Research Article

Optimization of Process Variables in the Synthesis of Tributyl Citrate Using a Polyvinylpolypyrrolidone-Supported Brønsted Acidic Ionic Liquid Catalyst

Table 2

Esterification of citric acid with n-butanol using different catalysts.

EntryCatalystaConversion (%)bYield (%)c

159.712.5
2H2SO496.491.3
3PTSA96.592.2
4[BsMIM]PTSA96.191.9
5[BsPVPP]HSO496.992.1

aReaction conditions: n-butanol (0.3 mol), citric acid (0.06 mol), [BsPVPP]HSO4 (6 wt%), and 115°C for 5 h. H2SO4, H3PW12O40, and [BsMIM]PTSA were used in a similar proton content as [BsPVPP]HSO4. bCitric acid conversion. cTBC yield.