Methods for production of calcium, magnesium, and zinc salts of sugar acids

Abstract

To provide a method for preparing calcium, magnesium, and zinc salts of sugar acids.SOLUTION: This method is characterized in that it may include providing a sugar and oxidizing the sugar to a sugar acid in the presence of a noble metal catalyst, oxygen, and a heterogeneous hydroxide source. Preferably the oxidation is carried out with a gold catalyst, and a heterogeneous source of magnesium, calcium, or zinc hydroxide. The oxidation can be performed in a batch or continuous manner.SELECTED DRAWING: None

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 853,52 5, filed on May 28, 2019, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure relates to a process for producing high - purity calcium, magnesium, and zinc salts of sugar acids from sugars, including the oxidation of sugars to sugar acids in the presence of a catalyst and a heterogeneous hydroxide source.

Background Art

[0003] Aldonic acids, and salts of related disaccharides incorporating aldonic acids, are industrially used for various markets. In particular, gluconates are widely used. For example, gluconates are complexing agents and are used in the fiber industry, in detergents, and in concrete. They are food additives in beverages and also in bread and feed. Polyvalent metal salts (gluconates) of gluconic acid are used for highly biologically available mineral supplements in food and feed. Gluconates for food applications and pharmaceutical preparations must be very pure. Monovalent salts of gluconic acid have been prepared by enzymatic oxidation, as in U.S. Pat. Nos. 3,935,071, 4,460,686, 5,897,995, and 6,828,130. Currently, gluconates are industrially produced by fermentation, as in U.S. Pat. Nos. 2,602,768 and

[0004] 6,416,981. The calcium, magnesium, and zinc salts of saccharic acid are described in U.S. Patent No. 3,670,000 by ion-exchanging a monovalent salt with a polyvalent metal salt, as in or by neutralizing gluconic acid or its lactone with a polyvalent metal hydroxide . The biotechnological approach for producing saccharate is complicated by the enzyme specificity or the fermentation conditions for specific molecules and salt concentrations. As a result, the production of polyvalent salts of saccharic acid from biotechnological routes is often inefficient, as described in U.S. Patent No. 7,618,664, Lu, et al., Enzyme and Microbial Technology (1996): 339-342, Ba o, et al., Chemical Engineering Science, 61 65-6170 (2001), and Chinese Patent No. 1,054,161 .

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] Since the biotechnological approach to saccharic acid production is extremely specific to the starting sugar, the enzymes or fermentation conditions that readily produce sodium gluconate from glucose are not at all effective in the oxidation of other sugars to their saccharic acids. Alternatively, noble metal catalysts are widely described in the literature as oxidizing aldoses to the sodium salts of aldonic acids. In particular, gold catalysts have been shown to be very effective for the oxidation of glucose to sodium gluconate, as described by Th eilecke, et al, Catalysis Today, 115-120 (20 07). Galactose is described by Kusema, et al., as oxidizing aldoses to the sodium salts of aldonic acids. In particular, gold catalysts have been shown to be very effective for the oxidation of glucose to sodium gluconate, as described by Th eilecke, et al, Catalysis Today, 115-120 (20 07). Galactose is described by Kusema, et al., as being very effective for the oxidation of glucose to sodium gluconate, as described by Th As described by ChemCatChem, 1789 - 1798 (2011), it is oxidized to sodium galactonate. In these applications, a sugar solution is provided and mixed with a heterogeneous catalyst under pressurized oxygen. A specific alkaline pH in the reaction is maintained during the reaction by the addition of sodium hydroxide solution, and the reaction occurs in only a fraction of the time required for biotechnological oxidation. Furthermore, the resulting product solution contains contaminants associated with fermentation, and this thereby requires less purification for a pure final product. Calcium hydroxide, magnesium hydroxide, and zinc hydroxide are only slightly soluble, and a saturated solution has a concentration of only 1%. Therefore, there is a need in the art for a flexible method for efficiently producing calcium, magnesium, and zinc salts of sugar acids at high

[0006] concentrations and purities. A method for the preparation of calcium, magnesium, and zinc salts of sugar acids is found here, which is an object of the present invention and is characterized by including the following steps: providing sugar, preferably at a concentration greater than 0.5 M; oxidizing the sugar to a sugar acid in the presence of a noble metal catalyst, oxygen, and a heterogeneous hydroxide source. Preferably, the oxidation is carried out using a gold catalyst and a heterogeneous source of magnesium hydroxide, calcium hydroxide, or zinc hydroxide. The

[0007] oxidation can be carried out in a batch or continuous manner. It can be better understood by referring to the detailed description. However, the embodiments are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein may be omitted. are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein may be omitted.

[0008] Definitions As used herein, the term sugar refers to an aldose or a disaccharide containing an aldose having a free aldehyde. Examples of sugars include glucose, galactose, xylose, arabinose, L-threose, lactose, and maltose. are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein may be omitted.

[0009] As used herein, the term sugar acid refers to an aldonic acid, or a disaccharide containing an aldonic acid, and salts thereof. Examples of sugar acids include gluconic acid, galactonic acid, xylonic acid, arabinonic acid, lactobionic acid, and maltiobionic acid. are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein may be omitted. acid) are included.

[0010] As used herein, the term heterogeneous hydroxide source refers to a heterogeneous source of magnesium hydroxide, calcium hydroxide, or zinc hydroxide. are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein

[0011] As used herein, the term heterogeneous source of magnesium hydroxide refers to magnesium hydroxide, magnesium oxide, or magnesium carbonate. are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein

[0012] As used herein, the term heterogeneous source of calcium hydroxide refers to calcium oxide, calcium hydroxide, or calcium carbonate. are not limited to those exemplified below. In certain cases, details not necessary for understanding the embodiments disclosed herein

[0013] As used herein, the term heterogeneous source of zinc hydroxide refers to zinc hydroxide carbonate ([ZnCO ydroxide carbonate)([ZnCO 32 · [Zn(OH) 2 3 of a compound having the formula), zinc hydroxide, or zinc oxide.

[0014] As used herein, the term "oxidation" refers to the conversion of the aldehyde group (-CHO) of a sugar to a carboxyl group (-COOH) by a chemical reaction or physical process.

[0015] As used herein, the term oxygen refers to molecular oxygen (O 2 ). Oxygen can be provided alone or as a component of a gas mixture such as present in the atmosphere.

[0016] Provision of Sugar Sugar is a raw material for the production of sugar salts. Sugar is an easily available compound and can be produced from many raw materials. For example, glucose is generally obtainable from the hydrolysis of starch, lactose can be produced from milk, glucose and galactose can be produced from the hydrolysis of lactose or biomass, and xylose can be produced from the hydrolysis of biomass. The hydrolysis of the raw materials for producing sugar can be carried out commercially either enzymatically or chemically. Other synthetic routes to sugar production are also common. In some embodiments, the sugar can be glucose, galactose, xylose, arabinose, lactose, or maltose. In some embodiments, the sugar can be glucose. In some embodiments, the sugar can be galactose. In some

[0017] embodiments, the sugar can be xylose. In some embodiments, the sugar can be arabinose. In some embodiments, the sugar can be lactose. In some embodiments, the sugar can be maltose.​​ In some embodiments, the sugar can be maltose.

[0018] Preferably, the sugar is provided in a solution at a concentration greater than 0.1 M, more preferably greater than 0.5 M. In some embodiments, the concentration of the sugar can be from about 0.1 M to about 7 M. In some embodiments, the concentration of the sugar can be from about 0.5 M to about 5 M, from about 0.5 M to about 4 M, from about 0.5 M to about 3 M, from about 0.5 M to about 2 M, or from about 0.1 M to about 1 M. In some embodiments, the solution can be an aqueous solution.

[0019] Oxidation of the sugar A method for producing a salt of a sugar acid can include oxidizing a sugar to a sugar acid in the presence of a noble metal catalyst, oxygen, and a heterogeneous source of hydroxide. In some embodiments, the heterogeneous source of hydroxide can be a heterogeneous source of magnesium hydroxide, calcium hydroxide, or zinc hydroxide. Preferably, the noble metal catalyst is a gold catalyst. The sugar acid product is formed as a metal salt combined with the hydroxide used in the reaction.

[0020]

[0021] In some embodiments, the sugar acid oxidation can be carried out in a batch reaction where all of the heterogeneous hydroxide source required for the reaction is added at the start of the reaction.

[0021] In other embodiments, the oxidation of the sugar can be carried out in a batch reaction where a slurry of the heterogeneous hydroxide source and water is metered into the reactants over time.

[0022] In another embodiment, the oxidation of the sugar can be carried out in a continuous reaction where a slurry of either the heterogeneous hydroxide source and water or the sugar solution is added during the reaction. In another embodiment In some embodiments, the oxidation of sugars can be carried out in a continuous reaction, resulting in a sugar to sugar ratio of greater than 1:2. An excess of a heterogeneous hydroxide source that produces a ratio of heterogeneous hydroxide cations to In some embodiments, the ratio of heterogeneous hydroxide cations to sugar is maintained at: The ratio of the heterogeneous hydroxide to the sugar may range from about 1:2 to about 1000:1. The ratio can be about 1:2, about 5:1, about 50:1, or about 500:1.

[0023] In some embodiments, the reaction vessel is pressurized with oxygen to a pressure of about 60 psi to about 200 psi. In some embodiments, the reaction vessel can be pressurized at about 70 psi, about 80 psi, about 90 psi, i, approx. 100psi, approx. 110psi, approx. 120psi, approx. 130psi, approx. 140ps i, or may be pressurized with oxygen to a pressure of about 150 psi.

[0024] In some embodiments, the temperature of the reaction solution may be from about 30° C. to about 70° C. In embodiments, the temperature of the reaction solution may be about 40°C, about 50°C, or about 60°C.

[0025] In some embodiments, the resulting concentration of the salt of the sugar acid in the reaction solution is from about 0.1 M to about 1 In some embodiments, the resulting concentration of the salt of the sugar acid in the reaction solution can be about 0. The concentration may be from about 0.2M, about 0.3M, about 0.4M, or about 0.5M.

[0026] In some embodiments, the oxidation may be carried out as a batch reaction. All heterogeneous hydroxide sources may be added at the beginning of the batch reaction. The heterogeneous hydroxide source may be added during the batch reaction.

[0027] In some embodiments, the oxidation can be carried out as a continuous reaction. For a continuous reaction, a heterogeneous hydroxide source can be added during the continuous reaction. In some embodiments, the reactor can be filled with an excess amount of heterogeneous hydroxide source, and sugar can be continuously fed into the reactor.

Examples

[0028] Example 1 A 0.60 M solution of glucose was provided. A 1-liter pressure vessel was provided, to which the glucose solution was added, along with 4 g per liter of 4.5 wt% gold in the catalyst and 17.5 g per liter of magnesium hydroxide. The reaction vessel was pressurized with 100 psi of oxygen and the temperature was raised to 50 °C. The reactants were stirred for 2.9 hours and then cooled to room temperature and analyzed. The resulting solution had a magnesium gluconate concentration of 0.30 M which constituted a 100% yield.

[0029] Example 2 A 0.68 M solution of glucose was provided. A 1.5-liter pressure vessel was found to be operable in continuous mode. The reactor was filled with 900 ml of the glucose solution, along with 8 g per liter of 4.5% gold catalyst and 19.8 g per liter of magnesium hydroxide. The reaction vessel was pressurized with 100 psi of oxygen and the temperature was raised to 70 °C. After 1.5 hours, the reaction was initiated in continuous mode by the addition of a glucose solution (0.70 M): magnesium hydroxide slurry (19.7 g per liter) at a rate of 5 ml per minute. The product solution was removed from the reaction vessel at a rate of approximately 5 ml per minute. The reaction was allowed to proceed for an additional 5.5 hours. The resulting product solution had a 0.30 M magnesium gluconate It had a magnesium concentration, which constituted a yield of 88%.

[0030] Example 3 A 0.5 M solution of glucose was provided. In five separate experiments, a 1-liter pressure vessel was provided, to which 0.5 liters of the glucose solution was added, and 4 g of a 4.5% gold catalyst and the heterogeneous hydroxide source listed in Table 1 were charged. The reaction vessel was pressurized with 100 psi of oxygen. The reaction temperature and time for each experiment are shown in Table 1 along with the respective glucose conversion and selectivity for each experiment.

Table 1

[0031] All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. The invention can be embodied in many different forms, but specific preferred embodiments of the invention are described in detail herein. The present disclosure is illustrative of the principles of the invention and is not intended to limit the invention to the specific embodiments shown. Additionally, unless otherwise expressly stated, the use of the term "a" is intended to include "at least one" or "one or more". For example, "sugar" is intended to include " at least one sugar" or "one or more sugars". Any range expressed in absolute or approximate terms is intended to cover both, and any definition used herein is intended to clarify and not to limit. Numerical ranges and parameters indicating the broad scope of the invention are approximations, but the specific ones are set forth as precisely as possible.

[0032] Any range expressed in either absolute or approximate terms is intended to cover both, and any definition used herein is intended to clarify and not to limit. Numerical ranges and parameters indicating the broad scope of the invention are approximations, but the specific ones are set forth as precisely as possible. The numerical values shown in the examples are reported as accurately as possible. However, any numerical value necessarily includes certain errors resulting from the standard deviation found in its respective test measurements. Furthermore, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein (including all fractional and integral values). That is.

[0033] Statement 1. A method for producing a salt of a saccharic acid, comprising oxidizing a sugar in a reaction vessel in the presence of a noble metal catalyst, oxygen, and a heterogeneous hydroxide source to produce a saccharic acid.

[0034] 2. The method according to 1, wherein the noble metal catalyst is a gold catalyst.

[0035] 3. The method according to 1 or 2, wherein the oxidation is carried out as a batch reaction and all of the heterogeneous hydroxide source is added at the start of the batch reaction.

[0036] 4. The method according to 1 or 2, wherein the oxidation is carried out as a batch reaction and the heterogeneous hydroxide source is added during the batch reaction.

[0037] 5. The method according to 1 or 2, wherein the oxidation is carried out as a continuous reaction and the heterogeneous hydroxide source is added during the continuous reaction.

[0038] 6. The method according to 1 or 2, wherein the oxidation is carried out as a continuous reaction and the heterogeneous hydroxide source is present in a molar ratio of more than 1:2 with respect to the sugar.

[0039] 7. The method according to any one of 1 to 6, wherein the heterogeneous hydroxide source is magnesium hydroxide, calcium hydroxide, or zinc hydroxycarbonate.

[0040] 8. The heterogeneous metal hydroxide source is magnesium hydroxide, magnesium oxide, or magnesium carbonate The method according to any one of 1 to 7.

[0041] 9. The heterogeneous metal hydroxide source is calcium oxide, calcium hydroxide, or calcium carbonate The method according to any one of 1 to 7.

[0042] 10. The heterogeneous metal hydroxide source is zinc hydroxocarbonate, zinc hydroxide, or zinc oxide, the method according to any one of 1 to 7.

[0043] 11. The sugar acid is an aldonic acid or a disaccharide containing an aldonic acid, the method according to any one of 1 to 10 .

[0044] 12. The sugar acid is gluconic acid, galactonic acid, xylonic acid, arabinonic acid, L-threonic acid, lactobionic acid, or maltobionic acid, the method according to any one of 1 to 11 .

[0045] 13. The reaction vessel can be pressurized with oxygen to a pressure of about 60 psi to about 200 psi, the method according to any one of 1 to 12.

[0046] 14. The temperature of the reaction solution can be about 30 °C to about 70 °C, the method according to any one of 1 to 13 .

[0047] 15. The salt of the sugar acid is zinc gluconate, calcium gluconate, magnesium gluconate, magnesium xylonate, magnesium L-threonate, or magnesium lactobionate The method according to any one of 1 to 14.

[0048] ​​16. The sugar is glucose, galactose, xylose, arabinose, L-threose , lactose, or maltose, and the method according to any one of 1 to 15.

[0049] Furthermore, the present invention encompasses any and all possible combinations of some or all of the various embodiments described herein. It should also be understood that various changes and modifications to the preferred embodiments of the invention described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. Accordingly, such changes and modifications are intended to be covered by the appended claims. ​

Claims

1. 1. A method for producing a salt of a sugar acid, comprising the steps of: The sugar is oxidized in a reaction vessel in the presence of a noble metal catalyst, oxygen, and a heterogeneous hydroxide source. , producing a sugar acid.

2. The method of claim 1 , wherein the precious metal catalyst is a gold catalyst.

3. The oxidation is carried out as a batch reaction and all of the heterogeneous hydroxide source is added to the batch The method of claim 1 , wherein the compound is added at the start of the reaction.

4. The oxidation is carried out as a batch reaction, and the heterogeneous hydroxide source is added during the batch reaction. The method of claim 1 , wherein the

5. The oxidation is carried out as a continuous reaction and the heterogeneous hydroxide source is added during the continuous reaction. The method of claim 1 , wherein

6. The oxidation is carried out as a continuous reaction and the heterogeneous hydroxide source is in a ratio of greater than 1:2 with the sugar. The method of claim 1 , wherein the molar ratio is

7. The heterogeneous hydroxide source is selected from the group consisting of magnesium hydroxide, calcium hydroxide, and carbonate hydroxide. The method of claim 1 , wherein the metal is zinc.

8. The heterogeneous hydroxide source may be magnesium hydroxide, magnesium oxide, or magnesium carbonate. The method of claim 1, wherein the metal is sodium.

9. The heterogeneous hydroxide source is calcium oxide, calcium hydroxide, or calcium carbonate. The method of claim 1, wherein

10. The heterogeneous hydroxide source is zinc carbonate hydroxide, zinc hydroxide, or zinc oxide. Item 1. The method according to item 1.

11. 2. The method of claim 1, wherein the sugar acid is an aldonic acid or a disaccharide containing an aldonic acid. 。

12. The sugar acid is gluconic acid, galactonic acid, xylonic acid, arabinonic acid, L-threonic acid. , lactobionic acid, or maltiobionic acid The method of claim 1 .

13. 4. The method of claim 1, wherein the reaction vessel is capable of being pressurized with oxygen to a pressure of about 60 psi to about 200 psi.

1. The method according to claim 1.

14. The method of claim 1, wherein the temperature of the reaction solution can be from about 30° C. to about 70° C.

15. The salt of the sugar acid is preferably zinc gluconate, calcium gluconate, magnesium gluconate, Magnesium xylonate, magnesium L-threonate, or magnesium lactobionate The method of claim 1, wherein the metal is nesium.

16. The sugar is glucose, galactose, xylose, arabinose, L-threose, The method of claim 1, wherein the sugar is lactose or maltose.

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