Nitric Acid → Maleic acid, disodium salt

Temperatur

80 °C

A disodium maleate solution was prepared by dissolving 19.6 g (0.2 mol) of maleic anhydride in 50 ml of water and by adding the resulting maleic acid solution to 33.3 g of a 48% lye solution (0.4 mol NaOH). During the addition the temperature of the reaction mixture was maintained at 70-90° C. Lanthanum(III)oxide, La2O3, (8.15 g, 0.025 mol) was dissolved in 65% nitric acid (16.8 g, 0.173 mol) and in 12 ml of water and added to the reaction mixture together with N-methyl diethanol-amine (11.9 g, 0.1 mol). The reaction mixture was stirred at 85° C. under a reflux condenser for 70 hours. The reaction mixture was cooled and rendered acidic (pH 1-2) by addition of sulfuric acid. The formed La(III)sulfate precipitate was removed by filtration. The remaining sodium sulfate was precipitated by addition of acetone. After filtration and concentration the remaining solution (7.2 g), which contained water 67.6 w-%, the organic compounds were analyzed as silyl or methyl ester derivatives by means of 13C NMR spectra and by GC-MS (table 1, entry 3, and table 2, entry 3, respectively).

1. additionDuring the addition the temperature of the reaction mixture
2. temperatureThe reaction mixture was cooled
3. customThe formed La(III)sulfate precipitate was removed by filtration
4. customThe remaining sodium sulfate was precipitated by addition of acetone
5. filtrationAfter filtration and concentration the remaining solution (7.2 g), which

ORD-Eintrag

ord-40494070c5294564be03e92a75bc5ebc

Quelldatensatz

uspto-grants-2003_07

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06590120B1