What is a supported reagent?
A supported reagent is a reactive functional group grafted onto insoluble silica. Unlike a scavenger, which is added once a reaction is completed, a supported reagent is added at the beginning of the reaction; it replaces the homogeneous reagent and allows the reagent to be used in greater excess driving the reaction to completion.
It also facilitates multiple step one pot reactions. The spent reagent is easily removed by filtration. Bound reagents are an excellent alternative in cases where the reagent is used in excess and can be difficult to remove such as triphenylphosphines. Purification is now a simple filtration and evaporation process.