octahedral crystal(s); formed by dissolving Ga2O3 or Ga(OH)3 in sulfuric acid and precipitating with ether or alcohol [MER06]
Gallium(III) sulfate hydrate is used in the preparation of other gallium compounds such as gallium oxide. It is supported on silica gel act as a solid acid catalyst, which is employed as a heterogeneous catalyst for the esterification of p-hydroxybenzoic acid and heptanol to give n-heptyl p-hydroxybenzoate. On reacting with strong acid cation ion exchange resin, it exhibits excellent catalytic activity, which is used for synthesizing amyl hexanoate.
Recrystallisation from H2O gives the 16-18H2O hydrate (solubility at 20o is 170g/100mL). Alternatively dissolve it in 50% H2SO4 and evaporate (60-70o), cool and precipitate it by adding EtOH/Et2O. On heating at 165o it provides the anhydrous salt, which is a white hygroscopic solid. [Reimmann & Tanner Z Naturforsch 20B 71 1965.]
