An interesting question for synthesis chemists as the need for reversed-phase flash chromatography for both intermediates and final compounds increases. Historically, normal-phase flash chromatography has been the “go-to” purification tool for synthetic intermediates. Today, however, intermediates and final products are increasingly polar. These polar reaction mixtures cause purification challenges in both separation and recovery with normal-phase (silica) thus requiring use of reversed-phase flash chromatography.
Over the course of my career, I have had terrific interactions with a multitude of chemists discussing chromatography. When it comes to flash chromatography the approaches from these chemists ranged from running generic 0-100% ethyl acetate in hexane gradients to modeled gradients based on tribal knowledge for a type of synthetic molecule to always using TLC for method development to prep HPLC. Each of these techniques are used because they provide some level of success. To me, though, if I spend time and resources synthesizing a highly valuable and unique molecule, then I want to purify the reaction mixture with the best possible method.
The term “Green Chemistry” has become a major part of the science community’s lexicon. When I think about green chemistry and its relationship to flash column chromatography I think of two specific areas where it applies...
Applying green chemistry principals to flash purification is becoming increasingly important. In this post, I discuss ways to make flash column chromatography greener by reducing solvent use through optimization of gradient shape.
This is a follow-on to my earlier post where I presented some greener alternatives to DCM as a solvent in flash column chromatography.