Silica Bound Scavengers & Reagents
Why work harder when you can work smarter with SiliCycle’s UltraPure Silica Bound Scavengers and Reagents. We offer a wide range of products from metal and organic scavengers to reagents.
The use of solid supported reagents and scavengers is an excellent way to expedite organic synthesis by simplifying the purification process. Standard purification procedures including chromatography, liquid- liquid extraction and crystallization can be time consuming and difficult to scale up.
In many cases supported reagents have distinct advantages over their solution phase counter-parts, the biggest one being the ability to use incompatible reagents, such as an acid and base, simultaneously since they can not react with each other only with the solution phase components of the reaction mixture. Other advantages include the ability to due multiple transformations in a single pot, the immobilization of toxic regents and increased selectivity.
Why tolerate the restrictions of polymer bound scavengers when SiliCycle’s talented cross-functional R&D group has developed techniques which allows us to graft, reactive functional groups onto silica and then end-cap the residual silanol groups for an inert non swelling support, that out performs polymer.
Advantages of Functionalized Silica
Fast Kinetics: Since the silica is surface functionalized
your rate of reaction isn't controlled by the diffusion into and out of the
polymer. Most of our scavengers work in under an hour
Solvent Independent: Silica neither shrinks nor swells in any solvent and
because it's end-capped it won't dissolve in any solvent. Your scavenger doesn't
have to dictate the solvent of your reaction.
Easy to Use: Easy to weigh and handle since silica does not
carry a static charge and is always free flowing. High density makes it suitable
for small volume work. Does not require extensive washing for high recoveries
and won't stick to glassware. Amenable to automation.
Mechanically Stable: Works well with overhead stirring and
can be used with a bottom coupled spin bar for up to four hours.
Thermally Stable:Silica can withstand temperatures over 200 °C and is
suitable for use in microwave synthesizers
Scalable: Works on the microgram to the multi ton scale.
Flexible Formats: Because it doesn't swell silica gel can be packed into variety
of flow through formats such as HPLC columns, Flash cartridges, SPE cartridges
and 96 well plates
Controlled loading: Consistent, accurate loading lot to lot
Unlike polymer, silica is much easier to use. It is easy to weigh and handle
with no static issues and is easily amenable to automation. It is mechanically
stable and works in any format and is easily scaled. It requires little or
no washing because it doesn't swell.
Scavengers
SiliCycle offers a wide range of scavengers to simplify you purification. Scavengers are functionalized silica designed to react and bind excess reagents and/or by products. The process for using scavengers is outlined in figure 1.
In the case of batch processing the scavenger is added to the reaction mixture after completion. The process relies on chemically driven reactions where the excess reagents and reaction byproducts react with and bind to the scavenger. The solution which now only contains product is separated from the resin bound impurities by filtration.
For flow through processing the scavenger is packed into a column (SPE, HPLC, etc) and the reaction mixture is passed through or recirculated through the column until scavenging is complete. Recirculating solution through the packed column is normally only applicable on large scale, pilot plant or higher.
Microwave Assisted Scavenging
This rapidly growing field is highly compatible with silica bound scavengers and reagents. Below(table1) are the results using Si – Amine(figure 1) to scavenge a variety of nucleophiles. The scavenging was carried out using 4 equiv under mircowave conditions: 4 min, 150°C, 300W. No leaching of the reactive groups was obeserved by GC-MS. The integrity of the functionalized silica gel under microwave conditions (700W, 30 min) is not affected.
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