Organic Synthesis

 
Vol. 2, No. 6
Functionalized SILICA GELS for Organic Synthesis

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Introduction / Quality Control / Organic Synthesis / Scavengers
Supported Reagents / Linker Resins / References

UltraPure Modified Silica Organic Synthesis

Properties of Silica Gels
  • Very high surface area (~ 500 m2/g);
  • High silanol density;
  • Very high thermal resistance;
  • Good mechanical stability;
  • No swelling in organic solvents;
  • No restriction on solvent choice.
New generation of Silica-based Scavengers
  • High yields
  • Prepared from high-purity silica gel
  • Demonstrate broad solvent compatibility
  • Do not swell
  • Easy to handle
  • Time saving

Silica-based scavengers have been developed for use with a variety of solvents, thereby countering the problem posed by swelling.

SiliCycle's acid-washed UltraPure Silica Gel assures a pH-controlled medium with very low levels of metal contaminants, thus preventing undesirable reactions. The narrow range of particle sizes of our silica gel (40-63 µm) is especially important in flow-through systems, as it results in increased uniformity (no channeling and greater reproducibility) and fewer "fine-end" particles (lower back pressure, no clogging of frittered filters and no fine materials to contaminate the product).

As silica-based products do not swell, they have a higher scavenging capacity for a given volume. Simply add two to four equivalents of the appropriate scavenger in relation to the reagent or side product you want to scavenge and in most cases, an hour at room temperature is all it takes!

Silica-based scavengers are easy to handle as they do not develop any static charge when, plates, cartridges and columns are filled.

Scavengers normally react covalently with the contaminants they remove from the solution and are usually discarded.

All products are rigorously end-capped to present a solute with no highly adsorptive or reactive surface.

Listed below are some examples of scavenging results:

Catalog No. Scavenger Compound scavenged % scavenged
53,778-0 Isocyano Benzylamine 91
53,794-2 Thiocyano Benzylamine 98
36,425-8 Amino Phenylchloroformate 100
53,791-8 Ethylenediamino Phenylchloroformate 100
53,792-6 Diethylenetriamino Phenylchloroformate 99
53,804-3 Dimethylamino HCl 100
53,808-6 Mercapto Benzaldehyde 81
53,797-7 Sulfonyl chloride Benzylamine 100
53,798-5 Pyridyl HCl 95
53,807-8 Propionyl chloride Benzylamine 100
53,795-0 Imidazol-1-yl HCl 100

 

  1. 2-4 eq. for 1 hour in methylene chloride or hexanes at RT
  2. Amino has been used to scavenge acid chlorides and has proven better than the polymer- supported amines. McComas, W. et al. Tetrahedron Lett. 2000, 41, 3573.