New Industrial Catalysts Developed – Promising 'Greener', Cheaper, Safer Drugs And Perfumes

perfume bottle (photo: Angela Andriot)

Chemists at the University of Toronto have developed a new class of eco-friendly metal catalysts for use in a variety of industries that can viably replace the rare and expensive metals currently in use.

Metal catalysts are necessary to produce the basic chemical structures (e.g., amines and alcohols) which are the basis of everything from pharmaceuticals and flavorings to perfumes and pigments. The new catalysts — based on iron oxide — promise cheaper and safer chemical processes. Further, because iron is more biologically compatible and is the fifth most abundant element on Earth, these new catalysts are considered ‘greener’ than such traditional rare metal catalysts as ruthenium, rhodium, palladium and platinum (which are also quite toxic).

In making a variety of chemical structures as precursors to larger, industrially useful chemicals,  chemists require “transition” metals to trigger a process called hydrogenation. Substituting an iron oxide (Fe{II}) based template for these rare metals resulted in highly efficient iron complexes which exhibited catalytic abilities (i.e., molecular yields, turnover frequencies) that were competitive with, and, in many cases, surpassed these conventional catalysts.

Reporting in the 29 November issue of Science, principal investigator Robert Morris, stated:

“We found a way to make the ferrous form of iron behave in a catalytic process much more efficiently than a precious metal. We did this by finding molecules containing nitrogen, phosphorus, carbon and hydrogen, that bond to, and enhance, the reactivity of iron.”

The process developed by the U of T researchers was a validation of an earlier hypothesis that saturated ligands (types of stable, metal-based, binding molecules) of a particular chemical “species” could be used to activate iron and thus catalyze the “asymmetric reduction” (involving the partial donation of hydrogen ions) of certain chemical bonds to form “enantiopure alcohols and amines.”

Other research teams (also reporting their results in the same issue of Science), such as  Jagadeesh et al, are working with iron-oxide particles surrounded by a “nitrogen-doped carbon layer” to efficiently catalyze the hydrogenation of nitroarenes, the reduction of which leads to chemical “building blocks” called anilines which are used in the agrochemical industry, as well as in dyes and pharmaceuticals.

Professor Morris sums up the current “green” catalyst revolution in the chemical industry:

“There is a research effort world-wide to make chemical processes more sustainable and green by replacing the rare, expensive and potentially toxic elements used in hydrogenation, catalytic converters in cars, fuel cells for the efficient conversion of chemical energy into electricity, and silicone coatings, with abundant ions such as iron. Iron is about 10,000 times cheaper to obtain than ruthenium. And less than 200 metric tons of platinum-type metals are mined in the world every year, not all of it can be recycled after use, it is not essential to life, and it can be toxic.”

All told, these new, environmentally “benign” catalysts seem to be good news for the planet’s (unavoidable) chemical future.

And, the  move towards marketplace adoption has already begun: the Canadian sustainable technology incubator GreenCentre Canada (a funding partner in this research along with the Natural Sciences and Engineering Research Council of Canada) is currently pursuing the commercialization of the new iron catalysts.

Top Image: (A collection of glass perfume bottles: Vetiver Aromatics); credit: Angela Andriot ; CC – By – SA 3.0



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