Final Report Summary - NOVCAT (Design of Novel Catalysis by Metal Complexes)
In view of concerns regarding the economy, environment and sustainable energy, there is a strong need for the development of new environmentally benign catalytic reactions which use abundant and inexpensive starting materials, generate no waste, proceed under mild conditions, use no toxic reagents and save energy. Our research has involved the design of such novel reactions based on new methodology for making and breaking chemical bonds developed by us, which involves pincer-type metal complexes as catalysts. In these complexes, the metal center cooperates with the pincer ligand bound to it in breaking bonds of incoming molecules and generating the desired products under mild conditions. In many of the newly developed processes hydrogen gas is evolved, while in other processes that we developed hydrogen gas is consumed, leading cleanly to unprecedented, industrially relevant methodology in chemical synthesis.
This research has also led to a fundamentally new approach to hydrogen storage, for transportation and stationary purposes, using a cheap and abundant organic liquid, aminoethanol, as a hydrogen carrier, rather then using compressed hydrogen gas which is of low energy density and potentially unsafe.
In addition, our interdisciplinary research has generated fundamentally new understanding in the areas of activation of chemical bonds, catalytic design, and transformations in the coordination sphere of metal complexes. This understanding has recently led to novel reactivity and catalysis by complexes based on the abundant and inexpensive metals iron and cobalt, which bodes well for further development of novel catalysis based on these metal complexes.
Several PhD students and Post Doctoral Fellows were trained within the framework of this program and later found positions in academic institutions and in industry in Israel, Europe and other countries. Some specific results of our research are:
Activation of multiple bonds by metal-ligand cooperation was also discovered, including the activation of C=O bonds of CO2, and CN triple bonds of nitriles by de-aromatized pincer complexes, opening a new direction in catalysis.
Based on our new metal-ligand cooperation concept, several synthetically useful new reactions catalyzed by various pincer complexes were developed, with no waste generation, such as (a) synthesis of peptides and pyrazines from β-aminoalcohols (b) one-step synthesis of pyrroles by dehydrogenative coupling of β-aminoalcohols with ketones, providing one of the best methods for preparation of these important compounds (c) synthesis of amides from esters and amines under neutral conditions with the only by product being H2 (d) synthesis of polyamides, including functionalized ones, by coupling of diols with diamines, (e) direct catalytic olefination of alcohols with sulfones (f) transformation of alcohols to carboxylic acid salts using just water as the oxidant, generating H2 (g) conversion of cyclic amines to lactams and H2 using no oxidant apart from water.
Catalysis by iron and cobalt pincer complexes of industrially important reactions was achieved, including (a) the most efficient hydrogenation of ketones and aldehydes, rivalling the hydrogenation efficiency of noble metals (b) first iron-catalyzed hydrogenation of esters (c) hydrogenation of CO2 to formate salts (d) the first iron catalyzed semi-hydrogenation of alkynes to E-alkenes (e) the first ester hydrogenation catalyzed by a cobalt complex.
Catalytic hydrogenation of organic carbonates, carbamates and ureas was accomplished for the first time. Since these compounds are available from CO2 (and CO), this discovery presents a mild, two step process for the highly desirable hydrogenation of CO2 (and CO) to methanol fuel.
A process for the capture of CO2 at one atmosphere by aminoethanol derivatives, forming cyclic carbamates, and their in-situ hydrogenation, was developed, unprecedently forming methanol directly from sequestered CO2.
A novel hydrogen storage process, based on dehydrogenation of aminoethanol, forming a dipeptide, which can be hydrogenated back to aminoethanol using the same catalyst, was developed. The potentially high hydrogen capacity, low cost of ethanolamine and its compatibility with existing infrastructure make it an attractive, safe system for hydrogen storage and generation when needed.
This research has also led to a fundamentally new approach to hydrogen storage, for transportation and stationary purposes, using a cheap and abundant organic liquid, aminoethanol, as a hydrogen carrier, rather then using compressed hydrogen gas which is of low energy density and potentially unsafe.
In addition, our interdisciplinary research has generated fundamentally new understanding in the areas of activation of chemical bonds, catalytic design, and transformations in the coordination sphere of metal complexes. This understanding has recently led to novel reactivity and catalysis by complexes based on the abundant and inexpensive metals iron and cobalt, which bodes well for further development of novel catalysis based on these metal complexes.
Several PhD students and Post Doctoral Fellows were trained within the framework of this program and later found positions in academic institutions and in industry in Israel, Europe and other countries. Some specific results of our research are:
Activation of multiple bonds by metal-ligand cooperation was also discovered, including the activation of C=O bonds of CO2, and CN triple bonds of nitriles by de-aromatized pincer complexes, opening a new direction in catalysis.
Based on our new metal-ligand cooperation concept, several synthetically useful new reactions catalyzed by various pincer complexes were developed, with no waste generation, such as (a) synthesis of peptides and pyrazines from β-aminoalcohols (b) one-step synthesis of pyrroles by dehydrogenative coupling of β-aminoalcohols with ketones, providing one of the best methods for preparation of these important compounds (c) synthesis of amides from esters and amines under neutral conditions with the only by product being H2 (d) synthesis of polyamides, including functionalized ones, by coupling of diols with diamines, (e) direct catalytic olefination of alcohols with sulfones (f) transformation of alcohols to carboxylic acid salts using just water as the oxidant, generating H2 (g) conversion of cyclic amines to lactams and H2 using no oxidant apart from water.
Catalysis by iron and cobalt pincer complexes of industrially important reactions was achieved, including (a) the most efficient hydrogenation of ketones and aldehydes, rivalling the hydrogenation efficiency of noble metals (b) first iron-catalyzed hydrogenation of esters (c) hydrogenation of CO2 to formate salts (d) the first iron catalyzed semi-hydrogenation of alkynes to E-alkenes (e) the first ester hydrogenation catalyzed by a cobalt complex.
Catalytic hydrogenation of organic carbonates, carbamates and ureas was accomplished for the first time. Since these compounds are available from CO2 (and CO), this discovery presents a mild, two step process for the highly desirable hydrogenation of CO2 (and CO) to methanol fuel.
A process for the capture of CO2 at one atmosphere by aminoethanol derivatives, forming cyclic carbamates, and their in-situ hydrogenation, was developed, unprecedently forming methanol directly from sequestered CO2.
A novel hydrogen storage process, based on dehydrogenation of aminoethanol, forming a dipeptide, which can be hydrogenated back to aminoethanol using the same catalyst, was developed. The potentially high hydrogen capacity, low cost of ethanolamine and its compatibility with existing infrastructure make it an attractive, safe system for hydrogen storage and generation when needed.