Oxalic Acid → Malic Acid

Participants

Reaction Conditions

Reaction Steps

A maleic acid solution was prepared by dissolving 56.0 g (0.571 mol) of maleic anhydride in 124.3 ml of water. 116.2 g of this solution was added to 71.3 g of a 48% lye solution (0.856 mol NaOH). During the addition the temperature of the reaction mixture was maintained at 70-90° C. Lanthanum(III)oxide, La2O3,(15.5 g, 0,048 mol) was dissolved in remaining maleic acid solution ( 64.1 g, 0.192 mol) and added to the reaction mixture together with diethanolamine (20.0 g, 0.190 mol). The reaction mixture was stirred at 95° C. under a reflux condenser for 24 hours. The reaction mixture was rendered acidic (pH 3.5) by addition of oxalic acid, C2O4H2.2H2O (47.96 g in 71.90 ml of water, 0.380 mol) and stirred at 80° C. for 1 hour. The reaction mixture was cooled and the formed La(III) oxalate precipitate was removed by filtration. From the remaining solution (194.1 g), which contained water 75.2%, the organic compounds were analyzed by means of 13C NMR spectra. BCEEAA and BCEEA were identified from the 13C NMR spectra. Unreacted initial substances were identified on the basis of reference spectra: diethanolamine and maleic acid, as well as oxalic acid used for the precipitation of the catalyst. Malic acid and fumaric acid were formed as byproducts of the reaction; these were also identified on the basis of reference spectra.

Provenance & Evidence