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Cheaper and solvent-free chemistry processes, central for mining, pharmaceutical and other industries will be better understood after scientists for the first time, observed chemical reactions in a mechanical mill in situ and in real time. Solvents are widely used in the chemical industry but are a major environmental and safety concern. An energy-efficient alternative is to use high-frequency milling to drive reactions, mixing solid reactants in a chemical mill.  Understanding the mechanisms of these processes will allow the reactions to be improved and new materials to be made. The problem is that milling of this kind is achieved by the intense impact of steel balls in a rapidly moving jar which hinders the direct observation of the underlying chemistry. Results in Nature Chemistry this week (2 December 2012) show how this has been made possible.

An international team led by by Tomislav Friščić, a Research Fellow at the University of Cambridge at the time, but now an Assistant Professor at McGill University in Canada, was able to study mechanochemical reactions in perspex, steel or aluminium jars by using highly penetrating X-rays at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The team, also including Patrick Beldon and Ana Belenguer from the University of Cambridge, used a milling device adapted in-house at Cambridge. The measurements recorded surprisingly rapid transformations and also enabled in situ monitoring of product nanoparticles. In the past it has been difficult to study what happens during these mechanically-driven reactions in closed steel jars. Using ESRF to penetrate the reaction vessel allowed reactions to be studied as they occurred.

Patrick Beldon said: “Previous attempts to study the rates of grinding reactions relied on stopping the grinding at various times, then taking the material out to analyse the products. Unfortunately, the reaction can continue even once the grinding has stopped so you are never sure how your material is changing while you’re handling it. By looking at the reaction while it is happening, we get a much clearer picture of what is going on. This technique should be applicable to any grinding reaction so we’re hoping it will allow people to discover and understand new reactions”.

As well as having the potential to make industrial chemistry cheaper and more environmentally friendly, the results could also change the way that chemists make and explore new materials.

For more details including the available images please see the ESRF’s website (link opens in a new window)

STFC manages the UK subscription to ESRF, allowing UK scientists access to the facility.

Paper reference:

T. Friščić et al.: Real-time and in situ monitoring of mechanochemical milling reactions, Nature Chemistry Advanced Online Publication, DOI 10.1038/NCHEM.1505

Additional information:

The international team of scientists was led by Tomislav Friščić of McGill University (Canada) in collaboration with Ivan Halasz from the University of Zagreb (Croatia), scientists from the University of Cambridge (UK), Max-Planck-Institute for Solid State Research in Stuttgart (Germany) and the European Synchrotron Radiation Facility (ESRF) in Grenoble (France).

Press officer contacts

Lucy Stone, STFC, UK: tel: 01235 445627

Claus Habfast, ESRF, Grenoble: cell +33 666 662 384

Chris Chipello, McGill, Canada:  Tel +1 514 398 4201