CS221039B1 - Method of preparation of the d-tagatose - Google Patents

Description

The invention relates to a process for the production of D-tagatose from D-galactose.

C.A. Lobry De Bruyn and W. Alberda Van Ekenstein's isomerization [Rec. Trav. Chim, 14,195 (1895); 16, 257, 262, 274 (1897)], which first prepared D-tagatose from D-galactose using pyridine. This reaction was modified by T. Reichstein, W. Bosshard [Hevl. Chem. Acta 17, 753 (1934)], wherein it used a mixture of pyridine and calcium oxide as isomerizing agent and removed unreacted D-galactose by fermentation using a culture of Saccharomyces cerevisiae Y-30. D-tagatose was obtained in 6% yield. In a yield of up to 80% D-tagatose was prepared by oxidation of the D-talito by a culture of Acetobacter suboxydans [E. L. Totton, H.A. Lardy J .: Am. Chem. Soc. 71, 3076 (1949)]. Preparation of D-tagatose using pyridine or pyridine and calcium oxide, respectively. Oxidation of talitol is difficult to carry out on a preparative scale because working with pyridine while hot is dangerous to health. The preparation of D-tagatose by oxidation of D-talitol is economically disadvantageous since the starting material is more expensive than the end product.

The above-mentioned disadvantages are substantially eliminated by the process for the preparation of D-tagatose according to the invention, which is characterized in that D-galakitosis isomerized in an aqueous environment under the catalytic action of a strong basic anion exchange resin in OH ^- form at a temperature of 30 to 90 ° C. up to 12 hours. From the resulting reaction mixture of D-galactose and D-tagatose, a portion of D-galactose is separated from the crystallization by selective crystallization and D-tagaitose is obtained by salification with a cationic acid which is in calcium form.

The advantage of the proposed process for the preparation of D-tagatosis over the prior art processes is that the process is simpler, economically undemanding and harmless to health.

EXAMPLE

A mixture of 500 g of D-galactose is dissolved in 5 l of water and 0.5 kg of ion exchanger in OH form is added and stirred at 60 ° C for 6 hours. The solution is separated from the ion exchanger by filtration and purified by the addition of 100 g of activated carbon, filtered and the filtrate is concentrated to a syrup which is redissolved by the addition of 500 ml of methanol and left to crystallize at 10 ° C. The crystalline portion of D-galactose is filtered off, concentrated and the crystallization is repeated. Two crystallizations yielded 300 g of D-galactose in 60% yield. The filtrate is concentrated to 80% syrup, dissolved in 360 ml of 50% ethanol and chromatographed on a strong acid ion exchanger in calcium form. 50% ethanol was used as eluent. The reaction mixture was fractionated on a strong calcium ion exchanger column in calcium form having a length of 100 cm and a diameter of 8 cm at a flow rate of 1 ml / min of 50% ethanol eluent to give 103 g of crystalline D-tagatose of mp 124 ^° C. _D ^{20 -} 4.8 (c = 5 in water) in 20.6% yield.

D-tagatosis is a rare keto-sugar and can be widely used in the study of biochemical iprocesses and in medicine.

Claims (1)

SUBJECT Process for the preparation of D-tagatose, characterized in that D-galactose isomerized in an aqueous medium under the catalytic action of a strong basic anion exchange resin in OH-form at a temperature of 30 to 90 ° C for 4 to We claim: After 12 hours and from the resulting reaction mixture of D-galactose and D-tagatose, a part of D-galactose is separated by selective crystallization and D-tagatose is obtained by chromatography on a strong acid cation exchange resin which is in calcium form.