Lead-free catalyst opens up new reaction to pharma
The first two catalysts in the firm’s NanoSelect range – LF 100 and LF 200 – can be used in place of lead-based Lindlar catalysts, commonly used in hydrogenation reactions in the fine chemicals industry.
A Lindlar catalyst is a heterogeneous catalyst that consists of palladium deposited on calcium carbonate and treated with various forms of lead.
They are generally used in the hydrogenation of alkynes to convert carbon-carbon triple bonds to double bonds and form alkanes. The lead is used to slow down the reaction to avoid further hydrogenation to a carbon-carbon single bond and the creation of an alkene.
“Lindlar catalysts are widely used in the production of fine chemicals, but are not used in pharmaceuticals because of the risk that lead contamination could find its way into the active pharmaceutical ingredient,” said Dr Hans Donkervoort, global product technology manager, specialty and fine chemicals catalysts developments, at BASF.
The reactions is commonly used in the flavours and fragrances sector. Alkane ketones are used in perfumery, for example, alkyne hydrogenation is also an important step in the commercial organic synthesis of vitamin A.
The new lead-free products from BASF make this efficient and cost-effective synthetic route open to pharma, and are particularly useful when the aim is to achieve a high selectivity for the cis form of the alkali, said Donkervoort in an interview at CPhI.
“Costs are reduced by cutting the amount of expensive precious metals used in the catalyst,” he said. “A Lindlar catalyst has around 5 per cent palladium, but with our NanoSelect products that is reduced to just 0.5 per cent.”
Based on a 5 per cent palladium content, $900 is added to the total cost for every kilogramme of Lindlar catalyst used during hydrogenation, according to BASF.
NanoSelect LF 100 and LF 200 are described as unimodal metal particles – with a typical size of just 7nm which greatly increases the metal surface area available to catalyse the reaction. The palladium is supported on a support of titanium silicate powder.
Research samples of the catalysts are available from BASF Catalysts, a $4bn business which was formed when BASF merged its activities with Engelhard in June 2006.
