2. Parameters Effect On Scavenging Efficiency
A metal scavenging study using SiliaBond® Metal Scavengers products was conducted on various metal catalysts commonly used in organic synthesis. Various parameters were studied for their influence on the scavengers' robustness as well as to establish the best conditions to bring the level of metal down to an acceptable level for the pharmaceutical industry (i.e.: solvent, number of equivalents, temperature, reaction time, and nature of the catalyst).
Solvent effect on Scavenging Efficiency
SiliaBond Metal Scavengers can safely be used in any organic and aqueous solvents. However, the nature of the solvent does sometimes influence the scavenging efficiency.
Reaction Time and Number of Equivalents effect on Scavenging Efficiency
The fast scavenging kinetic of SiliaBond Metal Scavengers allows the reduction of the residual metal concentration to very low ppm in a few minutes. However, various parameters affect the kinetic. The influence of reaction time, temperature, and number of equivalents used are parameters to consider.
SiliaMetS® DMT (Si-DMT) is the silica bound equivalent of 2,4,6-trimercaptotriazine (trithiocyanuric acid). It is a versatile metal scavenger for a variety of metals including Cd, Co, Ni, Pd, Pt, Rh, and Ru under a wide range of conditions and the preferred metal scavenger for ruthenium catalysts.
TMT has been reported to efficiently remove palladium and heavy metals by precipitation. Unfortunately, its solubility in organic solvents causes problem. SiliaMetS DMT solves this issue and almost all solvents can now be used.
SiliaMetS® Diamine (Si-DIA) is a proven scavenger for metals and electrophiles. It scavenges acids, acid chlorides, anhydrides, aldehydes, isocyanates, and chloroformates as well as Pb, Ni, and Cd.