Variation of the catalyst solubilities during the esterification of oleic
acid with methanol was also investigated. All catalysts were soluble in
the reactionmixture at 65 °C, and thus, all of themhomogeneously catalyzed
the reaction. At the end of the reaction, themixturewas cooled to
roomtemperature. Itwas found that [TMAPS]PWand [MIMPS]PWwere
soluble in the reaction mixture at room temperature. It may be due to
their relatively high solubilities in methanol (Table 2, entries 1 and 2).