Gluconic acid, structure

Note D-Gluconic acid and other aldonic acids exist in equilibrium with lactone structures. 

Levi, Hawkins and Hibbert6 have recently confirmed the structure for L. mesenteroides dextran proposed by Fowler, Buckland, Brauns and Hibbert.34 Completely methylated dextran in an over-all yield of 71% was obtained by three methylations with dimethyl sulfate and sodium hydroxide, followed by six modified Muskat methylations. The methylated dextran was hydrolyzed at 140° with methanolic hydrogen chloride, and the mixture of methylated glucosides, obtained in 95% yield, was quantitatively separated by fractional distillation. 2,3-Di-methyl-D-glucose was identified by means of the phenylhydrazide of the corresponding D-gluconic acid. 

Problem 22.27 Fischer prepared L-gulose by oxidizing o-glucose to two separable lactones of glucaric acid. These were reduced to lactones of gluconic acid, which were further reduced. Give all the structures in these... 

It was incorrectly stated in Ref. 6 that the methyl ester of 2-amino-2-deoxy-L-gluconic acid was used, and an incorrect structure for normusearine was given. 

This procedure for chemical equations is very similar to mathematical or physical equations. Please note that the actual reaction is much more complicated. For example, the hydroxy group in the gluconic acid does not come from the water molecule. Glucose in fact usually forms a ring structure instead of the shown linear structure. 

The rates of hydrolysis of the lactones depend on the parent structure for instance, the 1,4-lactone of D-mannonic acid is more stable than that of D-gluconic acid, and the 1,4-lactones of 2-deoxyaldonic acids are more stable than the corresponding aldonolactones. The final attainment of equilibrium between free aldonic acids and their lactones is reached only after many days at room temperature it is, however, accelerated by the presence of strong acids and by heating. A detailed discussion of the formation and hydrolysis of aldonolactones is available in a review by Shafizadeh,59 and the conformations and stabilities of aldonolactones have been discussed by Lemieux.60 Detailed analyses of D-glucono-1,5-lactone and other lactones have been reported.61 13C NMR spectroscopy proved to be a convenient method for monitoring the equilibria.62... 

D-gluconic acid, and D-glucuronic acid. Search Klotho and/or ChemFinder sites for their structures. How would you differentiate these redox derivatives by spectroscopic methods. 

Scheme 10 Structure of hyperbranched poly(ethylene imine) 26 and functionalization of PEI with a glycidol (PEIXGLY), b gluconic acid (PEI GLU) and c lactobionic acid (PEIXLAC)...

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