Esterification synthesis of ethyl oleate catalyzed by Brønsted acid–surfactant-combined ionic liquid

Figures & data

Figure 1. Illustration of auto-isolation of water generated during esterification.

Figure 2. TGA curves for [SB3-12][HSO₄].

Figure 3. Factors on oleic acid conversion (based on the mass of oleic acid): (a) catalyst loading, reaction conditions: n (ethanol): n (oleic acid) = 1.5:1, 78°C, 3 h; (b) reaction time, reaction condition: n (ethanol): n (oleic acid) = 1.5:1, 5 wt% catalyst (based on mass of oleic acid), 78°C; (c) amount of ethanol, reaction condition: 5 wt% catalyst (based on mass of oleic acid), 3 h, 78°C; (d) water content on the catalytic activity, reaction condition: n (ethanol): n (oleic acid) = 1.5:1, 5 wt% catalyst (based on mass of oleic acid), 3 h, 78°C.

Figure 4. UV spectra of MO in the reaction system with different reaction times ((a) 1 h λ_max = 402 nm; (b) 2 h, λ_max = 412 nm; (c) 3 h, λ_max = 420 nm) at 298 K, [MO] = 1 × 10⁻⁵ M.

Figure 5. DLS study of the reaction system showing formation of micelles.

Figure 6. TEM images of the oleic acid/[SB3-12][HSO₄]/ethanol system.

Figure 7. Reusability of [SB3-12][HSO₄] for esterification. Reaction conditions: n (ethanol): n (oleic acid) = 1.5:1; catalyst = 5wt% (based on the mass of oleic acid), 3 h, 78°C.

Figure 8. Different stages of esterification catalyzed by [SB12-3][HSO₄].