CS260391B1 - Molybdenum ion catalyzed aldose epimerization agent - Google Patents

Abstract

The purpose of the composition for inhibiting the epimerization of aldoses catalyzed by molybdate ions is to improve the methods of preparing aldoses by reactions catalyzed by molybdate ions, i.e. to simplify and economize these methods of preparation. The stated purpose is achieved by adding citric acid) to the reaction solutions of aldoses with molybdate ions or reaction mixtures of aldose derivatives with molybdate ions, so that the aldoses cannot epimerize. The composition for inhibiting the epimerization catalyzed by molybdate ions has applications in organic chemistry.

Description

260391

The present invention relates to a composition for the inhibition of the dimerization of aldoses catalyzed by the aminobutane ions.

Aldoses are epimerized in weak acidic aqueous solutions in the presence of molybdenum ions to form C-2-epimeric aldoses [V. Bílik: Chem. Lists 77, 496 (1983)]. The molybdenum ionic catalyst component is also utilized by the re-stereoselective hydroxylation of glycals corresponding to aldoses with the cis-arrangement of hydroxyl groups on the carbon atom C-2 and C-3 [V. Bilik: Chem. Rumors 26, 76 (1972)], by oxidative decomposition of 1-deoxy-1-nitroaldito to the corresponding aldoses [V. Bilik: Coll.Czechoslov. Chem. Commun. 39, 1621 (1974)] and the oxidative degradation of phenylhydrazones of aldoses to the corresponding aldoses by a day carbon atom [V. Bílik. P. Biely, M .; Matul: Chem. Rumors 33, 782 (1979)].

The polybenzene ion catalyzed epimerization reaction is reversible. Thus, when isolating the aldoses obtained by the reaction-catalyzed molybdenum ionic moieties, molybdenum ions are not present. There are known methods for removing polybenzene ions on anion exchangers, the disadvantages of which are the large dilution of the solution solutions and the high energy consumption of the thickened solutions. The complete inhibition of the epimerizing reaction catalyzed by molybdenum aniones has not been known to date.

SUMMARY OF THE INVENTION The present invention is based on the use of citric acid as an agent for inhibiting the epimerization of aldoses catalyzed by polybenzene ions. The advantage of the proposed composition for inhibiting the epimerization of aldoses by catalyzed molybdenum ions is that it is not necessary to remove the polybenzene ions, most frequently by extinguishing them, followed by densification of the solution, thus saving on wages, materials, energy and substantially saving the use of evaporator, column installations. EXAMPLE 1 29.7 g (0.15 mol) of D-glucose monohydrate, 0.37 g (3.times.10@-4 moles of heptamolybdenum hexahydrate (i.e., 2.1 .mu.l of 3 mol of molybdenum) are dissolved in 100 ml of water. 3.09 g (1.47, 10 2 moles) of citric acid monohydrate (molar ratio of citric acid to molybdenum in oxidation stage VI is 7: 1), and make up to 150 ml with water. and heated at 90 ° C for 3 hours, 50 mL of 96% ethanol and 16.2 mL (0.165 mol) of phenylhydrazine are added to the cooled solution, and the solution is left to stand at 23 ° C for 20 h. 0.1 g of the phenylhydrazone D-mannose, which is a D-mannose yield of 0.3%, based on the starting D-glucose.

The procedure is as in Example 1, except that 0.44 g (2.1.10 3 mol) of citric acid monohydrate is dissolved (1: 1 molar ratio of citric acid to molybdenum in oxidation stage VI) . 9.4 g of D-mannose phenylhydrazone are filtered off, which represents a 23.3% yield of D-mannose relative to the starting D-glucose. Example 3 Dissolve 3 g (2.10 3 mol) of L-arabinose, 49.4 mg (4.10'5 mol) of hexa-ammonium heptamolybdate tetrahydrate (ie 2.8. Moles of molybdenum) in 20 ml of water. 0.59 g (2.8 x 10 3 mol) of citric acid monohydrate (molar ratio of citric acid to molybdenum in oxidation stage VI is 10: 1). The mixture was heated at 100 ° C for 5 h. Inhibition of L-arabinose epimerization by paper chromatography (What-man Nol) using an elution system of,: acetone, 1-butanol and water at a volume of 7: 2: 1 and elution system B: 1 - butanol, ethanol and water 5 : 1: 4, with an elution rate of 18 to 20 hours followed by detection with aniline hydrophthalate The chromatographic data shows the presence of L-arabinose and the presence of L-ribose in trace amounts. -arabinosis in elution system A: 1.41 and vB: 1.30 and for L-ribose in elution light MEA 2.13, and B: 1.90. EXAMPLE 4

A mixture of 25.5 g (0.1 mol) of N-phenyl-D-mannitylamine, 0.25 g (2.10 µmoles) of heptamolybdate hexaammonium tetrahydrate, 1.18 g (5.6, 10 'moles) of monohydrate cy citric acids (molar ratio of citric acid to molybdenum in the V1 oxidation stage is 4: 1), 15.8 ml (0.2 moles) 35% w / w aqueous formaldehyde solution, 35 ml 96% ethanol and 190 ml water is heated for 3 h at 90 DEG C. Chromatographic recording shows the presence of D-mannose and the presence of D-glucose in the trace amount of D-glucose 1.00 for D-mannose in the A: 1 elution system , 31 and in elution system B: 1.30 Example 5

The procedure is as in Example 3 except that starting from a mixture of 22.5 g (0.1 mol) of N-phenyl-D-ribozylamine, 25 mg (2. 10 -5 mol) of hexammonium heptamolybdate tetrahydrate 118 mg (5.6.104 mol) of citric acid monohydrate (molar ratio of citric acid to molybdenum in oxidation stage VI is 4: 1), 15.7 ml of formaldehyde, 35 ml of 96% w / w. % ethanol (0.2 mol) 35 wt. aqueous solution and 190 ml of water. The chromatographic record shows the presence of D-ribose and in the trace

Claims (1)

Use of citric acid as a means for inhibiting molybdenum ion catalyzed epimerization of aldoses.