After my seminars, I often receive questions from astute attendees on the topic of activated carbon, and how the more modern powerful approach of metal scavenging compares to the traditional application of activated carbon. This can be an emotive topic, sometimes the question can be a blunt as ‘What’s wrong with carbon? It’s the way most process groups have historically removed transition metals such as palladium.'
Once a chemist has seen and understands potential for the application of metal scavenging and reduction of classical iterative metal migration steps, the next question we receive usually relates to how best to apply them to a reaction.
I recently read an interesting paper from Graham Wynne and his many collaborators at the University of Oxford and CEMAS describing just how much residual palladium (Pd) is making its way through the standard purification processes employed by medicinal chemists.
Whether for pharma, fine chemical, agrochemical, electronic or natural product research, in recent years, there has been increasing pressure to achieve and deliver higher purity products. Chemical products derived from various synthetic chemistry approaches carry with them an inherent risk of by-products and therefore contamination can be a big problem. Potential contaminants are numerous and can be solvent, reagent or catalyst derived...
Removing palladium has become more and more difficult for a number of reasons. Industry is using it more frequently, due to its greener credentials as a catalyst but regulatory bodies are also reducing acceptable limits in APIs. One of the most significant changes for pharma recently has been increased scrutiny of impurities in pharma products.
There are two starting points, depending on your preference of whether you want to stir in a batch or flow something though a tube. If you plan to use large scale up reactors, then batch stir methods are great, but if you imagine wanting to flow material through a ‘cleaning’ column, then the SPE quick test works well.
Now we have a screening candidate, we just need to scale up our work, it is always advisable to initially to scale in factors of ~10 in our experience, although for well-used processes and repetitive batch processing, it is possible to screen grams and go straight to Kgs.