Solid Supported Metal-Scavenging Agents
Web Published:
11/14/2013
Compositions and methods for sequestration and removal of transition metal complexes (e.g. catalysts) from solution.
Despite the wide use of transition metal catalysts in chemical processes across a variety of industries, their removal and recovery from post-reaction mixtures remains a major challenge. Traditional removal methods such as chromatography, activated carbon, extraction, distillation and recrystallization are less than ideal, either because they do not effectively remove metal impurities or require significant time and effort, both of which can be particularly costly during large scale synthetic procedures. While metal-scavenging reagents have been developed to address these issues, existing scavengers are generally unable to bind strongly to multiple metals, let alone multiple oxidation states of a metal; therefore, no single scavenger can efficiently remove all of the different metal species, a reality that continues to drive the development of new metal scavengers.
This invention provides an isocyanide-based solid supported system for sequestering and removing metal-based catalysts from solution. Preliminary studies in which the system was used to remove ruthenium from metathesis reactions demonstrated its ability to achieve near complete (up to 99.99%) removal of residual ruthenium under a variety of reaction conditions. When used in applications employing second-generation Grubbs metathesis catalysts, not only was the scavenger able to effectively remove ruthenium, but it completely quenched metathesis activity. Beyond ruthenium, the system has also proven to be highly effective for the removal of other transition metals involved in other reactions, including but not limited to palladium, both Pd(0) and Pd (II), in several different cross-coupling reactions (e.g. Suzuki), as well as in Buchwald–Hartwig amination reactions. These agents may be used with a variety of solid supports as a standalone system, requiring filtration, or in combination with column chromatography to further lower the levels of residual metals.
The scavenging agents provided here are able to achieve near complete removal of a variety of metals, including various oxidation states of certain metals, in much shorter time compared to commercially available scavengers, and have shown the ability to completely quench metathesis reactions involving second generation Grubbs catalysts.
Removal and recovery of metals from chemical reactions
US Non-Provisional Patent Application filed September 30, 2014 20160243463 EP & JP applications also pending.
Prototype demonstration.
Available for licensing or collaboration.
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