Mucic acid

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Mucic acid, C₆H₁₀O₈ or HOOC-(CHOH)₄-COOH, is obtained by the oxidation of milk sugar, dulcite, galactose, quercite and most varieties of gum by nitric acid.

It forms a crystalline powder which melts at 213 °C. It is insoluble in alcohol, and nearly insoluble in cold water. When heated with pyridine to 140 °C, it is converted into allommic acid. When digested with fuming hydrochloric acid for some time it is converted into a furfural dicarboxylic acid while on heating with barium sulfide it is transformed into athiophene carboxylic acid. The ammonium salt yields on dry distillation carbon dioxide, ammonia, pyrrol and other substances. The acid when fused with caustic alkalis yields oxalic acid.

With potassium bisulfate mucic acid forms 3-hydroxy-2-pyrone by dehydration and decarboxylation.

Reaction of mucic acid to 3-hydroxy-2-pyrone with a) potassium bisulfate 160 °C / 4 hrs. b) hydrochloric acid to pH = 7

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• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.