ABSTRACT
Jaime B. Woods1, Robin Spears1, Jürgen Krauter2, Tim McCarthy3, Micheal Murphy3, Lee Hord4, Peter Doorley4, Baoshu Chen1
1 Degussa Corporation, Business Line Catalysts, 5150 Gilbertsville Highway,
Calvert City, KY 42029, USA 2 Degussa AG, Business Line Catalysts, Rodenbacher Chaussee 4, D-63457,
Hanau, Germany 3 Degussa Corporation, Business Line Catalysts, 379 Interpace Parkway,
Parsippany, NJ, 07054, USA 4 Mobile Process Technology, 2070 Airways Boulevard, Memphis,
TN 38114, USA
jaime.woods@degussa.com Abstract Catalysis is a valuable and indispensable tool in organic synthesis. Transition metals, most preferably precious metals, are often used. However, potential residual metal contamination from these heterogeneously or homogeneously catalyzed reactions may be detrimental to product quality or, as in the case of active pharmaceutical ingredients (API’s), the metal concentration in the final product may be regulated. Degussa’s Deloxan® Metal Scavengers recover valuable precious metals from reaction mixtures and reduce the metal concentration in process solutions to an acceptable level (<5 ppm). In this study, two Deloxan® Metal Scavengers were investigated. The first, THP II, is a thiourea functionalized polysiloxane while the second, MP, is mercapto functionalized. Both resins have been tested in solutions containing 20 – 100 ppm Pd(II), Pd(0) or Ru(II). In addition to different metals and oxidation states, the effects of solvent (polar vs. nonpolar), temperature (25 – 80 °C) and mode (fixed bed vs. batch) were explored. These resins were found to reduce precious metal concentrations in process solutions to levels at or below the target concentration of 5 ppm, even at room temperature in the case of Pd(II) and Pd(0). The results of this study will be discussed. Introduction Transition metal catalyzed reactions are becoming commonplace in synthetic chemistry. Heterogeneous or homogeneous catalysts containing valuable metals such as palladium, platinum, rhodium and ruthenium are frequently used in the manufacture of active pharmaceutical ingredients (API).[1] The use of such catalysts can lead to metal contamination of the product. The amount of precious
metal residue permitted to remain in pharmaceutical products is strictly regulated and for Pd and other platinoid metals this level should be below 5 ppm.[2]
Several methods of metal removal from process solutions exist. Some of these approaches include crystallization, distillation and extraction. However, these methods can be very time-consuming and often result in loss of some valuable product. To overcome these shortcomings, Degussa has developed Deloxan® Metal Scavengers as an attractive option to solve problems associated with transition metal contamination of process solutions.[3, 4, 5] Two resins are commercially available. Deloxan® THP II (1) is a thiourea functionalized, macroporous, organofunctional polysiloxane while Deloxan® MP (2) is mercapto functionalized.
