Reaction Kinetics for An API Process with Multiple Pathways and Hidden Intermediates

Variable results from a reaction often points to interactions between multiple steps in the reaction mechanism. This is complicated by reaction intermediates that are difficult to detect by HPLC or spectroscopy. An example of a step in an API process is discussed that illustrates these points. It was found that small changes in a reagent resulted in large changes in selectivity due to the presence of multiple reaction pathways controlled by an equilibrium reaction.