Gluconic Acid Process

New Gluconic Acid Process The biomass based gluconic acid production... 

The ability of bacteria - particularly Pseudomonas spp. and Glucottobader spp. - to produce gluconolactone and gluconic acid has been exploited and the process is used commerdally, mainly in the production of the lactone. 

A reaction of practical importance is the oxidation of a carbohydrate aldehyde group to a carboxyl group. This is the basis for a process converting glucose to calcium gluconate, a substance of pharmaceutical interest. The oxidation reaction occurs at graphite electrodes in the presence of the Brj/Br" redox system. Calcium salt is added to the solution to prevent further oxidation of free gluconic acid. 

Moreover, the compound (LV) obtained from the reaction of 2-keto-D-gluconic acid with o-phenylenediamine28 has been dehydrated to give a compound which Maurer erroneously described as LYI. In this case, also, the process of dehydration has been shown to be equivalent to that just described for compound L. The product obtained by interaction of 2-furyl-... 

The process in Example 12-7 was conducted by initially adding 0.35 mol glucose to the 100-L reactor, and replenishing the reaction with 0.28 mol flesh glucose every 144 h for 30 days. Determine the gluconic acid and glucose concentration-time profiles in the reactor over this period... 

During the process described in problem 12-17, it was discovered that the enzyme used to produce gluconic acid was subject to deactivation, with a half-life of 12 days. It appears that the deactivation process is first-order, such that decreases exponentially with time. 

Gluconic Acid. A process to convert lactose to gluconic acid and galactose has been reported (Zadow 1984). Lactose is treated under acidic conditions with bromine, and galactose is recovered from the product concentrate by crystallization. 

Palladium is superior to platinum with respect to both activity and selectivity in this process. More recently, bi- (e.g. Pd, Bi/C)37 and trimetal lie (Pd, Pt, Bi/C)38 catalysts have been described that afford very high selectivities to gluconic acid. For example, Degussa workers38 obtained gluconic acid in 96% selectivity using a 4% Pd, 1% Pt, 5% Bi-on-charcoal catalyst at pH 10, 55°C and 10 mbar 02 pressure. Pt enhances the activity and Bi the selectivity of the Pd catalyst. 

When a stable baseline is reached, transfer an appropriate aliquot of the gluconic acid stock solution into the electrochemical cell, and measure the current until the steady-state current is reached. Repeat this process as many times as necessary. 

As with platinum, the palladium-catalyzed oxidation of anomeric hydroxyl groups in aldoses is a rather selective process.84 The influence of pH in the Pd-catalyzed oxidation of glucose has been studied. It was observed that the gluconic acid formed, in its free form, reversibly inhibits the oxidation process in acidic media.85 The oxidation of D-glucose has been performed with palladium-on-alumina and with bismuth-containing palladium-on-charcoal in water.85 The selectivity in the air oxidation of... 

The oxidation of secondary hydroxyl functions to the carbonyl group is often an undesired side reaction. However, the oxidation of D-gluconic acid to 2-oxogluconic acid is a highly selective process (97% yield) when a Pt-Bi catalyst is employed.89 Such a procedure is of industrial interest. 

---