Sugar acids galactaric acid

Hydroxycinnamoyl- CoAs Sugar acids (glucuronate, glucarate, galactarate) Monoesters exact position of the O-ester group unclear 25... 

When an oxidizing agent, e.g. nitric acid, is used, a sugar is oxidized at both ends of the chain to the dicarboxylic acid, called aldaric acid. For example, galactose is oxidized to galactaric acid by nitric acid. 

Arabinose—as could be shown by chain extension and degrading of glucose and mannose—forms a portion of both of these hexoses its configuration can be neither that of ribose, nor that of xylose, because, in contrast to arabinose, these pentoses form inactive dicarboxylic acids. The formula (7) (lyxose) is ruled out for arabinose, since a one-carbon addition to it leads to an inactive (galactaric) acid and an active (talaric) acid. Consequently, D-arabinose must have formula (5) and with that conclusion, (10) had been derived for D-(+)-glucose—but with one restriction. Fischer had to choose between (10) and its enantiomorph he chose (10), and wqs aware of the arbitrary nature of this decision. The same decision fixed the form of all the other series-related sugars represented in Fig. 1. That Fischer had accidentally chosen the correct absolute configuration was not realized until after his death. 

The reaction probably proceeds via the cyclic forms of the sugars and lactones, as equilibria between the various cyclic forms and the acyclic form are presumably established rapidly under the strongly acidic conditions of these oxidations. Thus, D-galactose undergoes oxidation to (acyclic) galactaric acid, whereas similar reaction of D-mannose affords a dilactone (see preceding Chapter). 

Crystallization sugars may easily crystallize. The crystals are usually stable at room temperature, although in general are hygroscopic and they have to be held in a closed vessel. Sugars are present in wines at very low concentration thus they remain soluble. Nevertheless some problems can arise when some insoluble crystals appear, such as mucic acid (galactaric). 

Tetra-O-methyl-D-mannaric and galactaric acids and their bis(pentachlorophenyl) esters have been prepared [99] as crystalline compounds, in good yields, from D-mannitol and galactitol, respectively. A new stereoregular fully sugar-based polyamide, analogous to Nylon 66, has also been prepared [99] by polycondensation of bis(pentachlorophenyl) 2,3,4,5-tetra-O-methyl-D-mannarate with l,6-diamino-l,6-dideoxy-2,3,4,5-tetra-<9-methyl-D-mannitol dihydrochloride [100]. 

Simple esters of the sugar acids, as ethyl D-mannonate 102) and diethyl galactarate 103), have long been known (Chapter VI). n-Galacturonic acid occurs in pectins largely esterified with methanol 104), Many of the methyl esters of the 0-acetyl aldonic acids have been obtained by the action of diazomethane upon the fully acetylated aldonic acids. Penta-0-acetyl-D-gluconates of some of the alditols (XVIII) and of cellulose have been described 106), The methyl acid ester of di-0-acetyl-L-(dea ro)-... 

Saladini M, Menabue L, Ferrari E (2001) Sugar complexes with metaF+ ions thermodynamic parameters of associations of Ca, and Zn + with galactaric acid. Carbohydr Res 336(1) 55-61. doi 10.1016/S0008-6215(01 )00243-9... 

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