silica gel Cation exchanger phase, pKa < 1, to extract amines Acid catalyst and basic impurity scavenger for amines, alcohols, and other nucleophiles Less acidic than SCX...: Diatomaceous earth; Diatomite; Fossil flour; Kieselguhr; Siliceous earth Hold up particulate materials such as Pt (IV) oxide and Pd/C catalysts as filtration device for subsequent workup...