Metal Scavengers

Chemfiles Volume 5 Article 11

Metal compounds are widely used in organic and medicinal chemistry as either reactants or catalysts. Since most metal ions have physiological activities, reducing residual metal levels has become a key step in syntheses of bioactive compounds.1 Application of resin scavengers is an efficient method to remove metal ions during postsynthesis purification.2Sigma-Aldrich has developed several different functionalized resin scavengers to remove metals in a variety of organic syntheses.


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Typical Procedure of Removal Metals

Add 3–5 eq. of resin scavenger to an organic solution of crude product containing metal ion. The resulting mixture is stirred for 4–16 h at room temperature to allow the scavenger to fully bind to the metal ions. In some cases, the addition of a few drops of water to the solution is necessary to increase the binding rate. The scavenger is then removed by filtration.

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Maximum Binding Capacity of Scavengers

The maximum binding capacity of the scavenger was determined by stirring a mixture of a scavenger (1 eq.) and a metal salt (2.5–4 eq.) in an organic solvent (THF, MeOH, EtOH, dichloromethane) or a mixture of two solvents overnight. The resin was filtered and washed with solvent, dried, and then analyzed for metal content by microanalysis.


Metal 6-Thionicotinamide, Polymer- Bound (643904) Ethylenediaminetriacetic Acid Acetamide, Polymer-Bound (656844) N,N,N’-Trimethylethylenediamine, Polymer-Bound (656836)
Ag(I) 1.45 mmol/g Not tested Not tested
Cd(II) 1.07 mmol/g 1.28 mmol/g Not tested
Co(II) 1.11 mmol/g 0.89 mmol/g 1.41 mmol/g
Cu(I) Not tested 1.48 mmol/g 1.49 mmol/g
Cu(II) 1.00 mmol/g 1.57 mmol/g 1.10 mmol/g
Hg(II) 0.67 mmol/g Not tested Not tested
Ni(II) 0.35 mmol/g 0.47 mmol/g 1.15 mmol/g
Pd(II) 0.79 mmol/g 0.47 mmol/g 1.41 mmol/g
Zn(II) 1.07 mmol/g 1.48 mmol/g 1.27 mmol/g

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Materials

     

References

  1. Welch, C. J. et al. Org. Process Res. Dev. 2005, 9, 198.
  2. Urawa, Y.; Miyazawa, M.; Ozeki, N.; Ogura, K. Org. Process Res. Dev. 2003, 7, 191.

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