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SiliaMetS®- Metal Scavengers Typical Experimental Procedures

SiliaMetS Metal Scavengers Solution Color

Screening in Batch Reactor Mode (Bulk)

To select the best scavenger for initial screening experiments, do the following steps for each SiliaMetS Metal Scavengers included in the kit. Use 4-8 molar equivalents of each SiliaMetS in respect to the residual metal concentration.

  • 1. Dissolve the crude product to be treated in a suitable solvent (or use directly the crude reaction mixture) and prepare vials containing the same solution volume.
  • 2. Directly, add to these vials the amount needed for each SiliaMetS included in the kit. Note: no pre-wetting of the SiliaMetS is required. See Calculation of the amount of SiliaMetS to use.
  • 3. For initial tests, stir the solution for at least one hour at room temperature.
  • 4. Scavenging progress can be followed by normal analytical techniques. The scavenging progress can be estimated by looking at the color of the solution as demonstrated in the figure. When the scavenging is almost completed, the solution is less colored and SiliaMetS becomes colored. In some occasional cases, if all the samples are still coloured, let them react for a longer time and/or add more equivalents of the SiliaMetS and/or increase the temperature of the reaction.
  • 5. At the end of the scavenging, filter off the SiliaMetS using a fritted funnel or filtration device.
  • 6. Wash the SiliaMetS with additional solvent for total recovery of the API (or compound of interest) and concentrate the solution under vacuum.
  • 7. Analyze the residual metal concentration of each vial to identify the most efficient SiliaMetS Metal Scavenger. Note: you can choose more than one scavenger.
  • 8. If you are satisfied with the scavenging efficiency of the best SiliaMetS, direct scale-up is possible. Otherwise, scavenging optimization can be done with SiliaMetS identified in #7 (see next section).

Screening with SiliaMetS Fixed Bed Mode (SPE or Flash Cartridges)

SiliaMetS fixed bed formats are a great alternative for metal removal and are directly scalable. Initial screening investigations can be done using SiliaPrep 2g/6mL SPE cartridges.

  • 1. Condition the cartridge with 3-4 cartridge volume using the same solvent as the solution to be treated.
  • 2. Add to the top of the cartridge the solution containing the API and the metal and let it pass through the cartridge under gravity
    Note: if needed, a slight positive pressure on the top of the cartridge or a light vacuum can be applied to speed up the flow rate.
  • 3. As shown by the picture on the right, a dark coloured band will be observed on the top of the silica bed most of the time.
  • 4. If the residual solution is still coloured, multiple passes through the same cartridge can be done.
  • 5. Once the scavenging is completed, wash the cartridge using at least 3 column volumes of solvent to insure total API (or compound of interest) recovery. Note: in some particular cases, additional washing may be required.
SiliaMetS Metal Scavengers Thiol

Experiment Optimization with SiliaMetS

If, upon completion of the screening procedure, the scavenging is not completed or you wish to reduce the number of equivalents, or the reaction time, optimization can be undertaken.
Various parameters can be changed one at a time or simultaneously to improve the metal removal efficiency.

Note: you can mix multiple Silia MetS to get superior efficiency.

 

Number of SiliaMetS Equivalents

Residual concentration of Pd(OAC)2 with SiliaMetS Thiol in DMF

For initial screening experiments we suggest to use 4-8 molar equivalents in respect to the residual metal concentration of each SiliaMetS. Once the preferred scavenger is identified, further optimization can be done to reduce the number of equivalents used (typically down to 2-4 equivalents).
Graph represents residual concentration (%) of Pd(AcO)2 with SiliaMetS Thiol in DMR.

 

Subsequent Treatments with SiliaMetS

In some particular cases (equilibrium process or the presence of multiple species), multiple treatments with SiliaMetS could be suitable instead of one single treatment with a larger amount. For optimal results, filtration between each treatment can allow for a higher scavenging efficiency.

 

Reaction time

In some particular cases, where increasing the temperature is impossible, longer contact time with the scavenger can allow higher scavenging efficiency.

Conditions: Pd(AcO)2, THF, SiliaMetS Thiol, RT.

SiliaMetS Metal Scavengers Thiol

Temperature 

In initial screening, we suggest to run the scavenging experiments at room temperature. Usually, metal scavenging is completed after one hour or so. However, if the timescale is too long for your need, higher scavenging rates can be achieved by increasing the temperature. SiliaMetS can be safely used at elevated temperature without degradation and can be added either at room temperature or directly to warm solution.

Mixing Rate

SiliaMetS are mechanically stable and offer excellent scavenging efficiency in batch processes agitated with overhead and magnetic stirrers, as well as orbital shaking under low to moderate agitation rate.
If required, mixing rates can be increased to get better scavenging results. With faster stirring, you improve SiliaMetS dispersion in solution.

pH of Aqueous Solution

When the scavenging is done in aqueous solution, it is possible to use SiliaMetS in a pH range of 2 to 12. Furthermore, depending on the nature of the SiliaMetS, pH can modify the nature of functional groups present on the scavengers by charging them. Scavenging can be affected (i.e.: amine groups in acidic conditions).

Solvent

SiliaMetS can safely be used in a wide range of organic and aqueous solvents commonly used in laboratory and in process, such as DMF, DMSO, THF, 2-butanone, alcohols, ethers, chlorinated solvent, etc. As demonstrated in the graphs below, the nature of the solvent does sometimes influence the scavenging efficiency. If scavenging or kinetic are too slow, changing solvent or co-solvent addition should be considered.

SiliaMetS Format (Mode Used)

One advantage of SiliaMetS is their great compatibility with various technologies. They can be used in batch, in fixed bed (SPE or Flash cartridges), in flow chemistry, or in microwave. Scavenging efficiency can be improved by changing the mode used.

 

Case Studies

Leaching & Stability Studies

Metal Scavengers Calculation

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  1. SiliaMetS thiol metal scavenger - Best scavenger: Ag, Hg, Os, Pd & Ru - Good scavenger: Cu, Ir, Pb, Rh & Sn

    SiliaMetS® Thiol metal scavenger

    SiliaMetS Thiol is our most versatile and robust metal scavenger for a variety of metals under a wide range of conditions.
  2. SiliaMetS® DEAM

    SiliaMetS® DEAM

    SiliaMetS DEAM is a versatile scavenger designed to remove trace metal or boronic acids from reaction intermediates or final APIs. 

  3. SiliaMetS Novel Scavenger Kit. Includes the following products: AMPA - DEAM - DOTA - DMT - Guanidine - Thiol

    SiliaMetS® Novel Scavenger Kit (K34530B)

    This metal scavenger kit includes the following products: AMPA - DEAM - DOTA - DMT - Guanidine - Thiol
  4. SiliaMetS® AMPA

    SiliaMetS® AMPA

    SiliaMetS AMPA is an aminomethylphosphonic acid ligand known for its excellent metal-bonding properties. It is particularly efficient to remove Aluminium, Antimony, Nickel, Lanthanides, and also very effective for Cobalt, Iron, Manganese and Zinc scavenging from reaction intermediates or final APIs. 

  5. SiliaMetS Tin Metal Scavenger Kit (K34730B) - Includes the following products: Carbonate - Cysteine - DEAM - DMT - TAAcOH - TAAcONa - Thiourea - Thiol

    SiliaMetS® Tin Metal Scavenger Kit (Carbonate; Cysteine; DEAM; DMT; TAAcOH; TAAcONa; Thiol; Thiourea) (K34730B)

    SiliaMetS® Tin Metal Scavenger Kit: Carbonate; Cysteine; DEAM; DMT; TAAcOH; TAAcONa; Thiol; Thiourea
  6. SiliaMetS Palladium Metal Scavenger Kit - Includes: DMT - Diamine - Thiol - Thiourea - Imidazole - Triamine

    SiliaMetS® Palladium Metal Scavenger Kit (K34630B)

    This kit includes the following products : DMT - Diamine - Thiol - Thiourea - Imidazole - Triamine
  7. SiliaMetS® Thiourea

    SiliaMetS® Thiourea

    SiliaMetS® Thiourea (Si-THU) is a versatile metal scavenger for all forms of palladium and is widely used in the pharmaceutical industry. It works particularly well in organic solvents. It can also be used to scavenge Ag, Pt, Ru, Rh and Hg. Once complexed with a transition metal, it has been reported as being an effective catalyst.

  8. SiliaMetS® Cysteine

    SiliaMetS® Cysteine

    SiliaMetS® Cysteine (Si-Cys) is the silica bound equivalent of the amino acid Cysteine. By attaching the molecule to the backbone via the amino group, the thiol group remains free and accessible for higher metal scavenging efficiency. It is a versatile metal scavenger for a variety of metals including Pd, Sn, Ru, Pt, Cu, Rh, Cd and Sc under a wide range of conditions and the preferred metal scavenger for tin residues.

  9. SiliaMetS Dimercaptotriazine (DMT) metal scavenger

    SiliaMetS® Dimercaptotriazine (DMT)

    SiliaMetS DMT is the silica - bound equivalent of 2,4,6 - trimercaptotriazine (trithiocyanuric acid, TMT). It is a versatile metal scavenger for a variety of metals and the preferred metal scavenger for ruthenium catalysts and hindered Pd complexes (i.e. Pd(dppf)Cl2).
  10. SiliaBond® Amine

    SiliaBond® Amine

    SiliaBond® Amine (Si-NH2) is an effective scavenger of acid chlorides, sulfonyl chlorides, isocyanates and other electrophiles. Si-NH2 has been shown to be effective metal scavenger and catalyst for Knoevenagel reactions. SiliaBond Amine is also used in chromatography as normal phase sorbent.

  11. SiliaBond® Amine nec

    SiliaBond® Amine nec

    SiliaBond® Amine (Si-NH2) is an effective scavenger of acid chlorides, sulfonyl chlorides, isocyanates and other electrophiles. Si-NH2 has been shown to be effective metal scavenger and catalyst for Knoevenagel reactions. SiliaBond Amine is also used in chromatography as normal phase sorbent.

  12. SiliaMetS® Diamine

    SiliaMetS® Diamine

    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.

  13. SiliaMetS® Triamine

    SiliaMetS® Triamine

    SiliaMetS® Triamine (SiliaMetS WAX-3, Si-TRI) is effective for scavenging metals such as Pb, Co, Ru and Pd. Our screening studies have shown it to be the preferred scavenger for Pb. It can also be used as a scavenger for acid chlorides, isocyanates and other electrophiles.

  14. SiliaMetS® Imidazole

    SiliaMetS® Imidazole

    SiliaMetS® Imidazole (Si-IMI) is a versatile metal scavenger for a variety of metals including Cd, Co, Cu, Fe, Ni, Pd, and Rh under a wide range of conditions and the preferred metal scavenger for iron catalysts.

    SiliaMetS Imidazole can also be used as an amine base in systems that are generally sensitive to basic conditions compared to other SiliaMetS supported bases.

  15. SiliaMetS® TAAcOH

    SiliaMetS® TAAcOH

    SiliaMetS® TAAcOH (SiliaMetS Triaminetetraacetic Acid) is a silica bound metal scavenger for Pd(0), Ni(0) and Cu. It is the supported version of EDTA in its free form. It is an effective scavenger for metals in low or zero oxidation states, which includes many of the most synthetically useful catalysts such as tetrakis-(triphenylphosphine)palladium(0).

  16. SiliaMetS® TAAcONa

    SiliaMetS® TAAcONa

    SiliaMetS® TAAcONa or (or SiliaMetS Triaminetetraacetate, sodium salt) is a silica bound metal scavenger for Pd(II), Ni(II) and Cu. It is the supported version of EDTA in its sodium salt form. It is an effective scavenger for metals in higher oxidation state, 2+ or higher.

  17. SiliaMetS metal scavenger kit (K30730B). Includes the following products: Cysteine, DMT, Imidazole, Triamine, TAAcOH, TAAcONa, Thiol & Thiourea

    SiliaMetS® Metal Scavenger Kit (K30730B)

    This metal scavenger kit includes the following products: Cysteine - DMT - Imidazole - Triamine - TAAcOH - TAAcONa - Thiol - Thiourea
  18. SiliaSep™ Flash Cartridges Amine

    SiliaSep™ Flash Cartridges Amine

    Good alternative for normal phase purification of compounds with basic properties, which would normally have to be purified by reversed-phase.

    SiliaSep flash amine cartridges offer a superior alternative to the other cartridges available on the market.

  19. SiliaSep™ Flash Cartridges Triamine

    SiliaSep™ Flash Cartridges Triamine

    SiliaSep flash triamine cartridges offer a superior alternative to the other cartridges available on the market.

  20. SiliaSep™ Flash Cartridges Diamine

    SiliaSep™ Flash Cartridges Diamine

    SiliaSep flash diamine cartridges offer a superior alternative to the other cartridges available on the market.

  21. SiliaSep™ Flash Cartridges Thiol

    SiliaSep™ Flash Cartridges Thiol

    SiliaSep flash thiol cartridges offer a superior alternative to the other cartridges available on the market.

  22. SiliaSep™ Flash Cartridges TAAcOH

    SiliaSep™ Flash Cartridges TAAcOH

    SiliaSep flash TAAcOH cartridges offer a superior alternative to the other cartridges available on the market.

  23. SiliaSep™ Flash Cartridges TAAcONa

    SiliaSep™ Flash Cartridges TAAcONa

    SiliaSep flash TAAcONa cartridges offer a superior alternative to the other cartridges available on the market.

  24. SiliaSep™ Flash Cartridges Thiourea

    SiliaSep™ Flash Cartridges Thiourea

    SiliaSep flash thiourea cartridges offer a superior alternative to the other cartridges available on the market.

  25. SiliaSep™ Flash Cartridges Dimercaptotriazine (DMT)

    SiliaSep™ Flash Cartridges Dimercaptotriazine (DMT)

    SiliaSep flash DMT cartridges offer a superior alternative to the other cartridges available on the market.

  26. SiliaSep™ Flash Cartridges Cysteine

    SiliaSep™ Flash Cartridges Cysteine

    SiliaSep flash cysteine cartridges offer a superior alternative to the other cartridges available on the market .

  27. SiliaSep™ Flash Cartridges - Open Top (OT) Amine

    SiliaSep™ Flash Cartridges - Open Top (OT) Amine

    SiliaSep OT flash cartridges are compatible with FlashMaster instrument.

    Good alternative for normal phase purification of compounds with basic properties, which would normally have to be purified by reversed-phase.

  28. SiliaSep™ Flash Cartridges - Open Top (OT) Thiol

    SiliaSep™ Flash Cartridges - Open Top (OT) Thiol

    SiliaSep OT flash cartridges are compatible with FlashMaster instrument.

  29. SiliaSep™ Flash Cartridges - Biotage™ Compatible (BT) Amine

    SiliaSep™ Flash Cartridges - Biotage™ Compatible (BT) Amine

    SiliaSep BT flash cartridges are compatible with Biotage i-style compression modules.

    Good alternative for normal phase purification of compounds with basic properties, which would normally have to be purified by reversed-phase.

  30. SiliaPrep™ SPE Cartridges Amine (WAX)

    SiliaPrep™ SPE Cartridges Amine (WAX)

    SiliaPrep Amine is a weak anion exchanger sorbent used in replacement of SAX for strong anions to avoid irreversible retention. Can also be employed as a metal scavenger and in normal phase conditions.

  31. SiliaPrep™ SPE Cartridges Amine nec (WAX)

    SiliaPrep™ SPE Cartridges Amine nec (WAX)

    SiliaPrep Amine nec is a weak anion exchanger sorbent used in replacement of SAX for strong anions to avoid irreversible retention. Can also be employed as a metal scavenger and norman phase conditions.

  32. SiliaPrep™ SPE Cartridges Diamine

    SiliaPrep™ SPE Cartridges Diamine

    SiliaPrep Diamine can be used in replacement of SAX for strong anions. It can also be employed as metal scavenger and in normal phase conditions.

  33. SiliaPrep™ SPE Cartridges Diamine nec

    SiliaPrep™ SPE Cartridges Diamine nec

    SiliaPrep diamine can be used in replacement of SAX for strong anions to be irreversible retention. Can also be employed as metal scavenger and in normal-phase conditions.

  34. SiliaPrep™ SPE Cartridges Triamine

    SiliaPrep™ SPE Cartridges Triamine

    SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.

  35. SiliaPrep™ SPE Cartridges Thiol

    SiliaPrep™ SPE Cartridges Thiol

    SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.

  36. SiliaPrep™ SPE Cartridges Thiourea

    SiliaPrep™ SPE Cartridges Thiourea

    SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.

  37. SiliaPrep™ SPE Cartridges TAAcOH

    SiliaPrep™ SPE Cartridges TAAcOH

    SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.

  38. SiliaPrep™ SPE Cartridges TAAcONa

    SiliaPrep™ SPE Cartridges TAAcONa

    SiliaPrep Metal Scavengers will lower the residual metal concentration of variois metal complexes to single digit ppm.

  39. SiliaPrep™ SPE Cartridges Dimercaptotriazine (DMT)

    SiliaPrep™ SPE Cartridges Dimercaptotriazine (DMT)

    SiliaPrep Metal Scavengers will lower the residual metal concentration of various metal complexes to single digit ppm.

  40. SiliaPrep™ 96 Well Plates Amine

    SiliaPrep™ 96 Well Plates Amine


    Standard SiliaPrep 96 Well Plates are available in 2 mL with different bed weight up to 200 mg. Various sorbents are available and are divided into several sections based on sorbent characteristics.
  41. SiliaPrep™ 96 Well Plates Amine nec

    SiliaPrep™ 96 Well Plates Amine nec


    Standard SiliaPrep 96 Well Plates are available in 2 mL with different bed weight up to 200 mg. Various sorbents are available and are divided into several sections based on sorbent characteristics.
  42. SiliaMetS DOTA

    SiliaMetS DOTA

    SiliaMetS DOTA is a silica-supported tetracarboxylic acid and its various conjugate bases. DOTA molecule is a well-adopted complexing agent. Linked to various metals, so formed-complexes are used as contrast agents in cancer treatments or other medical applications.

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