Transition metal catalysts are powerful reagents that comply with principles of green chemistry. They are used sparingly, confer atom and economic efficiency, but may themselves be difficult to remove after the reactions. Metal scavengers are a class of materials that have been designed to specifically remove the metals, leaving the rest of the system untouched.
Traditional methods for removing metals include adsorption on carbon, distillation, precipitation or recrystallization. These techniques may be indiscriminate, energy intensive, non-reproducible or may actually increase the concentration of metal within an API crystal structure.
Biotage metal scavengers are effective for the removal of a variety of metals (such as PGM’s) from catalyzed reactions or final products such as APIs.
This technology can be applied to a variety of different industries – from pharmaceutical to fine chemical, from flavors and fragrances to agrochemical, from water treatment to industrial waste management. The mode of operation is very simple with wide solvent compatibility and specific reactivity, and metal scavengers impose very little constraint or stress on typical workflows.
Biotage metal scavengers are designed to be added, stirred and filtered, leaving pure products in the solution. This step-wise approach significantly reduces the traditional metal removal processing burden.
A variety of different metals may be removed, depending on the scavenger chosen. The following chart is a guide to metal scavenger selection. For more information please download the metal scavenging guide or contact your local Biotage representative.
Utilization of synthetic chemistry routes developed in late lead optimization is becoming more widespread as the desire to efficiently confirm pre-clinical compounds has increased. In some cases, chemical processes use reagents which are specific and cannot be substituted on scale up. Such reagents include transition metal catalysts.
Biotage® Metal Scavenging Screening Toolkits are essential tools that enable quick and efficient identification of candidate metal scavengers for an application. Containing our most popular metal scavengers, with protocols for screening and scale up, whether working with batch stirring workflows or flow through cartridge options in fixed bed formats, these all in one kits are the best starting place for the optimum result.
Biotage® MP-TMT is a macroporous polystyrene-bound trimercaptotriazine, a resin bound equivalent of 2,4,6-trimercaptotriazine (TMT). MP-TMT scavengers residual palladium from palladium catalyzed reactions and has also shown to remove other metals. The MP-base copolymer has been designed to yield a robust, low swelling material, which makes it ideal for restricted volume environments. Its unique pore structure provides greater access to the reactive sites resulting in faster reactions and higher recoveries.
ISOLUTE® Si-TMT is the silica bound equivalent of 2,4,6-trimercaptotriazine (TMT). Si-TMT has been shown to efficiently scavenge residual palladium from palladium-catalyzed reactions.
ISOLUTE® Si-Thiol is the silica-bond equivalent of 1-propanethiol, which is useful for covalent scavenging of electrophiles. The main application is the use to scavenge a variety of metals used in organic chemistry including Pd, Pt, Cu, Hg, Ag and Pb.
ISOLUTE® SCX-2 belongs to a class of strong supported acids. As a bound sulfonic acid, it has a natural propensity to bind alkali and some transition metal group metals, which means that it can be used as a scavenger for metals with a +I or +II oxidation state, such as Na, K, Li, also Pd, Rh, and Ru. Since SCX-2 is acidic in nature, it is typically used as a metal scavenger when the target product is not basic, to avoid the obvious acid/base product binding interactions with the scavenger.
ISOLUTE® Si-Trisamine is a silica bound propyl-tris(2-aminoethyl)-amine. Si-Trisamine is a very powerful scavenger of electrophiles from aqueous or organic solutions as well as an effective scavenger for transition metals (+II oxidation states).