CENTC Undergraduate Summer Research Program Accepting Applications

Applications are now available for the CENTC Undergraduate Summer Research Program. Undergraduate fellowships are available to conduct research at a choice of CENTC’s 12 locations during the summer of 2011. The program is 10 weeks long, running from June 13, 2011 through August 19, 2011. Fellows will receive a stipend and compensation for travel and housing. For more information and to download an application, visit:
http://depts.washington.edu/centc/education_ur.htm

Melanie Sanford named AAAS Fellow

CENTC researcher, Professor Melanie Sanford, has been elected as a Fellow of the American Association for the Advancement of Science (AAAS). AAAS recognizes Fellows for their contributions to science and technology. Prof. Sanford is honored for distinguished contributions to the fields of organic, organometallic, and inorganic chemistry, particularly the development and mechanistic study of new transition metal catalyzed reactions.

Read the full list of elected AAAS Fellows.

For more information about Melanie Sanford and her research, please visit her faculty page and research group website.

A novel route to key aromatics

CENTC researchers have found a new way to create aromatic compounds from straight chains of hydrocarbons by using an iridium-based catalyst. The reaction takes place at much lower temperatures than the conventional way of producing aromatic molecules from hydrocarbon chains and with a much higher degree of control over the end products, some of which are difficult or impossible to obtain by standard routes.

Aromatics are key building block molecules for the chemical industry. They are currently produced mainly by a process of catalytic reforming of petroleum feedstocks, which is carried out at temperatures of around 500°C, and produces a complex mixture of molecules that need to be subsequently separated.

Now a team led by Alan Goldman of Rutgers University and Maurice Brookhart of the University of North Carolina at Chapel Hill has shown that it is possible to produce aromatic molecules from their straight-chain counterparts, n-alkanes, at temperatures several hundred degrees lower than other methods.

Pincer-ligated iridium complex
(Photo: Nature Chem.)

The key to the process is a pincer-ligated iridium complex that acts as a homogeneous catalyst. Here, iridium is clamped by three arms contained within a phosphine-based cage. 'This makes it very stable, allowing it to be heated to the temperatures we need, close to 200°C,' says Brookhart.

When an alkane is introduced to the catalyst, the iridium inserts itself between a C-H bond and pries the hydrogen away, presenting it to a hydrogen acceptor - in this case t-butylethylene. This results in the generation of a double bond within the carbon chain. The process is repeated twice more, creating a triene, which then undergoes cyclisation followed by loss of an additional equivalent of hydrogen to produce the aromatic product.

Different aromatics are produced depending on the number of carbons in the starting alkane. Many of the subsequent products are difficult or impossible to produce by other means says Goldman. 'For example if you start with decane, you end up with linear alkyl aromatics that are normally impossible to obtain with conventional routes, which combine olefins and lighter aromatics. Alternatively, if you tried to make these products from alkanes using current heterogenous routes you would get extensive bond breaking of the carbon chains, whereas we get mostly compounds with the same carbon number as our starting material.'

R. Ahuja et al, Nature Chem., 2010, DOI: 10.1038/nchem.946