Catalysis using earth abundant and environmentally benign s-block metals
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Chemistry
Abstract
Project background (identification of the problem and its importance and relevance to sustainability)
There is an irrefutable need for the chemical industry to become more sustainable. Catalysis is fundamental to the worlds chemical industry, and catalysis-based synthesis accounts for around 90 % of all current processes. For many years, organometallic complexes of precious noble metals have been at the heart of homogeneous catalysis. These elements are expensive and their geological paucity results in particular sensitivity to global supply restrictions. Despite the near ubiquitous employment of catalytic reagents being a positive step towards realising the 12 principles of green chemistry, the exhaustive use of these rare, expensive and often toxic metals is in direct contradiction to many of the other key principles.
In response to these issues, there have been major global efforts towards chemical synthesis using complexes of earth abundant and benign metals as replacements for traditional catalytic methods. The lighter s-block metals are experiencing a significant amount of attention as ideal replacements, particularly sodium, potassium, magnesium and calcium, due to their high relative abundance in the Earth's crust. These metals are readily available, cheap and environmentally benign. Such complexes have shown clear promise in catalysing a range of reactions, affording products and selectivities not seen for traditional catalysts. Thus, they represent clear potential to create sustainable, economic and green catalytic frameworks.
Proposed solution and methodology
Recent research in the Kays group has shown that chelating and pincer ligands can be used to stabilise complexes of cheap, abundant and environmentally benign alkali and alkaline earth metals in high yields, which can act as efficient highly active catalysts for amine-borane dehydrocoupling and hydroelementation reactions.1,2 The development of this catalysis, in particular for the extension of this chemistry to new substrates and organic transformations, is essential if homogeneous catalysts based on the s-block are to become broadly applicable and widely adopted. As a result, this proposal suggests further design and development of robust s-block complexes for use as catalysts in a wide variety of reactions in the valorisation of small molecules for the synthesis of new chemicals. This project will design and develop active, stable and robust magnesium complexes, which will be investigated for their use as precatalysts in a range of reactions such as hydroelementation, cross-coupling and dehydrocoupling of small molecules. First, these catalysts will be employed in the hydroboration of both simple and complex nitriles to provide a route to key synthetic intermediates with labile N-B bonds which can be conveniently transformed into various functionalities such as amines, alcohols and halides. Preparation of these compounds will also be demonstrated within this work. We will also investigate how to make these catalytic reactions more sustainable and environmentally benign, through use of green solvents and optimisation of the reaction conditions. In parallel with this, the investigation of the mechanisms of these reactions through detailed kinetic analyses will inform catalyst improvements and future design. This chemistry will be extended to a wide variety of substrates such as inter- and intramolecular hydroelementation reactions, other multiple bonds, investigating the functional group tolerance of these catalysts and catalytic processes in conjunction with the applicability of these reactions in organic synthesis.
There is an irrefutable need for the chemical industry to become more sustainable. Catalysis is fundamental to the worlds chemical industry, and catalysis-based synthesis accounts for around 90 % of all current processes. For many years, organometallic complexes of precious noble metals have been at the heart of homogeneous catalysis. These elements are expensive and their geological paucity results in particular sensitivity to global supply restrictions. Despite the near ubiquitous employment of catalytic reagents being a positive step towards realising the 12 principles of green chemistry, the exhaustive use of these rare, expensive and often toxic metals is in direct contradiction to many of the other key principles.
In response to these issues, there have been major global efforts towards chemical synthesis using complexes of earth abundant and benign metals as replacements for traditional catalytic methods. The lighter s-block metals are experiencing a significant amount of attention as ideal replacements, particularly sodium, potassium, magnesium and calcium, due to their high relative abundance in the Earth's crust. These metals are readily available, cheap and environmentally benign. Such complexes have shown clear promise in catalysing a range of reactions, affording products and selectivities not seen for traditional catalysts. Thus, they represent clear potential to create sustainable, economic and green catalytic frameworks.
Proposed solution and methodology
Recent research in the Kays group has shown that chelating and pincer ligands can be used to stabilise complexes of cheap, abundant and environmentally benign alkali and alkaline earth metals in high yields, which can act as efficient highly active catalysts for amine-borane dehydrocoupling and hydroelementation reactions.1,2 The development of this catalysis, in particular for the extension of this chemistry to new substrates and organic transformations, is essential if homogeneous catalysts based on the s-block are to become broadly applicable and widely adopted. As a result, this proposal suggests further design and development of robust s-block complexes for use as catalysts in a wide variety of reactions in the valorisation of small molecules for the synthesis of new chemicals. This project will design and develop active, stable and robust magnesium complexes, which will be investigated for their use as precatalysts in a range of reactions such as hydroelementation, cross-coupling and dehydrocoupling of small molecules. First, these catalysts will be employed in the hydroboration of both simple and complex nitriles to provide a route to key synthetic intermediates with labile N-B bonds which can be conveniently transformed into various functionalities such as amines, alcohols and halides. Preparation of these compounds will also be demonstrated within this work. We will also investigate how to make these catalytic reactions more sustainable and environmentally benign, through use of green solvents and optimisation of the reaction conditions. In parallel with this, the investigation of the mechanisms of these reactions through detailed kinetic analyses will inform catalyst improvements and future design. This chemistry will be extended to a wide variety of substrates such as inter- and intramolecular hydroelementation reactions, other multiple bonds, investigating the functional group tolerance of these catalysts and catalytic processes in conjunction with the applicability of these reactions in organic synthesis.
Planned Impact
This CDT will have a positive impact in the following areas:
PEOPLE. The primary focus is people and training. Industry needs new approaches to reach their sustainability targets and this is driving an increasing demand for highly qualified PhD graduates to lead innovation and manage change in the area of chemicals production. CDT based cohort training will provide industry ready scientists with the required technical competencies and drive to ensure that the sector retains its lead position in both innovation and productivity. In partnership with leading chemical producers and users, we will provide world class training to satisfy the changing needs of tomorrow's chemistry-using sector. Through integrated links to our Business School we will maximise impact by delivering dynamic PhD graduates who are business aware.
ECONOMY. Sustainability is the major issue facing the global chemical industry. Not only is there concern for our environment, there is also is a strong economic driver. Shareholders place emphasis on the Dow Jones Sustainability Index that tracks the performances of the sector and engenders competition. As a result, major companies have set ambitious targets to lower their carbon footprints, or even become carbon neutral. GSK CEO Sir Andrew Witty states that "we have a goal to reduce our emissions and energy use by 45% compared with 2006 levels on a per unit sales basis... " Our CDT will help companies meet these challenges by producing the new chemistries, processes and people that are the key to making the step changes needed.
SOCIETY. The diverse range of products manufactured by the chemical-using industries is vital to maintain a high quality of life in the UK. Our CDT will have a direct impact by ensuring a supply of people and new knowledge to secure sustainability for the benefit of all. The role of chemistry is often hidden from the public view and our CDT will provide a platform to show chemical sciences in a positive light, and to demonstrate the importance of engineering and applications across biosciences and food science.
The "green and sustainable" agenda is now firmly fixed in the public consciousness, our CDT will be an exemplar of how scientists and engineers are providing solutions to very challenging scientific and technical problems, in an environmentally benign manner, for the benefit of society. We will seek sustainable solutions to a wide range of problems, whilst working in sustainable and energy efficient facilities. This environment will engender a sustainability ethos unique to the UK. The CNL will not only serve as a base for the CDT but also as a hub for science communication.
Public engagement is a crucial component of CDT activities; we will invite input and discussion from the public via lectures, showcases and exhibition days. The CNL will form a hub for University open days and will serve as a soft interface to give school children and young adults the opportunity to view science from the inside. Through Dr Sam Tang, public awareness scientist, we have significant expertise in delivering outreach across the social spectrum, and she will lead our activities and ensure that the CDT cohorts engage to realise the impact of science on society. Martyn Poliakoff, in his role as Royal Society Foreign Secretary, will ensure that our CDT dovetails with UK science policy.
KNOWLEDGE. In addition to increasing the supply of highly trained people, the results of the PhD research performed in our CDT will have a major impact on knowledge. Our student cohorts will tackle "the big problems" in sustainable chemistry, and via our industrial partners we will ensure this knowledge is applied in industry, and publicised through high level academic outputs. Our knowledge-based activities will drive innovation and economic activity, realising impact through creation of new jobs and securing the future.
PEOPLE. The primary focus is people and training. Industry needs new approaches to reach their sustainability targets and this is driving an increasing demand for highly qualified PhD graduates to lead innovation and manage change in the area of chemicals production. CDT based cohort training will provide industry ready scientists with the required technical competencies and drive to ensure that the sector retains its lead position in both innovation and productivity. In partnership with leading chemical producers and users, we will provide world class training to satisfy the changing needs of tomorrow's chemistry-using sector. Through integrated links to our Business School we will maximise impact by delivering dynamic PhD graduates who are business aware.
ECONOMY. Sustainability is the major issue facing the global chemical industry. Not only is there concern for our environment, there is also is a strong economic driver. Shareholders place emphasis on the Dow Jones Sustainability Index that tracks the performances of the sector and engenders competition. As a result, major companies have set ambitious targets to lower their carbon footprints, or even become carbon neutral. GSK CEO Sir Andrew Witty states that "we have a goal to reduce our emissions and energy use by 45% compared with 2006 levels on a per unit sales basis... " Our CDT will help companies meet these challenges by producing the new chemistries, processes and people that are the key to making the step changes needed.
SOCIETY. The diverse range of products manufactured by the chemical-using industries is vital to maintain a high quality of life in the UK. Our CDT will have a direct impact by ensuring a supply of people and new knowledge to secure sustainability for the benefit of all. The role of chemistry is often hidden from the public view and our CDT will provide a platform to show chemical sciences in a positive light, and to demonstrate the importance of engineering and applications across biosciences and food science.
The "green and sustainable" agenda is now firmly fixed in the public consciousness, our CDT will be an exemplar of how scientists and engineers are providing solutions to very challenging scientific and technical problems, in an environmentally benign manner, for the benefit of society. We will seek sustainable solutions to a wide range of problems, whilst working in sustainable and energy efficient facilities. This environment will engender a sustainability ethos unique to the UK. The CNL will not only serve as a base for the CDT but also as a hub for science communication.
Public engagement is a crucial component of CDT activities; we will invite input and discussion from the public via lectures, showcases and exhibition days. The CNL will form a hub for University open days and will serve as a soft interface to give school children and young adults the opportunity to view science from the inside. Through Dr Sam Tang, public awareness scientist, we have significant expertise in delivering outreach across the social spectrum, and she will lead our activities and ensure that the CDT cohorts engage to realise the impact of science on society. Martyn Poliakoff, in his role as Royal Society Foreign Secretary, will ensure that our CDT dovetails with UK science policy.
KNOWLEDGE. In addition to increasing the supply of highly trained people, the results of the PhD research performed in our CDT will have a major impact on knowledge. Our student cohorts will tackle "the big problems" in sustainable chemistry, and via our industrial partners we will ensure this knowledge is applied in industry, and publicised through high level academic outputs. Our knowledge-based activities will drive innovation and economic activity, realising impact through creation of new jobs and securing the future.
