Carbenes: New molecules have wide applications

Oct 22, 2009
This is the molecular structure of the C5-Abnormal N-Heterocyclic Carbene (blue: nitrogen atoms; violet: abnormal carbene carbon atom; gray: normal carbon atoms). Credit: Bertrand lab, UC Riverside.

Researchers at the University of California, Riverside have created in the laboratory a class of carbenes, highly reactive molecules, used to make catalysts - substances that facilitate chemical reactions. Until now, chemists believed these carbenes, called "abnormal N-heterocyclic carbenes" or aNHCs, were impossible to make.

Carbenes are made up of unusual carbon atoms and are usually unstable in nature. They attach themselves to metals to form metal-carbene complexes that serve as efficient catalysts used widely in the pharmaceutical industry.

The metal-carbene complexes are formed in two ways: (a) the complex is created in one step, without first preparing carbene independently, and (b) a and an independent carbene are brought together to make the complex.

Most often the metal used in a metal-carbene complex is rhodium, gold, platinum or - all of which are very expensive and, in some cases, even toxic. To bring down the cost of catalysts, when possible, carbenes are used independently (without metals) in many chemical reactions.

Until now, aNHCs have been used as only metal-carbene complexes, never independently. Chemists had assumed that aNHCs cannot exist freely, which made them impossible to make.

Now UC Riverside's Guy Bertrand, a distinguished professor of chemistry, and colleagues have challenged that assumption by successfully creating aNHCs that are metal-free and can be used to make any desired complex.

"Many chemical species are believed to be unstable because they do not obey the rules we learned at school, and consequently nobody tries to make them," said Bertrand, who led the research project. "The role of scientists, however, is to challenge former hypotheses. That is just what we did in the case of the aNHCs, and we were successful.

"The aNHCs are stable at both in the and in solution, which means their application as metal-free catalysts is extremely wide, greatly benefiting industry by making possible scores of new ."

Results of the study appear in the Oct. 23 issue of Science.

"This study, reporting the synthesis and characterization of an entirely different class of metal-free NHCs, could open new horizons and have a huge impact on the field of catalysis," said John Schwab, who oversees organic synthesis grants at the National Institutes of Health's National Institute of General Medical Sciences. "The potential applications to drug discovery and manufacture are exciting, since catalytic processes can help keep costs in check and be environmentally friendly, to boot."

Bertrand is interested in making aNHCs commercially available. "We hope many chemists in the world will use these carbenes and find some new applications," he said.

The UCR Office of Technology Commercialization has filed a patent application on the technology and is currently seeking partners in industry interested in developing the technology commercially.

Source: University of California - Riverside (news : web)

Explore further: Researchers open possible avenue to better electrolyte for lithium ion batteries

add to favorites email to friend print save as pdf

Related Stories

Chemists identify organic molecules that mimic metals

Apr 19, 2007

A limitation in using hydrogen as a fuel in hydrogen-powered vehicles is the difficulty involved in storing it in a cost-effective and convenient manner. While it is possible to store hydrogen using metals, the resulting ...

Interstellar chemical tamed in the lab at UCR

Apr 13, 2006

Chemists at the University of California, Riverside have created in the laboratory a type of molecules thought to exist only in interstellar space, which may have valuable applications in chemical industry.

New Direction for Hydrogen Atom Transfers

Oct 19, 2005

In the annals of chemistry, there are many examples of hydrogen atoms moving from metals to carbon atoms. But no one has ever directly observed the reverse reaction — hydrogen atoms moving from carbon to a metal — until ...

Recommended for you

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.