DK165009B - SACCHAROSE-1,6,6'-TRICARBOXYLIC ACID AND SALTS THEREOF, PROCEDURE FOR PREPARING THEREOF, AND SACCHAROSE-1,6,6'-TRICARBOXYLIC ACID USED IN DETERGENTS - Google Patents

Abstract

Sucrosetricarboxylic acid can be prepared by oxidising sucrose with oxygen, where appropriate mixed with inert gases, using a catalyst which is more efficient than platinum/alumina. The product can be employed in detergents or as food additive.

Description

DK 165009 B

The present invention relates to sucrose-1,6,6 '- tricarboxylic acid and its salts, to a process for preparing said acid and its salts and to the use of the acid in detergents.

It is known that the catalytic oxidation of carbohydrates, especially the oxidation of the primary hydroxymethyl groups contained therein, proceeds slowly and in most cases not uniformly. Thus, for example, oligomeric carbohydrates such as a branched arabinoxylan from rye flour 10 are oxidized in 4 days at 65 ° C only up to 4% for uronic acids. Admittedly, the oxidation of sucrose has also been mentioned, but in this context there is no indication of the isolation of the reaction products. It has only been found that with a total hydrolysis connected it has only been found that the hydrolyzate contains small amounts of glucuronic acid.

The oxidation of sucrose with a platinum-clay catalyst and oxygen has also already been described, cf.

U.S. Patent No. 886,305, Example 3, or the corresponding U.S. Patent No. 2,845,439, Example 4. This oxidation, after 6 hours of treatment, resulted in only 60% of the theoretically expected yield of the corresponding glucuronic acid derivative. However, the isolation of this compound is not disclosed.

The present invention relates to the novel sucrose-1,6,6'-tricarboxylic acid (i.e. (β-D-arabino-furanic acid-2-hexulosyl) -α-D-glucopyranosiduronic acid) of the formula

C00H C00H

30 'kpvT' V3f (i)

In J-γ Lo_ icooH

HAY

B0 OH

35 and salts thereof.

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2

The invention further relates to a process for the preparation of the sucrose-1,6,61-tricarboxylic acid and its salts, the process of which is sucrose by oxidizing it with oxygen, optionally in admixture with inert gases, by means of a catalyst which contains an active carbon platinum metal and is more effective than platinum / clay soil, wherein the catalyst contains 5-10% by weight of metal and the free acid is converted, if desired, into salts thereof, as is known per se. Thus, as catalysts are such 10 of platinum metals, e.g. palladium, but especially the platinum itself, on activated charcoal, primarily the activated types, suitable.

As mentioned, these contain 5-10% by weight of metal, especially platinum. Hereby, in addition to a marked increase in the rate of oxidation, an increased selectivity of the oxidation is obtained between 15 primary and secondary hydroxyl groups of the carbohydrates, especially of non-reduced carbohydrates. Preferably, the oxidation is carried out by treating solid catalyst with gaseous oxygen in an aqueous reaction medium, i.e. in a three-phase reaction. This is carried out e.g. in a blow column column reactor that can be operated both continuously and continuously. In preferred embodiments, highly concentrated oxygen is used and the reaction solution is circulated to make it easier to adjust the pH or keep it constant. One skilled in the art will be able to adjust the reaction solution to a selected or suitable reaction temperature and optimally determine the substrate / catalyst or substrate / oxygen concentration ratio.

The process of the invention is generally carried out at from 30 ° C to the boiling point, preferably at 50-95, 30 especially at 60-90 ° C. In general, atmospheric pressure is worked, although it is also possible to use overpressure, whereby it is possible to increase the amount of oxygen and / or raise the reaction temperature. In the process of the present invention, is it particularly advantageous to comply with certain sucrose concentrations? under 5% by weight overoxidation occurs easily, and above 20% by weight only atmospheric pressure can be obtained

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3 relatively low turnovers. Generally, pH values of 5-9, preferably 6-8, are employed. The course of the reaction can be followed by taking samples, e.g. by gas chromatographic analysis of the derivatized, e.g. silylated 5 products.

The sucrose 1,6,6'-tricarboxylic acid formed generally appears in admixture with less oxidized precursor products, i.e. various mono- and / or dicarboxylic acids. The oxidation can already be interrupted at a content of at least 20% of the tricarboxylic acid. Usually the oxidation is brought to such an extent that at least 30 or 40 are formed and preferably more than 60 or 70% sucrose-1,6,6'-tricarboxylic acid.

This can be concentrated and isolated from the reaction mixture in a manner well known to those skilled in the art.

The method of the present invention can e.g. is carried out in a double jacket reactor in which the suspension of the catalyst is in the aqueous medium and which contains a bottom or a similarly suitable second porous membrane and is flowed from the underside finely distributed by means of this separating membrane. gas stream.

For economic and safety reasons, the oxygen is conveniently passed through the reaction medium at such a rate that the catalytically activated oxygen at the upper end of the blow column is just consumed. To improve the admixture and extend the action time of the oxygen, it may be advantageous to stir the reaction mixture.

The sucrose-1,6,6'-tricarboxylic acid formed is suitable as such or in the form of its immediate reaction products, i.e. especially mixtures with the precursor products, because of its chemical structure for use in complexing agents, e.g. analogous to the gluconic acid and the glucaric acid in detergent preparations. A test of the calcium-binding capacity of sucrose-1,6,6 '-tricarboxylic acid in comparison with the binding capacity of sodium triphosphate shows that the calcium-binding capacity of a sample containing only 32.1% of the active substance sucrose-1.6, 6 '

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4-tricarboxylic acid, is 77 mg CaO grams at 20 ° C, whereas the calcium binding capacity of 100% sodium triphosphate is 159 mg CaO per liter. grams at 20 ° C.

The invention is further illustrated in the following examples.

Example 1 In an externally heated, vertically arranged glass tube (diameter: 50 mm, length: 80 cm) with a fryer bottom and a slightly installed outlet for the reaction mixture, a solution of 120 g sucrose in 1.2 liters water and 60 g added platinum catalyst (5% Pt / active carbon) of an oxygen stream (about 25 Nl / h) from below and upwards. The acids resulting from the oxidation are converted either by the addition of sodium hydroxide solution with the associated pH regulation option or by the corresponding molar amounts of sodium bicarbonate added, in whole or in part, to the sodium salts. At a temperature of 80 ° C at the oxidation and neutralization and a pH which is kept constant at 20 6.5, according to gas chromatographic analysis after silylation, the following compositions are obtained depending on the reaction time (cf. Table I):

Table I 25

Compositions of the oxidation products depending on the reaction time (in percent) 3Q _6__t_12 t_18 t

Sucrose consumed

Monocarboxylic Acids 20.9 5.2 1.5 (2 isomers) 35

Dicarboxylic Acids 38.9 39.6 29.7 (2 isomers)

Tricarboxylic Acid I1) 5.1 22.3 35.3 40

Sucrose-l, 6,6'-tri-carboxylic acid.

5

The reaction solution is filtered from the catalyst, evaporated over a thin-layer evaporator and freeze-dried. Yield 104 g (86.7 wt%). The total acid content is 7.18 mval / g (theoretical value of sucrose-1,6,6 '-tricarboxylic acid 5.80 mval / g).

To characterize the sucrose-1,6,6'-tricarboxylic acid (STA), the reaction mixture is converted by the commercially available cation exchange to the free acids and lyophilized after filtration. After complete acetylation 10 with an excess of acetic anhydride and equimolar amounts of p-toluenesulfonic acid (20 ° C, 20 h), the syrupy residue was chromatographed over silica gel (eluent: methylene chloride / methanol 10: 1 v: v). The pentaacetylated sucrose-1,6,6'-15-tricarboxylic acid thus obtained by polar eluent is converted to the trisodium salt with catalytic amounts of sodium methanolate in methanol.

1 H NMR (D 2 O, 400 MHz): δ = 5.45 (d, H-1 ', J ± if 2 + 3.75 Hz), 4.23--4.12 (m, H-5' , H-3, H-5), 3.82 (structure t, H-3 ', J3if4. = 9.5 Hz, J2 »3» = 9.8 Hz), 3.54 (dd, H -2 ', Ji>, 2, = 3'75 Hz, J2. ^ 3i = 9.8 Hz), 3.45 (Struct. T, H-4', J3 «, 4 i = J4«, 51 = 9.5 Hz).

GC-MS (gas chromatography-mass spectroscopy) (after silylation, chemical ionization with isobutane) m / z = 961 (M + 1-25 fragment of the 8-fold silylated compound, relative intensity about 0.1%).

FAB-MS (Fast Atom Bombardment) (sodium salt used, glycerol as matrix) m / z = 451 (MH +, relative intensity 36%).

Example 2

As described in Example 1, 120 g of sucrose, dissolved in 1.2 liters of water, are oxidized at 60 ° C and pH = 7.5 in oxygen flow. Table II lists the GC analytically determined compositions.

35

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5 6

Table II

Composition of the oxidation products depending on the reaction time (as a percentage) _8 t 28 t 52 t 84 t

Sucrose 1.1 10

Monocarboxylic Acids 28.9 10.3 5.7 4.7 (2 isomers)

Dicarboxylic Acids 35.8 36.1 27.3 23.0 (2 isomers)

Oxalic acid 5.9 10.8 12.6 10.9

Tricarboxylic acid I *) 4.6 20.7 32.7 40.9 20 *) Sucrose-1,6,6 * -tricarboxylic acid.

After filtering off the catalyst and freeze-drying the filtrate, 93.8 g (78.0 wt%) is obtained.

Claims (8)

1. Sucrose-1,6,6'-tricarboxylic acid and its salts. 2. Process for Preparing Sucrose - 1,6,6 * -tricarboxylic acid or salts thereof, known as oxidizing sucrose with oxygen, optionally in admixture with inert gases, by means of a catalyst containing a platinum metal on activated carbon and is more effective than platinum / clay soil, wherein the catalyst contains 5-10% by weight of metal and the free acid is converted, if desired, into salts thereof, if desired. Process according to claim 2, characterized in that the oxidation is carried out in that the solid catalyst in an aqueous reaction medium is treated with gaseous, preferably high-concentrated oxygen. Process according to claim 2 or 3, characterized in that the oxidation is carried out at from 30 ° C to the boiling point, preferably at 50-95 and especially at 60-90 ° C, preferably at atmospheric pressure. Process according to one or more of claims 20 to 4, characterized in that the oxidation is carried out in a liquid reaction medium containing 5-20% by weight of sucrose. Process according to one or more of claims 2-5, characterized in that the oxidation is carried out at a pH of 5-9, preferably 6-8. Process according to one or more of claims 2-6, characterized in that the catalyst is a platinum / activated carbon catalyst. Use of sucrose-1,6,6'-tricarboxylic acid in detergents.