Mucic acid

Mucic acid
IUPAC name (2S,3R,4S,5R)-2,3,4,5-tetrahydroxyhexanedioic acid
Other names Galactaric acid
Identifiers
CAS number	526-99-8
PubChem	3037582
Jmol-3D images	Image 1
SMILES C(C(C(C(=O)O)O)O)(C(C(=O)O)O)O
Properties
Molecular formula	C6H10O8
Molar mass	210.1388
Y acid (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Mucic acid, C₆H₁₀O₈ or HOOC-(CHOH)₄-COOH, (also known as galactaric or meso-galactaric acid) is obtained by nitric acid oxidation of galactose or galactose-containing compounds like lactose, dulcite, quercite, and most varieties of gum.

It forms a crystalline powder which melts at 213 °C. It is insoluble in alcohol, and nearly insoluble in cold water. Due to the symmetry in the molecule, it is optically inactive even though it has chiral carbon atoms (i.e., it is a meso compound). 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

Use

Mucic acid can be used to replace tartaric acid in self rising flour or fizzies.

References

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.