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.

back to top

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.

back to top

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

back to top




  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.

back to top

Related Links