Mucic acid, C₆H₁₀O₈ or HOOC-(CHOH)₄-COOH (also known as galactaric or meso-galactaric acid) is an

aldaric acid Aldaric acids are a group of sugar acids, where the terminal hydroxyl and carbonyl groups of the sugars have been replaced by terminal carboxylic acids, and are characterised by the formula HOOC-(CHOH)n-COOH. Synthesis Aldaric acids are usual ...

obtained by

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

oxidation of

galactose Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecu ...

or galactose-containing compounds such as lactose,

dulcite Galactitol (dulcitol) is a sugar alcohol, the reduction product of galactose. It has a slightly sweet taste. In people with galactokinase deficiency, a form of galactosemia, excess dulcitol forms in the lens of the eye leading to cataracts. G ...

, quercite, and most varieties of gum.

Properties

Mucic acid forms a crystalline powder, which melts at 210–230 °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 Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from i ...

carbon atoms (i.e., it is a

meso compound A meso compound or meso isomer is a non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereocenters, the molecule is not chiral. A meso compound is "su ...

Reactions

When heated with

pyridine Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a ...

to 140 °C, it is converted into allomucic acid. When digested with fuming

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

for some time it is converted into αα′ furfural dicarboxylic acid while on heating with barium sulfide it is transformed into a thiophene carboxylic acid. The

ammonium salt The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary ...

yields on dry distillation

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

pyrrol Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4 H4 NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., ''N''-methy ...

and other substances. The acid when fused with caustic alkalis yields oxalic acid. With

potassium bisulfate Potassium bisulfate/ Potassium Sulphate is an inorganic compound with the chemical formula KHSO4 and is the potassium acid salt of sulfuric acid. It is a white, water-soluble solid. Preparation More than 1 million tons were produced in 1985 a ...

mucic acid forms 3-hydroxy-2-pyrone by dehydration and decarboxylation. :

Use

Mucic acid can be used to replace

tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally ...

self-raising flour Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many cultur ...

fizzies Fizzies were tablets that created a "carbonated" soft drink when added to water. History Origin Lem Billings, a close and long-time friend of President John F. Kennedy and the Kennedy family, has also been given credit as inventor. "As Vice Presi ...

. It has been used as a precursor of

adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula (CH2)4(COOH)2. From an industrial perspective, it is the most important dicarboxylic acid: about 2.5 billion kilograms of this white crystalline powder are produced annuall ...

in the way to

nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from pe ...

by a rhenium-catalyzed deoxydehydration reaction. It has been used as a precursor of

Taxol Paclitaxel (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical ca ...

in Nicolaou Taxol total synthesis (1994).

References

{{reflist Sugar acids Monosaccharides

Properties

Reactions

Use

See also

References