Don't forget non-contaminating impurities

15 November 2004

Minimising impurities in APIs and chemical intermediates usually has a double benefit — improved product quality and yield. But don’t forget about impurities, which are removed during purification steps such as crystallisation. Even though these impurities may not have any impact on product purity, as they are removed during the purification step, they can have a big impact on yield. A recent OPRD paper describes improvements to the synthesis of Cefmatilen so that initially the impurity profile of the final product was improved by modifying reaction conditions to minimise impurities which were present in the API, but then went on to consider impurities which appeared in the crystallisation mother liquors and so improve overall yield.

T. Kobayashi et al., Org. Process Res. Dev., 2004, 8(5), 744.