5126. Isoascorbic Acid

Nomenclature

CAS number: 89-65-6
d-erythro-Hex-2-enonic acid γ-lactone; d-araboascorbic acid; erythorbic acid; isovitamin C; saccharosonic acid; glucosaccharonic acid; d-erythro-3-ketohexonic acid lactone; d-erythro-3-oxohexonic acid lactone; erycorbin; Mercate “5”; Neo-Cebicure.
C6H8O6; mol wt 176.12.
C 40.92%, H 4.58%, O 54.51%.

Description and references

Epimer of l-ascorbic acid. Has one-twentieth of the vitamin C activity of l-ascorbic acid. Prepd by treating methyl 2-keto-d-gluconate with sodium methoxide: Maurer, Schiedt, Ber. 66, 1054 (1933); 67, 1239 (1934); Ohle et al., ibid. 67, 324 (1934); Baird et al., J. Chem. Soc. 1934, 63; Reichstein et al., Helv. Chim. Acta 17, 516 (1934). Synthesis from sucrose: Heimann, Reiff, Pharm. Zentralhalle 93, 97 (1954). Production by Penicillium spp: Takahashi et al., Nature 188, 411 (1960); US 3052609 (1962 to Sankyo); Bull. Agric. Chem. Soc. Jpn. 24, 533 (1960), C.A. 55, 1788 (1961). Conformation: Matsui et al., Agric. Biol. Chem. 27, 185 (1963).

Chemical structure

Properties

Shiny granular crystals from water or dioxane. Dec 174°. [α]D16.5 17° (c = 1.8 in 0.01N HCl); [α]D20 16.6° (H2O). Soluble in water, alc, pyridine. Moderately sol in acetone. Slightly sol in glycerol.

Derivative

Sodium salt.

Nomenclature

Sodium erythorbate; Mercate “20”; Neo-Cebitate.

Properties

Crystals, sol in water. pH of aq solns of the sodium salt between 5 and 6. A 10% soln, made from commercial grade, may have a pH of 7.2 to 7.9. The free acid is more sol in water (40 g/100 ml H2O) than the sodium salt (16 g/100 ml H2O).

Use

Antioxidant and antimicrobial agent for foods: Kadin, Osadca, J. Agric. Food Chem. 7, 358 (1959).