Green chemistry in APIs manufacturing:
A forthcoming revolution now mature
Faced by increasing manufacturing cost and by numerous quality problems, the fine chemicals and pharmaceutical industries are slowly, but inevitably, shifting to green chemistry synthetic methods: Biocatalysis and homogeneous catalysis first; and then to heterogeneous catalysis, well beyond typical hydrogenation reactions over Pt/C or Pd/C conventional catalysts. We have explained in detail elsewhere how, dwarfed by the typical E-factor = 0.1 value of the petrochemicals industry, the E-factor (kilogram of waste per kilogram of API manufactured) approaching 200 typical of homogeneously catalyzed API synthetic processes has marked for the last decade the industry’s process obsolescence (1).
Yet this situation is now changing thanks to the concomitant introduction of new heterogeneous catalysts coupled to manufacturing under flow conditions. Second-generation commercial heterogeneous catalysts suitable for carbon-carbon coupling, debenzylation, hydrosilylation and many other industrially relevant reactions, including conversion of natural terpenes into fragrances, perfumes, flavours, pharmaceuticals and synthetic intermediates, are now commercially available.