Production of lactic acid esters catalyzed by heteropoly acid supported over ion-exchange resins

The heterogeneous liquid-phase esterification reaction of lactic acid with ethyl alcohol accompanied with lactoyllactic acid hydrolysis over heteropoly acid supported on ion exchange resin catalysts was investigated at 343 K with ethanol to lactic acid molar ratio of 1:1. The catalysts with 5-20% of tungstophosphoric (H(3)PW(12)O(40).xH(2)O) and molybdophosphoric (H(3)PMo(12)O(40).xH(2)O) acid type of heteropoly acids over Lewatit(R) S100 showed higher activities than the resin itself. DRIFTS and XRD analysis indicated the formation of amorphous heteropoly acid layer, which is strongly bonded to the resin surface with hydrate structure. Reaction experiments showed molybdophosphoric acid has slightly higher activity than the tungstophosphoric acid, which yields slower deactivation. The reaction model was established by considering the hydrolysis reaction of lactoyllactic acid under the reaction conditions and the esterification step. Reaction rate constants for homogeneous self catalyzed, ion exchange resin catalyzed, and kinetic contribution of heteropoly acid loading were calculated. Kinetic analysis of the reaction data revealed that the active proton sites do not increase proportionally with the amount of heteropoly acids over the resin surface and proton efficiency of the catalysts decreases with increasing loading. It was observed that molybdophosphoric acid loaded S100 catalysts have higher proton efficiency than the tungstophosphoric acid loaded counterpart.


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The esterification of lactic acid with ethanol over Lewatit S 100, strong cation ion exchange resin catalyst, was studied in counter current vapor-liquid contactor type differential reactor by feeding ethanol and lactic acid solution as vapor and liquid phases, respectively. The ethanol vapor phase was diluted by dry air and the water removal was achieved by the mass transfer of water from liquid to vapor phase. Effect of ethanol to lactic acid feed molar ratio and vapor flow rate on fractional conversion a...
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L-Aspartic acid (L-Asp) was produced using Escherichia coli (ATCC 11303), and its recovery from the reaction mixture was studied using reverse micelle and gas hydrate methods. The effect of initial substrate concentration on L-Asp production was also investigated, and inhibition was shown to occur above 0.75 mol L-1. The values of the kinetic constants were determined as r(max) = 2.33 x 10(-4) mol L-1 min(-1), K-M = 0.19 mol L-1, and K-ss = 3.98 mol L-1. The reverse micelle phase used for extraction contain...
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Kayalar, Metin; Demir, Ayhan Sıtkı; Department of Chemistry (2005)
A convenient and new method for the synthesis of 1,2,3,5-tetrasubstituted pyrrole derivatives starting from 1,3,-dicarbonyl compounds through acid catalyzed cyclization reaction is described. Alkylation of 1,3-dicarbonyl compound with propargyl bromide followed by one step cyclization with the introduction of primary amines in the presence of catalytic amount of triflouroacetic acid (TFA) affords the corresponding pyrrole derivatives in high yields. The investigations on the studies of developing a new meth...
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Oligo-2-aminophenol (OAF) was synthesized with oxidative polycondensation of 2-aminophenol and hydrogen peroxide in an aqueous alkaline medium at 80 degrees C. Oligo-2-aminophenol with thiophene side groups (TOAF) was obtained by the reaction of OAF and thiophene-3-acetic acid. Graft copolymers of TOAF and pyrrole were synthesized by electrochemical polymerization in p-toluene sulfonic acid (PTSA)/water medium. Characterization of the graft copolymer (TOAF-g-Py), was carried out by combination of techniques...
Citation Formats
E. AYTURK, H. Hamamcı, and G. Karakaş, “Production of lactic acid esters catalyzed by heteropoly acid supported over ion-exchange resins,” GREEN CHEMISTRY, pp. 460–466, 2003, Accessed: 00, 2020. [Online]. Available: