PROCEDURE FOR THE PRODUCTION OF ISOMALTITOL

Abstract

Improved process for the manufacture of isomaltulose by hydrogenation of isomaltulose. According to the process, a solution of isomaltulose having a concentration of 20-50% by weight is hydrogenated at a temperature between 80 and 130%°C using a catalyst selected from ruthenium, nickel, and mixtures thereof on an inert support at a pressure below 50 atmospheres, the pH being maintained between 3 and 8. The resulting product is substantially free of other polymers. Among the advantages of the process is that it allows the desired ratio of the two isomers β-Glucopyranosyl-1, 1-Mannitol (GPM) and β-Glucopyranosyl-1, 6-D-Sorbitol (GPS) to be achieved.

Description

23.G6212.12. IT.1 gm DESCRIPTION Mf 95 to 00 5 2 28 attached to a patent application for INVENTION INDUSTRIAL titled: "PROCEDURE FOR THE PRODUCTION OF ISOMALTITOL" in the name of: GADOT BIOCHEMICAL INDUSTRIES LTD. of Israeli nationality, with registered office at 117 Hahistadrut Rd, Haifa Bay, Israel. Deposited at No. -ooo- DESCRIPTION The present invention relates to a process for the production of polyols. In particular, the invention relates to an improved process for the production of isomaltulose by hydrogenating isomaltulose. Sucrose is considered the starting substance for the manufacture of isomaltulose. Isomaltulose can be further hydrogenated in an aqueous or neutral alkaline solution, in presence of a catalyst, to produce isomaltitol. Platinum and palladium have been used with good The respective amount required is less than the amount of nickel needed as a catalyst. However, all these catalysts show highly efficient conversion only at a reaction temperature above 160 °C and a pressure above 160 atmospheres, which is a serious inconvenience from a technological point of view. According to British patent No. 0 1,429,334, isomaltol is obtained by hydrogenation of an isomaltulose solution. As mentioned, the starting solution should have a concentration between 35 and 40% by weight, in the presence of P.aney nickel as catalyst, at a pH of at least 9.0, a pressure in the range of 30 100 atmospheres and a temperature in the range of 129°C. In the patent German N 2,520,173 mixtures Of glucopyranesyl mannitol and glucopyranosyl sorbitol are obtained from a solution Of isomaltulose having a higher concentration 50% weight For hydrogenation a medium neutral in presence nickel Raney as catalyst to one Of about atmospheres. In the patent US No. 2.8 68,847 he comes A process for the production of polyalcohols by hydrogenation of mono- and disaccharides is described. The process is carried out at a pressure between 7 and 105 atmospheres and a temperature of 50-400°C, using a catalyst selected from the group comprising ruthenium, ruthenium oxide, or ruthenium mixed with platinum, on carbon or alumina supports. One of the main disadvantages of all known processes for obtaining isomaltulose is the non-selectivity of the hydrogenation to achieve the desired preferred ratio of glucopyranosyl-mannitol to glucopyranosyl-sorbitol. Furthermore, the known hydrogenation of isomaltulose requires a relatively long reaction time at very high pressure to achieve optimal yield. An object of the present invention is to provide a process for the manufacture of isomaltitol by hydrogenation of isomaltulose. Another object of the present invention is to provide a process for the manufacture of isomaltulose, in which a predetermined ratio between the two isomeric components, tt-D-Glucopyranosyl-1, 1-D- Marmitelo (hereinafter referred to as GPM) and D-Glucogyronosyl, 6-D-Sorbitol (hereinafter referred to as GPS). The invention relates to a process for the manufacture of isomaltulose by hydrogenation of an isomaltulose solution having a concentration between 20 and 50% by weight, at a temperature between 80 and 130 °C, using a catalyst selected from ruthenium, nickel and mixtures thereof, on an inert support, the pressure exerted being below 50 atmospheres and the pH between 3 and 8. It was found that in these critical conditions 1 'isomaltitol produced is substantially free of other polyols, with hydrogenation being completed in less than about 3 hours. An important advantage of the invention is that it allows the desired ratio between the two isomeric forms to be achieved. In the drawings: Figure 1 illustrates the correlation of the conversion of isomaltulose to isomaltitol as a function of temperature. - Figure 2 illustrates the rate of conversion to isomaltitol as a function of the amount of catalyst. - Figure 3 illustrates the rate of conversion to isomaltol as a function of the pressure exerted during hydrogenation. Isomaltitol, a polyalcohol consisting of the two above-mentioned polyols: GPM and GPS, is obtained, according to the present invention, at a weight ratio between 38:62 and 62:38, which is the preferred product known on the market. 1 Various parameters influencing the reaction of hydrogenation have been studied extensively in order to find the main factors governing this reaction to obtain the above-mentioned ratio between the two polyols. It has been surprisingly found, according to the present invention, that an increase in the reaction temperature above 130 °C, mentioned in the prior art, will substantially affect the quality of the product isomaltitol by modifying the ratio between the two polyols. Therefore, in the above-mentioned US Patent No. 2,868,847 (column 1, lines 67-69), it was suggested to obtain hydrogenation even at a temperature above 200 °C, specifying That high temperatures are useful in a continuous process, which is the best in a plant industrial. However these high temperatures danger caramelization. In the attached figure 1, it is reported a graph That correlates 1st extension from the conversion of isomaltulose into isomaltitol how it works of the temperature. How is it? can observe, at a temperature of 100 C said conversion is 1*82% approximately, reaching beyond the at a temperature bug^o2 of 120 °C. It has also been found that the use of a pressure below 50 atmospheres, rather than up to 100 atmospheres suggested in the previous technique, it is sufficient for the system according to the present invention in order to achieve very high conversion rates. Furthermore, this is also a significant advantage from a technological standpoint. It was found that the preferred pressure was in the range of 10 - 20 atmospheres. As can be seen from Figure 3, after 45 minutes at a pressure of 20 atmospheres, a conversion of approximately 83% is achieved, while at a pressure of 25 atmospheres, maximum conversion is achieved. The particular catalyst used has a significant influence on hydrogenation on the reaction. Therefore, in the previous technique Platinum and palladium are mentioned as preferred for this hydrogenation, due to their small amounts required for the reaction. However, it has been found, according to the present invention, that their use has a negative impact on the ratio between the two polyols of isomaltol. The most preferred catalyst useful for the present invention is ruthenium as an inert support, the required amount being between 0.28 and 1.1% by weight of the reactants. The ruthenium may not be absolutely pure and may contain small amounts of other metals. It has also been found that a mixture of ruthenium and nickel is useful for this hydrogenation. The correlation between the amount of catalyst and the conversion rate is clearly seen in the attached figure 2, which shows that with a catalyst amount of only 0.86% a conversion to isomaltitol of over 1*85% is obtained. These amounts of catalyst according to the present invention are much lower than those used with other suggested catalysts, such as Raney nickel, where the amounts used are in the order of 3 - 10%. Therefore, the above mentioned British Patent No. 4 1,429,334 mentions for example even an amount of 8% of this catalyst. The inert support for the catalyst can be chosen from alumina, carbon, silica, earth diatomaceous earth zeolites and the like, the preferred one being carbon. Another advantage of the process according to the present invention is the fact that the pH in the system is between 3 and 8 and generally between 4 and 6, while according to the previous technique the pH must be maintained between 7 and 9 by adding reagents strangers. The isomaltitol solution is purified, after filtering the residual catalyst, with activated carbon or with an ion exchange process. At a concentration above 906, evaporation will yield a fusion product. which could be a crystalline product. Isomaltitol is a white, odorless substance with a melting point of between 100 and 150°C. It is considered a melting point agent. later transformed into appears as a non-hygroscopic, having 14 5 and 155 °C. Being low calories in sight of its sweetening property, it is used with success for many purposes, such as sweets, ice cream, dairy products, baked goods, prepared foods preserves and fruit, etc. In particular, it is used as a dietary and non-dietary food, as well as a carrier for artificial sweeteners. The invention will be illustrated below by some examples, keeping in mind that these examples are given only for a better understanding of the invention without limiting the scope covered by the attached claims. An expert in the technique can insert small variations in the description of said examples, without departing from the attached claims. In the following examples, the concentrations mentioned are given by weight, unless otherwise specified. EXAMPLE 1 The following reagents were introduced into an autoclave under stirring: 325 g water; 125.6 g isomaltulose, and 1.58 g ruthenium on carbon (dry basis) as a catalyst. The autoclave was closed, purged with nitrogen and then hydrogen gas was introduced until 16 atmospheres. The temperature was raised to 120°C. The reaction ceased after 60 minutes, resulting in complete conversion to isomaltitol, consisting of 42.9% GPM and 57.1% GPS. EXAMPLE 2 The following reagents were introduced into an autoclave under stirring: 325 g water; 125.6 g isomaltulose, and 1.9 g ruthenium at 5% on carbon (dry basis), as a catalyst. The autoclave has been closed purged nitrogen and so it was introduced hydrogen up to 16 atmospheres. The temperature was flow rate at 120 c C. The reaction has ceased after 90 minutes, getting a complete conversion in isomaltitol, consisting of 47.8% GPM and 52.2% GPS. EXAMPLE 3 They were introduced the following reagents in an autoclave under agitation: 227.6 g water, 91.4 g isomaltulose, and 0.86 g ruthenium at 5% carbon (dry basis) 1.83 g 54% nickel on carbon as catalysts. The autoclave was closed, purged with nitrogen, and then hydrogen was introduced up to 16 atmospheres. The temperature was raised to 120°C. The reaction ceased after 120 minutes, resulting in complete conversion to isomaltitol, consisting of 56.1% GPM and 43.9% GPS. EXAMPLE 4 The following reagents were introduced into an autoclave under stirring: 275 g water; 225 g isomaltulose, and 1.25 g 5% ruthenium on carbon (dry basis) as catalyst. The autoclave was closed, purged with nitrogen, and then hydrogen was introduced to 16 atmospheres. The temperature was raised to 120°C. The reaction ceased after 45 minutes, resulting in complete conversion to isomaltitol, consisting of 46.3% GPM and 53.7% GPS. EXAMPLE 5 The following reagents were introduced in an autoclave under agitation: 443 g water; 110 g isomaltulose, and 1.39 g ruthenium at 5¾ carbon (dry basis) and 0.55 g nickel (54%) on carbon, as catalysts. The autoclave was closed, purged with nitrogen, and then hydrogen was introduced up to 10 atmospheres. The temperature was raised to 120°C. The reaction ceased after 150 minutes, resulting in complete conversion to isomaltitol, consisting of 50.5% GPM and 49.5% GPS. EXAMPLE 6 The following reagents were introduced into an autoclave under stirring: 700 g water; 300 g isomaltulose, and 1 g ruthenium at 5% on carbon (dry basis) as a catalyst. The autoclave was closed, purged with nitrogen, and then hydrogen was introduced up to 14 atmospheres. The temperature has been raised to 100 Q C. The reaction ceased after 90 minutes, resulting in a complete conversion to isomaltitol, consisting of 44.15 GPM and 55.95 GPS.

Claims

CLAIMS 1. Process for the manufacture of isomaltulose by hydrogenation of a solution of isomaltulose having a concentration of between 20 and 50¾ by weight, at a temperature of between 80°C and 130°C, using a catalyst selected from ruthenium and nickel and They mixtures on an inert support, the pressure exercised being under 50 atmospheres and the pH being between 3 and 8.

2. Process according to claim 1, characterized in that the weight ratio between the two polyols OJ-D-Glucopyranosyl-1, 6-D-Mannitol (GPM) and aD-Glucopyranosyl-1, 6-Sorbitol (GPS) is in the range from 38:2 to 62:

38.

3. Process according to claim 1 or 2, characterised in that said hydrogenation is obtained at a temperature of approximately 100 °C.

4. Process according to claims 1-3, characterised in that the pressure prevailing during hydrogenation is between 10 and 30 atmospheres.

5. Process according to claims 1-4, characterised in that the pH in the system is between 4 and 6.

6. Process according to claims 1 characterized by the Done that the preferred quantity of catalyst is in the range between 0.28 and 1.1% weight of reagents.

7. Procedure according to the claim characterized by the the fact that said catalyst an inert support chosen from alumina.

8. Procedure for isomaltitol, essentially carbon, silica and manufacturing of as specified in the description and claimed in any of the previous claims. More about the Company: GADOT BTOC HEMICAL IN: STRIES Ltd. 9 JUNE IMS THE MANDATORY Ina. Luaa yUtTO Registered in Atoo-ton it n. 556