Mucic acid 1371433 176612021 2007-12-08T18:52:40Z Warut 2676502 substances => compounds {{Chembox new |ImageFile=mucic acid structure.png |ImageSize=200px |IUPACName=(2S,3R,4S,5R)-2,3,4,5-tetrahydroxyhexanedioic acid |OtherNames= |Section1= {{Chembox Identifiers | CASNo=526-99-8 | PubChem=3037582 | SMILES=C(C(C(C(=O)O)O)O)(C(C(=O)O)O)O }} |Section2= {{Chembox Properties | Formula=C<sub>6</sub>H<sub>10</sub>O<sub>8</sub> | MolarMass=210.1388 | Appearance= | Density= | MeltingPt= | BoilingPt= | Solubility= }} |Section3= {{Chembox Hazards | MainHazards= | FlashPt= | Autoignition= }} }} '''Mucic acid''', C<sub>6</sub>H<sub>10</sub>O<sub>8</sub> or HOOC-(CHOH)<sub>4</sub>-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 [[natural gum|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 [[Optical rotation|optically inactive]] even though it has [[Chirality (chemistry)|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 [[thiophene|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. [[Image:3-hydroxy-2-pyrone.gif|frame|left|Reaction of mucic acid to 3-hydroxy-2-pyrone with a) [[potassium bisulfate]] 160 [[°C]] / 4 hrs. b) [[hydrochloric acid]] to [[pH]] = 7]]<br style="clear:left;"/> ==References== *{{1911}} [[Category:Sugar acids]] [[Category:Monosaccharides]] [[de:Schleimsäure]] [[es:ácido múcico]]