UK scientists have come up with a green method for synthesising amides, a fundamental reaction in the pharmaceutical industry, using a cheap and readily available material found lying around in labs.

James Clark and co-workers from the University of York developed a heterogeneous catalyst from silica gel, which is usually used as the stationary phase in column chromatography. They heated the silica gel to 700 °C to activate it then used it in a reaction to combine a carboxylic acid and an amine to make an amide. The only by-product was water, making the method cheaper, cleaner and less toxic than existing procedures. The catalyst remains active for a long time too, even after exposure to the atmosphere, and can be filtered for reuse.

Amides have been synthesised in various ways over the years, but the methods are 'hazardous, complex and expensive', says Clark. 'Amide synthesis has been highlighted by the pharmaceutical industry as one of the most important targets for greening.' 

Peter Dunn at Pfizer, Kent, UK, who is part of the industry group that identified amide synthesis as a prime target for greening, says: 'What I find most interesting about this research is that the authors have used standard silica, which can be found in any synthetic chemistry laboratory. They took a material that was just lying around in the lab and discovered that it can be easily converted to an effective catalyst for this important transformation.'

'Green chemistry should always challenge the more traditional chemistry community to reconsider established practices and to apply its skills and intelligence to design greener and more sustainable processes and products,' says Clark. 'We want to extend this particular type of chemistry to as wide a range of substrates and products as possible and then see where else we can apply the "simple is beautiful" and "complex isn't clever" philosophies.'  
 
Mary Badcock

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