D- -Gluconic acid

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

Propose a mechanism to account for the fact that D-gluconic acid and D-man-nonic acid are interconverted when either is heated in pyridine solvent. 

Citric acid and other hydroxycarboxylic acids, such as gluconic acid. Also, derivatives such as sodium gluconate (D-gluconic acid, sodium salt), HOCH2[CH(OH)]4 COONa. 

Electrochemical Decarboxylations Investigated in Micro Reactors Organic synthesis 86 [OS 86] Electrochemical cecarboxylation of D-gluconic acid... 

Figure 4.95 Faradaic current efficiency as electrical charge equivalent for conversion of D-gluconic acid given for two values of average current density. The symbols represent measured conversion and the solid and dashed lines calculated results [65. ...

OS 86] [R 29] ]P 66] On increasing the average electrical current from 1 to 5 A m for the D-gluconic acid decarboxylation, the Faradaic current efficiency increases by a factor of 2-3 [65], At best, a Faradaic current efficiency of about 75% is reached (Figure 4.95). 

OS 86] ]R 29] ]P 66] A model is able to describe experimental results obtained for the electrochemical decarboxylation of D-gluconic acid (1 A mT ) [65]. At an average electrical current of 5 A m the model predicts better performance than is actually achieved. 

Walden inversion on C2 has occurred in one of these sequences if in the first, then chitose, chitonic acid and isosaccharic acid have the configuration of D-mannose if in the second, i. e., in the deamination of 2-amino-D-gluconic acid, then chitaric acid and epi-isosaccharic acid are... 

Further consideration needs to be given to the interesting fact that although D-glucosaminic acid (2-amino-D-gluconic acid) undergoes de-amination. with the establishment of a 2,5-anhydro ring, the deamination... 

Oxidation of Isopropylidene Derivatives of Ketose Sugars. Whenever isopropylidene derivatives can be obtained in which all groups except the primary alcoholic grouping at Cl are blocked this method is undoubtedly the best. It may be illustrated by reference to the preparation of 2-keto-D-gluconic acid from D-fructose.14... 

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. 

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