Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1976-02-09
1979-04-17
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
562595, C07C 5914
Patent
active
041502418
ABSTRACT:
Pure racemic acid (dl-tartaric acid) and meso tartaric acid are produced by reaction of an alkali maleate with aqueous hydrogen peroxide in the presence of an alkali tungstate in a process wherein the molar ratio of hydrogen peroxide to maleic acid is greater than 1:1 and the alkali salt of cis-epoxysuccinic acid formed together with the alkali tungstate, in a given case after destroying the excess hydrogen peroxide, are converted to free cis-epoxysuccinic acid and free tungstic acid by leading them over a strongly acidic cation exchanger, whereupon the hydrolysis of the free cis-epoxysuccinic acid to racemic acid and meso-tartaric acid can take place either in the presence of or the absence of the free tungstic acid, whereby the tungstic acid in the case of catalyst free hydrolysis before, and in the case of catalyst containing hydrolysis after this hydrolysis is removed with an anion exchanger and the racemic acid is then in known manner crystallized out of the tungstic acid free hydrolysis mixture by lowering the temperature in a given case with evaporation of water, whereupon the meso-tartaric acid remains in the mother liquor, and there is recovered from the mother liquor either by crystallization or by evaporation to dryness, in a given case in admixture with racemic acid, unreacted cis-epoxysuccinic acid and maleic acid, while the anion exchanger laden with the tungstic acid is regenerated in known manner with dilute aqueous alkali and, in a given case, the resulting solution of alkali tungstate, eventually after treatment with activated carbon is returned directly into the epoxidation step.
There is also disclosed a process for the separation of maleic acid from synthetic tartaric acid containing maleic acid in which an aqueous solution of the crude tartaric acid which can also still contain the catalyst used, is led over a basic anion exchanger which is present in the hydroxyl or tartrate form.
REFERENCES:
patent: 2437648 (1948-03-01), Milas
patent: 3875223 (1975-04-01), Yonemitsu et al.
Prescher Gunter
Schreyer Gerd
Deutsche Gold- und Silber-Scheideanstalt vormals Roessler
Killos Paul J.
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