Periodic Reporting for period 1 - SiTi-CAT (Well-Defined Silica-Supported Titanium Catalysts for Introducing Nitrogen Functional Groups)
Berichtszeitraum: 2022-11-14 bis 2024-11-13
Amines are commercially valuable nitrogen-containing chemicals that are essential to modern life due to their use in pharmaceuticals, agrochemicals and polymers (global market USD 16.6 billion). However, existing routes to make amines on large scale are inefficient and expensive largely due to the wasteful by-products that are also made. Green routes to amines called hydroamination and hydroaminoalkylation have been developed in universities but are not yet viable on large scale. These are 100% atom efficient reactions and so by definition do not produce any by-products. A metal "catalyst" is required for these reactions to occur. Although traditional catalysts contain expensive precious metals, state-of-the-art catalysts contain titanium, which is abundant in the Earth's crust, and thus environmentally and economically advantageous. Currently these catalysts are not transferrable into large scale processes due to the high costs of removing the catalyst to recycle it and purify the products.
We need to adapt state-of-the-art titanium catalysts for the efficient and selective production of amines to be economically viable in industrial processes. Principally, this involves changing the state of the catalyst. By affixing the catalysts onto a solid support, they can be easily and cheaply removed by filtration. However, to do this, we need to develop methods to attach the catalysts to the solid supports without significantly changing their structure.
This project will develop industrially viable catalysts for making amines by affixing titanium catalysts for hydroamination and hydroaminoalkylation onto a solid support. It will blend the disciplines of chemical synthesis, catalysis, and surface organometallic chemistry by using the expertise of researchers and specialist facilities in Canada and France. This project will transform green processes to manufacture amines from academic research into industrial routes. Transfer of this technology into industry would decrease the cost and increase the range of amines available on a large scale. Knowledge and key skills will be shared between European and Canadian researchers, resulting in a synergic partnership impacting academic and industrial fields.
We need to adapt state-of-the-art titanium catalysts for the efficient and selective production of amines to be economically viable in industrial processes. Principally, this involves changing the state of the catalyst. By affixing the catalysts onto a solid support, they can be easily and cheaply removed by filtration. However, to do this, we need to develop methods to attach the catalysts to the solid supports without significantly changing their structure.
This project will develop industrially viable catalysts for making amines by affixing titanium catalysts for hydroamination and hydroaminoalkylation onto a solid support. It will blend the disciplines of chemical synthesis, catalysis, and surface organometallic chemistry by using the expertise of researchers and specialist facilities in Canada and France. This project will transform green processes to manufacture amines from academic research into industrial routes. Transfer of this technology into industry would decrease the cost and increase the range of amines available on a large scale. Knowledge and key skills will be shared between European and Canadian researchers, resulting in a synergic partnership impacting academic and industrial fields.
The work conducted during this project mainly concerned developing the methods to make the solid-affixed catalysts. The solid support used was silica (SiO2) since this is the most used and developed in previous studies. To mimic the titanium catalysts for hydroamination and hydroaminoalkylation developed in academia, it is necessary to mimic the entire catalyst structure, including the "ligands", which are peripheral chemical structures and attach to and support the metal. The group of Prof Laurel Schafer have developed ligands with nitrogen and oxygen atoms that bind to the titanium and determine the high selectivity and activity in hydroamination and hydroaminoalkylation catalysis.
To attach the ligands to the surface, we made special silicas with chemical motifs such as iodine atoms that we could then manipulate chemically to transform into the N,O-ligands we targeted. This builds on work by Dr Chloé Thieuleux. We attempted several synthetic routes, testing each route in solution and then on several different silica starting materials. Some hydroaminoalkylation catalysis was also attempted.
To attach the ligands to the surface, we made special silicas with chemical motifs such as iodine atoms that we could then manipulate chemically to transform into the N,O-ligands we targeted. This builds on work by Dr Chloé Thieuleux. We attempted several synthetic routes, testing each route in solution and then on several different silica starting materials. Some hydroaminoalkylation catalysis was also attempted.
Although we designed the synthetic routes and each chemical transformation we planned to perform on the silica surfaces in solution, when performing them on the silica surface, the yields were very poor. We found the reagents stuck to the silica surfaces and did not react. Thus, we determined that such tests are nor always useful in planning synthetic routes to the ligands we wanted. We also found that the nature of the silica surface impacts reactivity. In spite of our best efforts and many attempted synthetic routes, we could not achieve the successful affixation of N,O-ligated titanium catalysts to silica for hydroamination and hydroaminoalkylation catalysis.
We attempted hydroaminoalkylation catalysis using titanium catalysts attached to the silica using amine ligands, but the yields were poor. We determined this was due to poor thermal stability of the catalysts.
Further research should be dedicated to developing methodology to install a wider range of ligand motifs onto surfaces. This could include changing the surface, investigating "protecting groups" that prevent side reactions with the silica surface, or using different spacers or tethers between the surface and chemical functionality.
We attempted hydroaminoalkylation catalysis using titanium catalysts attached to the silica using amine ligands, but the yields were poor. We determined this was due to poor thermal stability of the catalysts.
Further research should be dedicated to developing methodology to install a wider range of ligand motifs onto surfaces. This could include changing the surface, investigating "protecting groups" that prevent side reactions with the silica surface, or using different spacers or tethers between the surface and chemical functionality.