
a. Forestry Resource Chemistry: pretreatment and high-value conversion of biomass and platform compounds
b. Resource and Environmental Chemistry: separation and purification of greenhouse gases, VOCs, waste plastics, minerals, and electronic waste

Why did you choose to publish in Green Chemistry?

All along, Green Chemistry is one of the most influential journals in this field. Green synthesis, green manufacturing and green energy are all inseparable from the basic concept of green chemistry. We believe that this work will demonstrate its greatest impact here.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

From the proposal of the 12 principles of green chemistry to the establishment of the journal Green Chemistry, scientists have gradually built a solid foundation for their research efforts. We believe that over the past 25 years, Green Chemistry as a publication has consistently promoted the concept of a sustainable society and the continuous development of humanity. In the next 25 years, the key will be how to attract high-quality research for publication, especially given the intense competition already evident within the publishing industry. More importantly, it is crucial to gain insights into the chemical elements involved in green development, thereby guiding progress in related fields.

Meet the corresponding authors

Prof. Tiancheng Mu received his Ph.D. in physical chemistry from the Institute of Chemistry, the Chinese Academy of Sciences, in 2004. He worked in the Department of Industrial Chemistry, Oldenburg University, as a postdoc from 2005 to 2007. He is currently a full professor in the Department of Chemistry, Renmin University of China. He has authored over 200 peer-reviewed scientific publications and six book chapters. He currently serves as an Associate Editor for RSC Advances, and as an Advisory Board Member for CLEAN – Soil, Air, Water. He is vice-director of the Ionic Liquids Committee of the Chemical Industry and Engineering Society of China.
Prof. Zhimin Xue received her Ph.D. degree from Renmin University of China in 2014. From 2018 to 2019, she was a visiting associate professor at the University of Tennessee, Knoxville. She is currently a professor at Beijing Forestry University. Her research interests cover the treatment and conversion of biomass, design, and applications of green solvents. Furthermore, she was awarded the Prize of Liangxi Forestry Science and Technology Award and the Science and Technology Award of the China Association for Instrumental Analysis. She was selected for the National High-level Talent Special Support Plan in 2021.

 

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Green Chemistry 25th Anniversary Collection: The need to integrate mass- and energy-based metrics with life cycle impacts for sustainable chemicals manufacture

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together a very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Paper on quantifying  the level of correlation and linkages between five mass- and energy-based metrics and 16 LCA indicator scores by leveraging data for over 700 chemical manufacturing processes (DOI: 10.1039/D4GC00394B)

Synthetic chemicals are essential to everyday life, supporting everything from food security and health care to electronics and clothing. Scientists and engineers are constantly searching for greener production routes, but designing them requires methods to quantify their environmental impact. This article evaluates different metrics of varying complexity, identifying their pros and cons.

Read our interview with Javier Pérez-Ramírez and Gonzalo Guillén-Gosálbez

How would you set this article in a wider context?

Global chemical demand is projected to grow by 40% this decade, while the chemical industry faces mounting pressure to reduce its substantial environmental footprint. We highlight the critical role of metrics in assessing environmental impacts and emphasise the importance of a holistic approach to guide prioritisation and more informed decision-making.

What is the motivation behind this work?

Overall, our goal is to promote the broad adoption of quantitative metrics in research. The global aspiration of the community to make the world a better place through chemistry often relies on narrow or simplified indicators, leading to unclear environmental benefits. We addressed this by using more comprehensive and standardised approaches across a wide range of key chemical processes to understand the differences in the information they provide.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

We’re particularly excited about how comprehensive sustainability metrics like life cycle assessments (LCA) can rank chemical processes based on diverse environmental impacts, going beyond the CO2 footprint. Our results indicate that different methods present distinct advantages and trade-offs across various environmental criteria. Current challenges include the limited availability and uncertainty of openly accessible data, as well as the need to bring the experimental and systems engineering communities closer in the coming years.

What is the next step? What work is planned?

We conclude from our results that increasing the use of comprehensive LCA in early research stages is key. To address this, we aim to make these environmental analyses more accessible through user-friendly tools. Additionally, we will focus on data standardisation and robust methods for managing data uncertainty, as well as proposing effective schemes for ranking chemicals based on distinct impacts, which remains challenging.

Please describe your journey to becoming part of the Green Chemistry community

We view our journey into the Green Chemistry community as a natural progression of our commitment to making a positive societal impact. Chemistry will play a pivotal role in implementing the sustainable development goals and combating climate change, and we believe that embracing the guiding principles of Green Chemistry is essential for this mission within an interdisciplinary approach.

Why did you choose to publish in Green Chemistry?

We chose Green Chemistry for its unique focus on alternative green technologies and sustained leadership in the field. The themed collection ‘Measuring Green Chemistry: Methods, Models, and Metrics‘ aligns with our focus on quantifying environmental impacts, making it the ideal platform for our study.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

Green Chemistry has been instrumental in uniting a diverse community under a shared philosophy grounded in the Green Chemistry principles and has successfully adapted to the evolving landscape of sustainable chemistry. As mentioned above, one of the major challenges will be achieving the application of standardised metrics in both academic and industrial arenas, for which different stakeholders must collaborate.

 

 

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Green Chemistry 25th Anniversary Collection: A robust heterogeneous chiral phosphoric acid enables multi decagram scale production of optically active N,S-ketals

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together as very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Paper on the application of a highly recyclable heterogeneous catalyst to the multi-decagram synthesis of enantiomerically enriched molecules in continuous-flow using a 2 mL reactor. The combination of this catalyst with a new reactor design increased the productivity from milligrams to up to 20 g scale in a few hours while reducing the overall environmental impact of the reaction (DOI: 10.1039/D4GC00019F)

Organocatalysis has become one of the pillars of asymmetric catalysis along with metal and enzyme-catalyzed reactions. Its potential was recognized in 2019 by the IUPAC, as a part of the top 10 emerging technologies in chemistry, and by the Nobel Prize awarded to Benjamin List and David MacMillan in 2021.However, these reactions are often too inefficient due to the high catalyst cost and scalability issues, leading to limited applicability in the industry. In this context, developing heterogeneous catalysts can simplify the recycling process, making catalytic processes more efficient and contributing to minimizing the overall cost and environmental impact of the reaction.

Read our interview with Aitor Maestro and C. Oliver Kappe

What is the motivation behind this work?

Although the use of heterogeneous catalysts and continuous flow technology in asymmetric catalysis is not new, the productivity of known processes is often rather limited. Developing new and reliable enantioselective processes for reproducing batch reactions on a large scale requires a combination of chemical and technical solutions. In this article, we wanted to illustrate the potential of combining these techniques to achieve higher productivity and set up a precedent for future developments in the field.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

One of the most exciting results of this project was the high robustness of the heterogeneous catalyst. While similar homogeneous reactions often require 2-10 mol% of the catalyst, we managed to decrease it up to 0.1%. Moreover, the analysis of the catalyst after the reaction did not show any visible physical or chemical degradation, indicating it could be used for much longer.

One of the biggest challenges is the development of new heterogeneous catalysts that efficiently mimic the behaviour of their homogeneous counterparts. While solid supports facilitate the recycling process, they can also affect the reactivity.

What is the next step? What work is planned?

We are willing to further explore the potential of highly active heterogeneous chiral catalysts for other applications in the future. We want to apply them to the synthesis of key chiral building blocks and active pharmaceutical ingredients.

Please describe your journey to becoming part of the Green Chemistry community

Integrating technical solutions with intricate catalytic reactions helps reduce the overall waste, create more sustainable chemical processes, and enhance reaction efficiency. Therefore, focusing on the intersection of catalysis and technology aligns perfectly with the principles of green chemistry.

Why did you choose to publish in Green Chemistry?

This is one of the leading journals in the field of green chemistry research. We thought our work involving catalyst recyclability studies and waste reduction of the reported enantioselective reaction was a good fit for the scope of the journal.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

One of the biggest challenges for the journal is being focused on a constantly changing field. Many aspects of green chemistry are often directed by global trends or new legal regulations. Some current challenges that will probably get more attention in the coming years are obtaining raw chemicals from renewable sources such as CO2 or the development of economically viable catalytic processes.

Meet the corresponding authors

Aitor Maestro obtained his PhD (2019) from the University of the Basque Country, working on asymmetric organocatalysis. After two postdoctoral stays (University of Groningen, and University of St. Andrews), in 2022, he obtained a Postdoctoral Fellowship from the Basque Government, allowing him to spend two years at the University of Graz working on asymmetric catalysis in continuous flow before moving back to the University of the Basque Country, where he is currently working on independent projects related to the development and applications of recyclable chiral catalysts.
Oliver Kappe received his diploma (1989) and his doctoral (1992) degrees in organic chemistry from the University of Graz and after two postdoctoral stays (University of Queensland and Emory University) returned to Graz in 1996 to start his indepenent acacdemic career and was appointed Full Professor in 2011. For the past decade the focus of his research has been directed towards flow chemistry/microreaction technology, encompassing a wide variety of synthetic transformations and experimental techniques.

 

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Green Chemistry 25th Anniversary Collection: A comparative study of palladium-gold and palladium-tin catalysts in the direct synthesis of H2O2

Over the past 25 years, Green Chemistry has provided a unique forum for the publication of innovative research on the development of alternative sustainable technologies, efficient utilisation of resources and the concomitant minimisation of waste. We are delighted to bring together a very special issue containing articles by members of the green chemistry community as well as past and present Green Chemistry Board members, to mark and celebrate our first 25 years.

Among the contributions to this themed collection is a Paper on the promotive effect of Au and Sn incorporation into supported Pd nanoparticles for the direct synthesis of H2O2 from molecular H2 and O2  (DOI: 10.1039/D3GC03706A).

The direct synthesis of H2O2 from the elements represents an atom-efficient alternative to the current indirect industrial process, allowing for localised production of a major commodity chemical used in sectors as varied as chemical synthesis, bleaching and disinfection. However, despite over 100 years of research, few examples of highly selective catalysts (i.e. those that do not degrade H2O2 to H2O), exist. Catalysts based on PdAu and PdSn active sites are an exception to this generality and this work compares and contrasts the efficacy of these two systems towards H2O2 production and demonstrates the excellent performance metrics which can be offered by these two distinct classes of materials.

Read our interview with Dr Richard J. Lewis, one of the authors, here.

How would you set this article in a wider context?

AuPd catalysts have been well studied in recent decades for a range of chemical transformations, including H2O2 synthesis. However, the replacement of Au with Sn, and the resulting improvement in catalytic efficiency that results, is a relatively new discovery, with earlier works in this area focussed on (i) the use of complex catalyst synthesis protocols to form Sn overlayers that encapsulate highly active yet unselective Pd species or (ii) the study of idealised, model PdSn catalysts in order to gain a fundamental understanding of the structure-reactivity relationships that exist in such systems.

Importantly the materials studied within this work are produced via a readily scalable synthesis protocol and compete with state-of-the-art materials reported within the academic literature, including those previously reported by our laboratory. Crucially they can achieve the high selectivity necessary for the direct route to H2O2 synthesis to compete with the current industrial approach to production.


What is the motivation behind this work?

Despite calls for uniformity in testing regimes, it is typical for stark differences in catalyst evaluation protocols and reaction conditions to exist between research groups. This is somewhat understandable given that researchers wish to evaluate catalytic performance under conditions idealised for their particular system, as well as allowing  for benchmarking against earlier works from their own laboratory. However, this often leads to confusion as to the current state-of-the-art, with comparison of catalysts, especially those from different laboratories, under standardised conditions rarely performed. In this work, we set out to address this concern, comparing and contrasting the performance of a series of catalysts based on the well-established AuPd formulation, against the emerging class materials centred around PdSn.

What aspects of this work are you most excited about at the moment and what do you find most challenging about it?

The performance of our 0.25%Pd–2.25%Sn/TiO2 catalyst is particularly exciting, offering near-total selectivity towards H2O2 and product yields superior to the optimised AuPd formulation. Indeed, the performance of this catalyst can be considered among the state-of-the-art.  The mechanism by which this improved reactivity is achieved is also intriguing, with the addition of high quantities of Sn promoting Pd dispersion and the formation of highly active and selective, single atoms of Pd surrounded by Sn/SnOx domains, rather than through the formation of PdSn alloys as may have been expected based on earlier works.

What is the next step? What work is planned?

While these systems are highly promising it is important to note that they represent only the first generation of materials developed in this project. As such our focus has now shifted towards the redesign and further optimisation of these catalyst formulations to ensure the key performance metrics (high reactivity and near-total selectivity towards H2O2) are maintained over industrially relevant lifetimes. We are also actively pursuing the translation of these research-grade catalysts into technical-grade materials to allow for further evaluation under realistic operating conditions, as well as use in alternative chemical transformations centred around the utilisation of in-situ synthesised H2O2.  We are also seeking a greater understanding of the dynamic nature of these systems during catalysis, through the use of operando and in-situ characterisation techniques. This is particularly exciting and allows us the opportunity to collaborate with colleagues from fields adjacent to catalysis, including spectroscopists and microscopists.

Please describe your journey to becoming part of the Green Chemistry community

Engineering a more sustainable world aligns perfectly with the aims of the Green Chemistry and Catalysis communities, as such it is easy to consider the members of these two fields as part of the same family, rather than belonging to two distinct communities whose goals are sometimes shared.  Therefore there has not been a journey towards a Green Chemistry community, rather there is a shared journey with friends and colleagues of one community.

Why did you choose to publish in Green Chemistry?

Green Chemistry is, without doubt, one of the flagship journals in the field of sustainability, built on the foundations laid out by Paul Anastas and Nicolas Eghbali and nurtured by past and present members of the journal Editorial Board. One of the major themes of  Green Chemistry is to find solutions to many of the grand challenges facing the chemical industries through the design, synthesis and evaluation of novel materials and alternative processes. We consider that our manuscript aligned very well with these ambitions and given the broad readership of the journal, we could think of no better home than Green Chemistry.

What do you think the Green Chemistry journal has done well in the past 25 years, and what do you think are the main challenges our community will face in the next 25 years?

For the past 25 years, Green Chemistry has been at the forefront of advances in sustainability and environmental protection, continually promoting the development of new technologies that improve efficiency and minimise the impact of the chemical sector, both to humans and the wider ecosystem. A major challenge facing the chemical sector has and will continue to be the transition towards manufacturing processes that better utilise raw materials and minimise the production of waste by-products. This challenge will only grow with the transition toward alternative, non-fossil-derived feedstocks supplied from a wide variety of sources.  The drive towards Net Zero poses both challenges and opportunities for the field, with the emergence of new feedstocks including sequestered CO2, NH3,  biomass and carbon-free H2 requiring the development of new processes and modifications to existing technology. The associated shift towards electrification will also result in changes in supply/demand dynamics of critical elements that will undoubtedly result in increased utilisation of many earth-abundant metals (e.g. for use in energy storage), while the shift away from fossil fuel-based transit will have unpredictable effects on the supply of many of the precious metals that are utilised in petroleum refining and automotive exhaust treatment and have been the backbone of the chemical synthesis sector.

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Green and Sustainable Chemistry Symposium – a celebration of 25 years of the journal Green Chemistry

On June 24th 2024, the Green and Sustainable Chemistry Symposium – a celebration of 25 years of the journal Green Chemistry, co-sponsored by the Royal Society of Chemistry, Asynt and the University of York Department of Chemistry, was held.  This conference not only marked the 25th anniversary of the journal Green Chemistry but was a fantastic first major event for York’s Green and Sustainable Chemistry Research Theme.
It covered a deliberately broad programme, with contributions from both academia and industry, and topics ranging from valorisation of biomass, and teaching of green chemistry, to electrochemistry, reactor design and Bismuth chemistry – maybe not something people might first expect at this sort of symposium, but when compared with previous mercury chemistry the sustainability advantages were clear.
Prof Helen Sneddon hosted the event, and there were 11 excellent talks, challenging the audience to think about Green chemistry beyond usual preconceptions.  There was active discussion between speakers and attendees – who included both University of York researchers taking advantage of the event on home turf, and academic and industry researchers who had travelled from around the UK.

The poster session, which contained posters from Postdoctoral Research Assistants, PhD students, and 1 Masters student (indeed one of the 2 poster prize winners) prompted further discussion. Also notable was one poster with a detailed analysis of a Chemistry Department’s road to net zero prompting discussions about the sustainability of laboratory research – a topic of much recent interest.

The supplier, and co-sponsor Asynt showcased a range of laboratory equipment, including an electrochemical reactor designed by, and featuring in, one of the talks by Charlotte Willans.

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International Symposium on Green Chemistry – ISGC 2025

Green Chemistry is delighted to support the International Symposium on Green Chemistry – ISGC 2025 which will be held in La Rochelle, France from May 12-16, 2025. There will be plenary conference and keynotes, 320 oral communications, start up pitch sessions and poster sessions.

About this conference

The conference aims to gather the most eminent scientists involved in the field of green chemistry to debate on the future challenges of chemistry, keeping in mind the problems of access to a sustainable energy, the management of resources (carbon, water, metals, minerals), human development, global warming, impact on the environment and competitiveness of industry.

Among the speakers are Green Chemistry’s Editorial Board Member Serenella Salla (European Commission – Joint Research Centre, Italy), and Green Chemistry’s Advisory Board Member Douglas MacFarlane (Monash University, Australia). A complete list of the Plenary lectures and Keynotes can be found here

Call for abstracts

  • The call for abstracts (oral communication) will be open from September 30, 2024 to December 15, 2024.
  • The poster submission deadline is April 15, 2025

Create your account and submit your abstract online here.

Themed collection

As art of our partnership, Green Chemistry and RSC Sustainability will be publishing a selection of papers based on presentations at this event in a Themed Collection Guest Edited by François Jérôme (University of Poitiers, France).

The collection comprising articles based on presentations from the International Symposium on Green Chemistry 2022 meeting held in La Rochelle, France between 16th-20th May 2022 can be found here

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Green Foundation box

The Green Foundation box

From the beginning of December 2024, all submitted manuscripts to Green Chemistry must include a Green Foundation box. This box should contain three numbered points answering three specific questions based on the article type (140 words maximum). This box will be seen by the editor and reviewers and will help them ascertain the green advance that the work presents. If the manuscript is accepted this box will also be published. Manuscripts cannot be considered by the editor or reviewed without this box. More information can be found in this Editorial

The questions to be answered are:

Primary research: Communications and Full Papers
1. How does your work advance the field of green chemistry?
2. Please can you describe your specific green chemistry achievement, either quantitatively or qualitatively?
3. How could your work be made greener and be elevated by further research?

 Secondary research: Critical reviews, Tutorial reviews, and Perspectives
1. What advances in green chemistry have been discussed?
2. What makes the area of study of significant wider interest?
3. What will the future of this field hold, and how will the insight in your review help shape green chemistry science?

Examples

The Editorial Office, in collaboration with past and present Editorial Board Members, have put together a list examples based on recently published articles.

Click below to read the examples.

Article type: Communications
.
Electrochemical-induced benzyl C–H amination towards the synthesis of isoindolinones via aroyloxy radical-mediated C–H activation
M. Yu, Y. Gao, L. Zhang, Y. Zhang, Y. Zhang, H. Yi, Z. Huang and A. Lei
Green Chem., 2022, 24, 1445-1450. DOI: 10.1039/D1GC04676D

Green foundation
  1. We report a cost-effective, safe, and sustainable electrochemical strategy to effectively and selectively realize benzyl C–H amination via aroyloxy radical-mediated C–H activation. With this strategy, we are able to rapidly synthesize a set of valuable isoindolinones by using easily available o-alkyl benzoic acids and nitriles as starting materials under mild conditions without the use of transition metal catalysts and external oxidants.
  2. The synthetic value of this method is also illustrated by post-derivatizations to newly accessible scaffolds, thus paving the way towards versatile molecules of interest with potential pharmaceutical applications. We present a “green” concept starting with simple starting materials and through sustainable reaction conditions we provide an effective synthetic pathway to a series of pharmaceutically relevant isoindolinones.
  3. It will be beneficial for organic chemists to access pharmaceuticals and natural products involving lactam skeletons, therefore, making contributions to the new drug development.

A highly active, thermally robust iron(iii)/potassium(i) heterodinuclear catalyst for bio-derived epoxide/anhydride ring-opening copolymerizations

W. T. Diment, G. Rosetto, N. Ezaz-Nikpay, R. W. F. Kerr and C. K. Williams
Green Chem., 2023, 25, 2262-2267. DOI:10.1039/D2GC04580J

Green foundation
  1. We investigate the synthesis of degradable polyesters from sustainable monomers mediated by an earth abundant metals, iron and potassium.
  2. The catalyst showed field-leading activity and selectivity for highly challenging, renewable monomers. It efficiently produced a series of amorphous, high Tg (>100 °C) polyesters, which carry significant potential as degradable thermoplastics, engineering polymers, resins and vitrimers.
  3. The Fe(iii)/K(i) combination should be tested with other ancillary ligands and as catalysts targeted for other sustainable polymerizations, e.g. carbon dioxide/epoxide ROCOP or lactide, lactone or cyclic carbonate ring-opening polymerizations which may benefit from heterodinuclear synergy.

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Article type: Full papers
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Assessing the environmental benefit of palladium-based single-atom heterogeneous catalysts for Sonogashira coupling
D. Faust Akl, D. Poier, S. C. D’Angelo, T. P. Araújo, V. Tulus, O. V. Safonova, S. Mitchell, R. Marti, G. Guillén-Gosálbez and J. Pérez-Ramírez
Green Chem., 2022, 24, 6879-6888. DOI: 10.1039/D2GC01853E

Green foundation
  1. This study quantitatively assesses through life-cycle analysis (LCA) possible environmental benefits of replacing soluble palladium organometallic complexes with single-atom heterogeneous catalysts in cross-coupling reactions, exemplified for the Sonogashira reaction.
  2. Reusing the heterogeneous catalyst once, assuming its stability and full metal retention, can already deliver advantages in various impact categories over the conventional homogeneous systems, with the potential for orders-of-magnitude improvements. The LCA results provide criteria for implementing solid, reusable catalysts in sustainable organic transformations.
  3. In future work, the presented LCA framework may inform catalyst design and help streamline research efforts toward more sustainable catalytic materials.

High performance, but low cost and environmental impact? Integrated techno-economic and life cycle assessment of polyoxazolidinone as a novel high-performance polymer
M. Bachmann, A. Marxen, R. Schomäcker and A. Bardow
Green Chem., 2022, 24, 9143-9156. DOI:10.1039/D2GC02400D

Green foundation
  1. This work assesses the economic and environmental potential of polyoxazolidinones (POX) as high-performance thermoplastics.
  2. A combined techno-economic and life-cycle assessment shows that POX reduce the carbon footprint of high-performance thermoplastics at competitive costs even for fossil-based production. Employing biomass could further reduce the carbon footprint but would introduce environmental trade-offs such increasing freshwater eutrophication.
  3. POX are identified as promising as high-performance thermoplastics, but the assumed material performance needs to be confirmed experimentally and environmental trade-offs considered in detail before large-scale implementation.

Early-stage impact assessment tool (ESTIMATe) for the life cycle assessment of CO2-based chemicals
H. Minten, B. D. Vandegehuchte, B. Jaumard, R. Meys, C. Reinert and A. Bardow
Green Chem., 2024, 26, 8728-8743. DOI:10.1039/D4GC00964A

Green foundation
  1. This work introduces a software tool allowing non-experts to perform early-stage life-cycle assessment for CO2 conversion processes.
  2. The open-source Excel tool ESTIMATe is provided that automates and streamlines life-cycle assessment of carbon capture and utilization processes. LCA assumptions are automated and estimation tools are provided to fill data gaps. Thereby, ESTIMATe makes environment assessments accessible to non-experts even at early-stages of development.
  3. Deployment of the ESTIMATe tool will hopefully improve early-stage decision making and also help to refine the tool itself. Future developments are to expand the scope beyond CO2 conversion.

Introducing the use of a recyclable solid electrolyte for waste minimization in electrosynthesis: preparation of 2-arylbenzoxazoles under flow conditions
F. Ferlin, F. Valentini, F. Campana and L. Vaccaro
Green Chem., 2024, 26, 6625-6633. DOI:10.1039/D4GC00930D

Green foundation
  1. The work introduces the use of solid electrolyte into organic electrosynthesis, and it proves that with this approach is possible to significantly reduce the waste associated to the use of stochiometric classic homogeneous electrolyte generally containing halides
  2. Calculation of the green metrics (E-factors, RME, MRP) for the newly defined procedure and several literature examples, allow to quantify the specific achievement. E-factor has been reduced of ca. 82-99%. Mass of the electrolyte generally constitutes 25–68% of the entire E-kernel and in our case, we could obtain a very low value of 0.12%.
  3. Future research will be dedicated to expanding the utilization of solid electrolyte in different electroassisted processes using with safe recoverable reaction media.

Valorisation of phenols to coumarins through one-pot palladium-catalysed double C–H functionalizations
G. Brufani, F. Valentini, F. Sabatelli, B. Di Erasmo, A. M. Afanasenko, C.-J. Li and L. Vaccaro
Green Chem., 2022, 24, 9094-9100. DOI:10.1039/D2GC03579K

Green foundation
  1. The use of a novel synthetic strategy based on the Pd/C catalysed C−H functionalization of substituted phenols has allowed the direct synthesis of prenylated coumarins. The multistep protocols for the synthesis of osthole-like derivatives, which frequently use toxic reagents and non-recyclable catalysts, could be replaced using our one-pot procedure, which has proven to be efficient in the synthesis of biologically active products.
  2. Our newly procedures for the synthesis of osthole derivates showed significant improvement in terms of atom economy, from 32% to 81%. For direct comarin synthesis, the waste was reduced up to 56% and the efficient recovery and reuse of heterogeneous catalytic system has allowed a TON value of 41 (over 5 consecutive runs) which is greater than the value obtained for analogous homogeneous systems (6.2–32.3).
  3. Further work on the kinetics and the mechanism would aid in future research particularly for other derivatives

Aerobic waste-minimized Pd-catalysed C–H alkenylation in GVL using a tube-in-tube heterogeneous flow reactor
F. Ferlin, I. Anastasiou, L. Carpisassi and L. Vaccaro.
Green Chem., 2021, 23, 6576-6582. DOI:10.1039/D1GC01870A

Green foundation
  1. We utilize an efficient flow reactor system for the Fujiwara–Moritani C–H alkenylation reaction of biomass-derived γ-valerolactone. The protocol features very limited metal leaching, high stability of the catalyst, and applicability to a range of substituted acetanilides and N-methoxybenzamides and others.
  2. By using the flow reactor system, the external oxidant could be minimised, which also reduced leaching of the palladium catalyst (from ca. 4 ppm to 0.2–0.02 ppm). The use of biomass derived GVL as the reaction medium also reduced metal leaching by almost an order of magnitude to the next best solvent. By comparing to protocols in the literature, the E-factor value of our newly defined protocol is 80->99% lower and the reaction mass efficiency and materials recovery parameter are noticeably improved.
  3. When scaling up, an efficient recovery process for the leached palladium would be critical for a sustainable system.

Non-noble metal heterogeneous catalysts for hydrogen-driven deoxydehydration of vicinal diol compounds
J. Gan, Y. Nakagawa, M. Yabushita and K. Tomishige.
Green Chem., 2024, 26, 8267-8281. DOI:10.1039/D4GC02006E

Green foundation
  1. From the viewpoint of carbon neutrality and carbon recycling, the synthesis of biomass to valuable chemicals using greener catalysts is increasingly important. The present work shows the development of non-noble metal catalysts for deoxydehydration (DODH).
  2. Rather than use noble metal catalysts like Re or Au, we show the development and activity of a range of non-noble metal catalysts for the DODH reaction of 1,4-anhydroerythritol, a typical biomass-derived platform molecule, and demonstrate comparable yields of the target product. The new catalyst could be reused after calcination without loss of activity.
  3. An environmental impact assessment of the catalyst preparation and the final process could help guide the next steps.

Accessing secondary amine containing fine chemicals and polymers with an earth-abundant hydroaminoalkylation catalyst
M. Manßen, S. S. Scott, D. Deng, C. H. M. Zheng and L. L. Schafer.
Green Chem., 2023, 25, 2629-2639. DOI:10.1039/D3GC00011G

Green foundation
  1. We present a titanium-catalysed hydroaminoalkylation process, as a greener alternative to the industrially accepted hydroaminomethylation transformation, which relies on rhodium hydroformylation catalysts.
  2. Our Ti(NMe2)4/ligand system showed activity for an increased diversity of substrates, excellent regioselectivity, simple catalyst design, and quantifiable improvement on standard environmental assessment metrics. Compared to the best-in-class tantalum hydroaminoalkylation catalyst, our catalyst based on Ti(NMe2)4/ligand was shown by LCA to be less impactful in five out of nine categories for amine terminated polypropylene synthesis.
  3. This Ti(NMe2)4/ligand system could also be used for challenging postpolymerisation of macromolecular substrates, where this catalyst and process would offer a greener alternative.

Ultrasonic-assisted oxidation of cellulose to oxalic acid over gold nanoparticles supported on iron-oxide
P. N. Amaniampong, Q. T. Trinh, T. Bahry, J. Zhang and F. Jérôme.
Green Chem., 2022, 24, 4800-4811. DOI:10.1039/D2GC00433J

Green foundation
  1. The global market for oxalic acid was around 1340 thousand tons in 2022. Here we present a greener alternative to the harsh conditions regularly required in industry to overcome the recalcitrance of cellulose in chemical processing.
  2. We demonstrate that low frequency ultrasound induces the fragmentation of cellulose particles to facilitate the otherwise highly challenging, base-free oxidation of cellulose to oxalic acid. We show that ultrasonic conditions lead to partial fragmentation of cellulose particles, making it more reactive with the catalyst.
  3. Full elucidation and greater understanding of the role of ultrasonic conditions on the reaction mechanism is required.

Development of a solvent sustainability guide for the paints and coatings industry
L. Pilon, D. Day, H. Maslen, O. P. J. Stevens, N. Carslaw, D. R. Shaw and H. F. Sneddon.
Green Chem., 2024, Advance Article. DOI:10.1039/D4GC01962H

Green foundation
  1. The paints and coatings industry has increasingly been moving towards lower emissions and the nature of the solvents considered in future is anticipated to come under increasing scrutiny. A solvent sustainability guide is offered for the paints and coatings industry, considering solvents likely of interest in this sector, and considering criteria relevant to these applications.
  2. A range of solvents relevant to this sector were compared. While instances where like-for-like drop-in replacements can be identified are expected to be few, the guide allows ready identification of a range of greener or more sustainable solvents as possible start points for further formulation research.
  3. New solvent data continues to be collected, and regulations evolve, therefore, it is essential to only to use this guide in conjunction with reliable sources to obtain the most current information.

Selectivity switch by phase switch – the key to a high-yield furfural process
L. Ricciardi, W. Verboom, J.-P. Lange and J .Huskens
Green Chem., 2021, 23, 8079-8088.  DOI:10.1039/D1GC01752G

Green foundation
  1. Furfural is a versatile intermediate for biofuels and bio-based chemicals. We present a greener alternative to the industrial process that converts xylose-rich hydrolysate to furfural with higher yield.
  2. High xylose-to-furfural yield at and above approx. 90 mol%, becomes feasible with a variety of solvent combinations and phenylboronic acid concentrations. A conceptual process design for scaled-up furfural production is presented, where the produced furfural could be recovered from the system with modest losses of the solvents in the waste streams, and thus minimizing waste and maximizing recyclability.
  3. Additional research is needed to (1) finetune the selection of solvent and boronic acid to further minimize losses and toxicity/environmental risks, (2) validate the process concept and (3) deliver the information needed for designing the major pieces of equipment.

 

Article type: Perspectives
.
Energy crisis in Europe enhances the sustainability of green chemicals
A. Nabera, I.-R. Istrate, A. José Martín, J. Pérez-Ramírez and G. Guillén-Gosálbez.
Green Chem., 2023, 25, 6603-6611. DOI:10.1039/D3GC01053H

Green foundation
  1. Global production of ammonia and methanol are key elements of the chemical industry. Recent increases in energy prices in Europe have created a recent scenario where renewable options for both ammonia and methanol had the potential to outperform their fossil counterparts for six months (as of December 2021).
  2. If the European chemical industry can establish cost-competitive production routes of green ammonia and methanol, overcoming the primary obstacle to their implementation, then they have the opportunity to lead the transition and global movement towards environmentally responsible practices, while simultaneously reaping significant economic benefits in the long run.
  3. Global concerns regarding the environment and the price of sustainability means that identifying cost competitive low-carbon technologies are of special interest. With a coordinated effort from academia, industry, and policymakers, Europe can lead the grand transition towards more sustainable practices in the chemical industry.

Recent advances in the heterogeneous photochemical synthesis of C–N bonds
J. J. Wang, Y. Liu, X. Zong, A. Lei and Z. Sun.
Green Chem., 2023, 25, 5010-5023. DOI:10.1039/D3GC00931A

Green foundation
  1. Classical activation of C-N bonds with chemical processes can be made greener through photoactivation and the utilization of sunlight. We discuss the structure, characteristics, and reactivity of different types of heterogeneous photocatalysts for C–N coupling reactions.
  2. The synthesis and development of heterogeneous photocatalysts has progressed faster than testing for C-X activation. Herin, we summarize the most recent developments in photocatalysts, how they apply to C-X activation using C-N as an example, and then how reactions may be scaled up with a flow reactor.
  3. Many C-X activation reactions remain unresearched and providing greener alternatives to chemical reactions through the application of sunlight remains a high challenge. Scaling up photoactivated reactions to become industrially relevant would have a great impact.
Article type: Critical Reviews
.
Lignin for energy applications – state of the art, life cycle, technoeconomic analysis and future trends
A. Beaucamp, M. Muddasar, I. Saana Amiinu, M. Moraes Leite, M. Culebras, K. Latha, M. C. Gutiérrez, D. Rodriguez-Padron, F. del Monte, T. Kennedy, K. M. Ryan, R. Luque, M.-M. Titirici and Maurice N. Collins.
Green Chem., 2022, 24, 1445-1450. DOI: 10.1039/D2GC02724K

Green foundation
  1. Lignin is finding application in a remarkable array of materials for different energy applications from electrodes through to batteries. Here we assess the environmental impact of recent discoveries and the viability of future outcomes.
  2. Lignin is a by-product of several global industries. Research into its efficient processing and use is of wide interest, especially for certain use cases where more expensive or less green materials can be replaced.
  3. The emergence of economically viable biorefineries is a welcome step for the use of lignin for energy applications. However, for example, the depolymerisation processes are yet to be fully upscaled. For batteries, improvements in performance of lignin-based electrodes in full cell batteries should be the ultimate ambition.

Classic vs. C–H functionalization strategies in the synthesis of APIs: a sustainability comparison

F. Ferlin, G. Brufani, G. Rossinia and L. Vaccaro.
Green Chem., 2023, 25, 7916-7933. DOI:10.1039/D3GC02516K

Green foundation
  1. The research and discovery of efficient routes of synthesis for active pharmaceutical ingredients is an extraordinary challenge. We discuss and compare the relative sustainability and greenness of a range of functionalization strategies.
  2. There are significant and important demands to look at the environmental and safety impact of C–H functionalization methodologies from academia to industry. The adoption of green technologies and strategies for C–H functionalization adds to the transition to sustainable methodologies.
  3. Development of techno-economic studies on this subject would provide further opportunities for research and pave the way for the development of greener chemical methodologies.

Safe and sustainable chemicals and materials: a review of sustainability assessment frameworks
J. C. Caldeira, E. Abbate, C. Moretti, L. Mancinia and S. Sala.
Green Chem., 2024, 26, 7456-7477. DOI:10.1039/D3GC04598F

Green foundation
  1. We discuss how sustainability has been implemented in frameworks that are used to identify criteria for safe and sustainable by design chemicals and materials – particularly frameworks that consider more than one sustainability dimension (e.g., safety, environmental, social, and economic).
  2. This broad scope assessment of a range of frameworks from over 155 sources from academia, industry and government, allows for systematic comparison. By following these frameworks and studying the relative criteria, viable or alternative chemicals and materials can be screened before commercialization to avoid regrettable substitutions.
  3. Future studies to produce a comprehensive set of indicators for examining the sustainability of a chemical within proposals of frameworks from academia, governments, NGOs, or industry, are needed and also a well-defined method for assessing circularity.

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Article type: Tutorial Reviews
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Advances in catalytic dehydrogenation of ethanol to acetaldehyde
J. Pang, M. Yin, Pengfei Wu, X. Li, H. Li, M. Zheng and T. Zhang.
Green Chem., 2021, 23, 7902-7916. DOI: 10.1039/D1GC02799A

Green foundation
  1. We discuss greener methods to partially or totally replace fossil-based acetaldehyde. Owing to the wide range of applications of acetaldehyde, the catalytic conversion of ethanol to acetaldehyde has been extensively studied.
  2. Acetaldehyde is an important commodity with an annual production of over 106 tons. It is a key reagent or solvent for the production of a variety of industrial chemicals, such as peracetic acid, pentaerythritol and pyridine-based products. After years of study, the dehydrogenation of ethanol to acetaldehyde has developed to the point that it is a promising way to replace the fossil ethylene method, which uses Ag catalysts at a large scale even though these catalysts still face deactivation and regeneration issues.
  3. Although some interesting catalysts have been developed for oxidative and non-oxidative ethanol dehydrogenations, there remains significant work before these processes are commercially viable, especially over non-noble metal catalysts.

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