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Working
with Silica Supported Scavengers & Reagents
Silica supported scavengers
and reagents are easy to work with and offer many advantages
over conventional polymer bound products.
This document details the general features of functionalized
silica with tips on how to use them effectively. If you
have any questions
or comments, please do not hesitate to contact
us.
Unfunctionalized silica is an inorganic macropolymer made of
[SiO4]4-tetrahedra (Figure 1) with polar silanol groups on
the surface, which give silica the polar properties that make
it useful for flash chromatography.
In functionalizing the silica we take extra steps to eliminate these properties
to provide a completely inert support. After grafting the desired functional
group onto the silica we end cap the remaining silanol groups (Figure 2). This
eliminates the polar properties of the silica making it suitable to use in any
solvent.
| Figure 1: |
| Functionalized end-capped Silica |
Advantages
of Silica Bound Products
- Fast Kinetics:
Since
the Silica is surface functionalized it reacts much faster
than conventional polymer bound reagents where the reaction
is slowed
by the
rate of diffusion through the polymer and can be slowed further by the
polymer ability to swell.
- Works under a wide range of conditions:
The inert silica
works in all solvents, organic and aqueous. It does not
swell or dissolve in any solvent.
It has a
high thermal stability and can be used in microwave applications.
- Easy to
use:
Unlike polymer, silica is much easier to use. It
is easy to weigh and handle with no static issues and is easily
amendable
to
automation.
It
is mechanically stable, works in any format and is easily scaled. It
requires
little or no washing because it does not swell.
Handling Silica
Weighing:
Handle like you would any free flowing
solid. Remember most applications require an excess so “approximate” weighing
works very well.
Agitation:
Shakers and overhead stirrers work best;
magnetic spin bars can be used for up to 4 hours. Silica
will not scratch
glass lined reaction vessels.
We’ve been using the same glass lined reaction vessels for 4 years
to manufacture our products.
Filtering:
Can be filtered under gravity or vacuum, for optimum
product recovery rinse with a small aliquot of solvent. Silica does not stick
to glass like
polymer
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