Mucic acid

Mucic acid, C6H10O8 or HOOC-(CHOH)4-COOH, is obtained by the oxidation of lactose, 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. 