Methods for the production of high purity glucaric acid

Abstract

A method of preparing high purity glucaric acid comprising introducing a mixture comprising glucaric acid and one or more sugar oxidation products to a reactive crystallization unit under conditions suitable for formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid. A method of preparing high purity glucaric acid, comprising introducing glucose to a reactor system comprising at least one oxidation reactor and at least one crystallization unit wherein the glucose when disposed in the oxidation reactor is subjected to conditions suitable for the formation of one or more glucose oxidation products and wherein the one or more glucose oxidation products when disposed in the crystallization unit is subjected to conditions suitable for the formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.

Description

METHODS FOR THE PRODUCTION OF HIGH PURITY GLUCARIC ACIDCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application Serial No. 63 / 517,608 filed August 4, 2023 entitled “METHODS FOR THE PRODUCTION OF HIGH PURITY GLUCARIC ACID,” which is incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.FIELD

[0003] The present disclosure relates generally to systems and methods for the purification of carboxylate compounds. More particularly, the present disclosure relates to the production of high purity glucaric acid.BACKGROUND

[0004] Glucaric acid, also known as saccharic or D-glucaric acid, is an organic sugar acid naturally found in various fruits such as oranges, apples, grapefruits, and tomatoes; and vegetables such as cabbage and broccoli. Glucaric acid has potential applications in food, pharmaceutical and polymer industries yet no methodology exists within the public domain for isolation of this key bio-derived platform molecule as a pure, crystalline solid.

[0005] Some of the most widely employed reactions for commercial production of glucaric acid are (i) nitric acid oxidation of glucose and (ii) transition metal-catalyzed glucose oxidation. The nitric acid oxidation of glucose, which was first reported in the 19th century, generates a significant amount of hazardous nitrogen oxide (NOx) gas and is highly exothermic. In commercial production, the amount of heat generated during the nitric oxide facilitated oxidation has to be appropriately dispersed or controllability issues may arise. The transition metal-catalyzed oxidation reactions involves the oxidation of glucose or gluconic acid under high pressure and produces as an intermediate bio-based adipic acid.

[0006] A microbial method of producing high-purity glucaric acid was developed using a catalyst cocktail including, a S. cerevisiae myo-inositol-1 -phosphate synthase, amouse myo-inositol oxygenase, and a P. syringae uranate dehydrogenase. Microbial methods can suffer from product separation issues leading to high chemical costs and limiting these methods use as a means for producing commodity chemicals. Accordingly, an ongoing need exists for improved methods of producing high purity glucaric acid.SUMMARY

[0007] Disclosed herein is a method of preparing high purity glucaric acid comprising introducing a mixture comprising glucaric acid and one or more sugar oxidation products to a reactive crystallization unit under conditions suitable for formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.

[0008] Also disclosed herein is a method of preparing high purity glucaric acid, comprising introducing glucose to a reactor system comprising at least one oxidation reactor and at least one crystallization unit wherein the glucose when disposed in the oxidation reactor is subjected to conditions suitable for the formation of one or more glucose oxidation products and wherein the one or more glucose oxidation products when disposed in the crystallization unit is subjected to conditions suitable for the formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.BRIEF DESCRIPTION OF DRAWINGS

[0009] For a detailed description of the aspects of the disclosed processes and systems, reference will now be made to the accompanying drawings in which:

[0010] Figure 1 is a block flow diagram of an exemplary aspect of a method for production of a liquid mixture of gluconic acid and glucaric acid.

[0011] Figure 2 is a block flow diagram of an exemplary aspect of the present disclosure for production and purification of glucaric acid by reactive crystallization.

[0012] Figure 3 is a block flow diagram of an exemplary aspect of methods of the present disclosure for production and purification of glucaric acid by reactive crystallization and ion exchange chromatography.

[0013] Figure 4 is a block flow diagram of an exemplary aspect of the present disclosure for purification of glucaric acid from a mixture of glucaric acid and gluconic acid through formation of the potassium salts.

[0014] Figure 5 is a block flow diagram of an exemplary aspect of the present disclosure for purification of glucaric acid from a mixture of glucaric acid and gluconic acid through formation of corresponding potassium or calcium salts.

[0015] Figure 6 is the high pressure liquid chromatography mass spectra (HPLC-MS) of a mixture of gluconic acid and glucaric acid.

[0016] Figure 7 is the HPLC-MS of the precipitate obtained after addition of potassium hydroxide to the mixture of gluconic acid and glucaric acid .

[0017] Figure 8A is a 3D surface plot of the saturation concentration as a function of temperature and pH for potassium glucarate.

[0018] Figure 8B is a 3D surface plot of the saturation concentration as a function of temperature and pH for potassium gluconate.

[0019] Figure 8C is a 3D surface plot of the saturation concentration as a function of temperature and pH for a mixture of potassium gluconate and potassium glucarate.

[0020] Figure 9 is a particle size distribution profile for a glucaric acid sample purified as disclosed herein.DETAILED DESCRIPTION

[0021] Disclosed herein are methods for the purification of glucaric acid. It is depicted and contemplated that the intermediates formed herein, termed glucose oxidation products, comprise compounds such as a gluconate, gluconic acid oxidation products, n-keto-acids, C2 to C6 diacids or a combination thereof. In one or more aspects, the reactions disclosed herein form a product mixture comprising gluconic acid, glucaric acid, salts thereof or combinations thereof.

[0022] In an aspect, a method of the present disclosure comprises (i) isolation of a glucarate salt from a product mixture by selective precipitation, (ii) reactive crystallization of the glucarate salt or combinations of (i) and (ii). Thus, the present disclosure contemplates formation of an insoluble salt of the target compound (glucaric acid) and recovery of the insoluble salt. In one or more aspects, the recovered insoluble salt may be used without further processing or may be subjected to additional purification procedures.

[0023] In one or more aspects, a product suitable for use in the present disclosure comprises at least two carboxylic acids, at least two carboxylates or combinations thereof. In one or more other aspects, a product suitable for use in the present disclosure comprises at least two compounds produced by the oxidation of glucose.The oxidation of glucose may be carried out using any suitable methodology. In an aspect, glucose oxidation is carried out via a chemoenzymatic process. For example, the oxidation of glucose may be carried out in the presence of oxygen and an enzyme catalyst (e.g., glucose oxidase (GOX)) and a transition metal catalyst to form a product comprising glucaric acid and gluconic acid as disclosed in U.S. Patent Application Publication No. 2023 / 01211990.

[0024] In an aspect, the product comprising glucaric acid and gluconic acid has a ratio of glucaric acid to gluconic acid of from about 1 :10 to about 10:1 , or from about 2:10 to about 10:2, orfrom about 4: 10 to about 10:4, alternatively from about 5: 10 to about 10:5, or about 1 :10, 1 :5, 1 :2, 1 :1 , 2:1 , 5:1 , or 10:1.

[0025] In an aspect, a method of the present disclosure comprises separation of gluconic acid from glucaric acid by selective precipitation. In such aspects, the gluconic acid and glucaric acid are deprotonated to form the corresponding carboxylate. Deprotonation of gluconic acid and glucaric acid may be carried out by increasing the pH of the product to mixture from about 0.5 to about 7, orfrom about 0.5 to about 5 or from about 2 to about 4 orfrom about 1 to about 6 orfrom about 2 to about 7 using any suitable methodology such as the addition of a base. The resulting mixture is termed a pH adjusted-product mixture.

[0026] In one or more aspects, a potassium salt is added to the pH adjusted-product mixture under conditions suitable for the formation of potassium glucarate and potassium gluconate. Any potassium salt compatible with the presently disclosed subject matter can be utilized. For example, the potassium salt may be potassium chloride, potassium acetate, potassium hydroxide, potassium iodide, potassium bicarbonate, potassium carbonate or combinations thereof. In an aspect, the potassium salt is potassium hydroxide.

[0027] Potassium salt can be added to the pH-adjusted product mixture to provide a final amount of potassium salt ranging from about 2 weight percent (wt.%) to about 60 wt.%, orfrom about 2 wt.% to about 25 wt.%, orfrom about 5 wt.% to about 45 wt.%, or from about 20 wt.% to about 60 wt.% or about 2wt.%, about 4wt.%, about 5wt.%, about 7.5 wt.%, about 10 wt.%, about 12.5 wt.%, about 15 wt.%, about 17.5 wt.%, about 20 wt.%, about 22.5 wt.%, about 25 wt.%, about 27.5 wt.%, about 30 wt.%, about 32.5 wt.%, about 35 wt.%, about 37.5 wt.%, about 40 wt.%, about 42.5 wt.%, about 45 wt.%, about 47.5 wt.%, about 50 wt.%, about 52.5 wt.%, about 55 wt.%, about 57.5 wt.%, or about 60 wt.%. about based on the total weight of the mixture. Hereinafter, all weightpercentages are based on the total weight of the composition disclosed unless indicated otherwise.

[0028] It is contemplated that addition of a potassium salt to the pH-adjusted product mixture will result in free potassium ions that then form a salt with the glucarate and gluconate anions. Potassium glucarate has a solubility in aqueous fluids of approximately 50 g / l while potassium gluconate has a solubility in aqueous fluids of approximately 833 g / l. The methods of the present disclosure utilize this large difference in solubility to effect separation of the salts. Specifically, introduction of the potassium salt to the pH-adjusted product mixture results in formation of an insoluble glucarate salt which precipitates while potassium gluconate remains in solution. Additional techniques may be utilized to facilitate precipitation of potassium glucarate such as agitation, seeding with potassium glucarate crystals, or reduced temperature.

[0029] The resulting pH-adjusted mixture comprises a precipitated potassium glucarate and soluble potassium gluconate. Precipitated potassium glucarate may be separated from potassium gluconate using any suitable solid-liquid separation technique. Nonlimiting examples include sedimentation, centrifugation, filtration, and mechanical separation.

[0030] In an aspect, potassium glucarate precipitates are converted to high purity glucaric acid by acidification of the compound. Acidification of the potassium glucarate precipitate may be carried out by solubilization of the precipitate in an acid such as HCI, sulfuric acid, phosphoric acid, or citric acid, at sufficient acid concentrations that lead to the disclosed pH ranges. Glucaric acid formed after selective precipitation, designated SP-GA, may have a purity ranging from about 40% to about 75%, or from about 45% to about 75%, or from about 50% to about 75%, or from about 55% to about 75%, or from about 60% to about 75%, or from about 65% to about 75% or from about 70% to about 75%.

[0031] In one or more aspects, the SP-GA may be used without further processing. In some aspects, the selective precipitation process can be used one or more additional times to further purify the SP-GA. In other aspects, the SP-GA may be subjected to reactive crystallization. In still other aspects, sodium gluconate remaining in solution after pH adjustment can be further treated to meet one or more user and / or process needs.

[0032] In one or more aspects, a method of the present disclosure comprises reactive crystallization of a composition comprising glucaric acid. The composition comprisingglucaric acid may be the product recovered from a chemoenzymatic oxidation of glucose as described herein and comprises both glucaric acid and gluconic acid. In other aspects, the composition comprising glucaric acid is an SP-GA.

[0033] Herein, reactive crystallization refers to those processes in which a chemical reaction produces a specific crystallizable species in solution and, thereby, generates a driving force for the formation of a crystalline product. Reactive crystallization may be characterized by features such as (1 ) being controlled by equilibrium alterations where removal of the reaction product from solution by crystallization pulls the reaction towards the product as dictated by Le Chatelier's principle and (2) if the desired product is an intermediate in a larger reaction network, the yield of that product is reduced by its subsequent reaction. Thus, the yield of the target product can be increased by operating under conditions that result in reactive crystallization of the target product. A driving force for reactive crystallization can be created or enhanced by external adjustments such as solvent removal (for example, by evaporation or transport through a membrane), adjustment of pH, change in temperature, addition of a nonsolvent or combinations thereof. In reactive crystallization, system conditions usually are selected so that reactants and byproducts remain in solution, and the driving force for crystallization of the reaction product is created by its synthesis.

[0034] In one or more aspects of the present disclosure, the reactive crystallization conditions may comprise a change in the temperature, pH, or concentrations of materials to produce target compounds having an increased particle size.

[0035] The glucaric acid particles of the present disclosure may be characterized by particle sizes ranging from about 0.1 micons (pm) to about 700 pm, or about 1 pm to about 650 pm, or about 10 pm to about 500 pm, alternatively from about 50 pm to about 300 pm or alternatively from about 100 pm to about 300 pm. The glucaric acid may be further characterized by a particle size distribution percentile where D10 is from about 5 pm to about 10 pm, a D50 of from about 20 pm to about 40 pm and a D90 of from about 100 pm to about 150 pm. It is contemplated that the increased particle size of the target compound (i.e., glucaric acid) will facilitate filtering and drying the solids easier upon scaleup. The crystallized glucaric acid may be dried.

[0036] A centrifuge may be employed to dry the glucaric acid crystals which may be advantageous on scale up compared to the lab scale crystal drying. Because of the crystallization kinetics, glucaric acid crystals crash out of the mother liquor, and the mother liquor may be recycled back into the process (e.g., crystallizer). Glucaric acidobtained by reactive crystallization, designated RC-GA, may have a purity ranging from about 40% to equal to or greater than about 99%, or from about 45% to about 95%, or from about 50% to about 90%, or from about 55% to about 90%, or from about 60% to about 90%, or from about 65% to about 90% or from about 70% to about 90%, or from about 75% to about 90% or from about 80% to about 90% or from about 85% to about 90%.

[0037] The products of the chemoenzymatic oxidation of glucose may be purified using one or more of the methodologies disclosed herein. With reference to Figure 1 , an exemplary system for the production of high purity glucarate 100 is depicted. With reference to Figure 1 , reactants (water 10, glucose 10, an oxidative enzyme 10, and air 10) may be introduced to an enzyme oxidation reactor 110 under conditions suitable for the oxidation of glucose. In an aspect, products of the reaction, glucodialdose (GDA) and water may be conveyed to a reactor containing a transition-metal catalyst (MOR) 120. In the MOR, GDA in the presence of air and an oxidizing transition-metal catalyst may be further oxidized to form a product mixture comprising glucaric acid and gluconic acid. The product mixture may be conveyed to a crystallizer 130 to which acids such as nitric acid and bases such as potassium hydroxide may be introduced. Potassium glucarate crystals may be formed in the crystallized 130 which can be conveyed to a solid liquid separator 140. In some aspects, at least a portion of the potassium gluconate and glucarate remaining in solution may be reintroduced to the MOR 120 and subjected to additional oxidation and crystallization. In one or more aspects, the potassium glucarate crystals are separated into a mother liquor and dry potassium glucarate crystals. The dry potassium glucarate crystals may be used without further processing. In other aspects, the dry potassium glucarate crystals are further processed such as by concentration and / or filtration.

[0038] In one or more aspects, a chemoenzymatic method for generation and purification of glucose oxidation products is depicted in Figure 2. With reference to Figure 2, reactants (air 210, water 210, glucose 210, sodium phosphate 210, and an oxidative enzyme catalyst 210) are conveyed to an enzyme reactor 220 such as a sparging column. The reactants in the enzyme reactor 220 may be subjected to conditions suitable for the formation of one or more glucose oxidation products. The one or more glucose oxidation products may then be subjected to filtration through a molecular weight cutoff membrane (MWCO) 230 resulting in a filtered mixture lackinglarge molecular weight components such as the enzyme. In some aspects, enzyme recovered from the MWCO is recycled back to the enzyme reactor 220.

[0039] The filtered mixture may then be conveyed to an ion exchange column (IX) 240 where the cations in the filtered mixture are exchanged to form an exchanged filtered mixture which can then be conveyed to a metal oxidation reactor 250. Disposed within the metal oxidation reactor 250 may be one or more transition-metal catalysts which are contacted with the exchanged filtered mixture under conditions suitable for further oxidation to form a first product mixture. The first product mixture may comprise gluconic acid and glucaric acid. In another aspect, the first product mixture is conveyed to a mechanical vapor recompression (MVR) unit 260. MVR is an evaporative concentration technology. Subsequent to MVR 260, the first product mixture forms a treated mixture which may then be conveyed to a crystallizer 270. In the crystallizer 270, potassium hydroxide can be added to the treated mixture and the contents subjected to condition suitable for reactive crystallization and the formation of a potassium gluconate slurry, liquid potassium gluconate and solid potassium glucarate.

[0040] In one or more aspects, a chemoenzymatic method for generation and purification of glucose oxidation products is depicted in Figure 3. With reference to Figure 3, reactants (air 310, water 310, glucose 310, potassium hydroxide 210, and an oxidative enzyme catalyst 210) are conveyed to an enzyme reactor 320 such as a sparging column. The reactants in the enzyme reactor 320 may be subjected to conditions suitable for the formation of one or more glucose oxidation products. The one or more glucose oxidation products may then be filtered through a molecularweight cutoff membrane 330 resulting in a filtered mixture lacking large molecular weight components such as the enzyme catalyst. The filtered mixture may then be conveyed to a metal oxidation reactor 340 where it is contacted with a transition-metal catalyst, air 310, and potassium hydroxide and subjected to oxidation conditions to produce a first product mixture. The first product mixture comprising potassium glucarate and potassium gluconate may be introduced to a crystallizer 370 where a second product mixture comprising potassium glucarate slurry, liquid potassium gluconate and solid potassium gluconate is formed. In one or more aspects, at least a portion of the solid potassium gluconate and at least a portion of the liquid potassium glucarate from the second product mixture is introduced to an IX 360 where the potassium salt in the compound is exchanged for a proton. The liquid glucaric acid product of the IX 360 may be conveyed to a MVR 350 for concentration of the glucaric acid.

[0041] In one or more aspects, glucaric acid may be purified from a mixture of gluconic acid and glucaric acid, designated GOGA. This is depicted schematically in Figure 4. With respect to Figure 4, a system for purification of glucaric acid from GOGA 400 comprises introducing GOGA 410 and potassium hydroxide (KOH) 420 to a suitable mixer 430. In one or more aspects, the mixer 430 is operated under conditions suitable for production of potassium glucarate which is an insoluble salt under the mixing conditions. In on or more aspects, at least a portion of the potassium glucarate solid formed in the mixer 430 is conveyed to an IX 460 to replace the potassium cation with a proton and form a glucaric acid composition. The glucaric acid composition may be conveyed from the IX 560 to a concentrator 450 which enriches the glucaric acid concentration to equal to or greater than about 50%. Concentrated glucaric acid may be conveyed through a filter 440 which specifically decreases the amount of solid glucaric acid lactones present in the concentrator and further purifies the concentrated glucaric acid.

[0042] In one or more aspects, a product mixture containing glucaric acid and gluconic acid may be used to generate the potassium salt, calcium salt or purified free acid. This process is depicted schematically in Figure 5 where a system for this process 500, is outlined. With regard to Figure 5, two sets of reactants, each component designated 510 are depicted. In one or more aspects, a GOGA and KOH are introduced to a mixer 520 which is operated under conditions suitable for the formation of soluble potassium gluconate and solid potassium glucarate. At least a portion of the solid potassium glucarate may be conveyed to a second mixer 530 along with calcium chloride (CaCI2) and subject to conditions suitable for the formation of a calcium glucarate solid. At least a portion of the calcium glucarate solid may conveyed to a third mixer 540 where it is contacted with sulfuric acid, H2SO4, under conditions suitable for the formation of a calcium sulfate solid, CaSO4, and glucaric acid liquid. At least a portion of the glucaric acid liquid is then conveyed to a concentrator 560 where the glucaric acid concentration is increased before at least a portion is conveyed to a filter 550. At the filter 550 some solid glucaric acid lactones may be removed from the glucaric acid composition.

[0043] The compositions and methods of the present disclosure will generate glucaric acid at high purity. In an aspect of the present disclosure, glucaric acid may be purified from mixtures comprising glucaric acid and gluconic acid by reactive crystallization, selective precipitation or combinations thereof.ADDITIONAL DISCLOSURE

[0044] A first aspect which is a method of preparing high purity glucaric acid comprising introducing a mixture comprising glucaric acid and one or more sugar oxidation products to a reactive crystallization unit under conditions suitable for formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.

[0045] A second aspect which is the method of the first aspect wherein the one or more sugar oxidation products comprise gluconic acid.

[0046] A third aspect which is the method of any of the first through second aspects wherein the mixture comprising glucaric acid is sourced from a sugar.

[0047] A fourth aspect which is the method of any of the first through third aspects wherein conditions suitable for the formation of an insoluble salt of glucaric acid comprise contacting the mixture comprising glucaric acid with a potassium salt.

[0048] A fifth aspect which is the method of the fourth aspect wherein the potassium salt comprises potassium chloride, potassium acetate, potassium hydroxide, potassium iodide, potassium bicarbonate, potassium carbonate or combinations thereof.

[0049] A sixth aspect which is the method of the fourth aspect wherein the potassium salt comprises potassium hydroxide.

[0050] A seventh aspect which is the method of the fourth aspect wherein the potassium salt is present in an amount ranging from about 2 wt.% to about 60 wt.% based on the total weight of the mixture comprising glucaric acid and potassium salt.

[0051] An eighth aspect which is the method of any of the first through seventh aspects wherein the insoluble salt of glucaric acid has a purity ranging from about 40% to about 75%.

[0052] A ninth aspect which is the method of any of the first through eighth aspects further comprising contacting the insoluble salt of glucaric acid with an ion exchange column under conditions suitable for production of glucaric acid.

[0053] A tenth aspect which is the method of the ninth aspect wherein the glucaric acid has a purity of from equal to or greater than about 75% to about 99%.

[0054] An eleventh aspect which is a method of preparing high purity glucaric acid, comprising introducing glucose to a reactor system comprising at least one oxidation reactor and at least one crystallization unit wherein the glucose when disposed in the oxidation reactor is subjected to conditions suitable for the formation of one or more glucose oxidation products and wherein the one or more glucose oxidation products when disposed in the crystallization unit is subjected to conditions suitable for theformation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.

[0055] A twelfth aspect which is the method of the eleventh aspect wherein at least one oxidation reactor is an enzyme oxidation reactor.

[0056] A thirteenth aspect which is the method of the twelfth aspect wherein disposed within the enzyme oxidation reactor is an oxidase.

[0057] A fourteenth aspect which is the method of any of the eleventh through thirteenth aspects wherein at least one oxidation reactor is a metal oxidation reactor.

[0058] A fifteenth aspect which is the method of the fourteenth aspect wherein disposed within the enzyme oxidation reactor is a transition-metal catalyst.

[0059] A sixteenth aspect which is the method of any of the eleventh through fifteenth aspects wherein the one or more glucose oxidation products comprise gluconic acid and glucaric acid.

[0060] A seventeenth aspect which is the method of the sixteenth aspect wherein an insoluble salt of glucaric acid is formed in the crystallizer.

[0061] An eighteenth aspect which is the method of the seventeenth aspect wherein the insoluble salt is a potassium salt.

[0062] A nineteenth aspect which is the method of the eighteenth aspect wherein the potassium salt comprises potassium chloride, potassium acetate, potassium hydroxide, potassium iodide, potassium bicarbonate, potassium carbonate or combinations thereof.

[0063] A twentieth aspect which is the method of any of the eleventh through nineteenth aspects wherein the insoluble salt of glucaric acid has a purity of from about 40% to about 75%.EXAMPLES

[0064] The presently disclosed subject matter having been generally described, the following examples are given as particular aspects of the subject matter and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims in any manner.EXAMPLE 1

[0065] Reactive crystallization as a method for the purification of glucaric acid was investigated.

[0066] Gluconic acid 50% and glucaric acid 50% (50 grams each), GOGA, were combined and a molar amount of solid KOH added to generate a product mixture. The product mixture was then introduced to an ice bath to accelerate potential crystallization. Upon crystallization, the solids were collected after being filtered and washed with water using a vacuum flask and 0.45 micron filter. HPLC analysis was carried out on the GOGA prior to addition of KOH, and the solid residue after KOH addition. The specific amounts of acid present in each sample (grams of gluconic, glucaric, and KOH) is outlined in Table 1 .Table 1

[0067] With reference to Table 1 , GOGA is a mixture of gluconic acid and glucaric acid in the ratio indicated where GA refers to glucaric acid and GO refers to gluconic acid. Upon addition of the KOH, a solid precipitant was observed to crash out of the solution. To determine if the precipitant was purified glucaric acid, an Ultra High Pressure Liquid Chromatography, coupled with a Mass Spectrometry analysis, HPLC-MS, was conducted. The results are presented in Table 2.Table 2

[0068] As seen in Table 2, the GOGA mixture (before KOH addition) contained approximately 20% gluconic acid and approximately 14% glucaric acid. The KOH generated precipitate was found to contain a dramatically reduced amount of gluconic acid, decreasing from approximately 20% to less than 1 % while the glucaric acid remained around 14%.

[0069] The exact concentrations of gluconic acid and glucaric acid were then determined by generating a calibration curve from known high purity compounds. Samples having a known concentration of either acid was used as a control. The calibration curve was created by precisely measuring GO and GA on an analyticalbalance. A 1000 ppm stock solution that contained both GO and GA was created. The stock solution was diluted into the concentrations analyzed by HPLC-MS. The calibration curve had 6 unique points, which were 25 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, and 500 ppm. When comparing the six points they had an R2value of greater than 0.99 and the calibration curve was considered valid. Samples were prepared in a manner that allowed them to have a concentration between the lowest point and the highest point on the calibration curve.

[0070] The samples were prepared in the following way for analysis. With samples that have a total concentration greater than 25% (e.g., the GOGA sample tested), the sample was diluted using 4 different dilution factors (DF). These DFs are 50, 100, 1000, and 2000 and run in triplicates.

[0071] These different samples were made as follows: using a calibrated pipette, 20 pL of sample was aliquoted in the first 3 spots and 10 pL of sample in spots 4, 5, and 6. To these spots was added 980 pL of basic HPLC water to the first the 3 spots and 990 pL of Basic HPLC water to spots 4, 5, and 6, where basic HPLC water was a pH 10 solution of ammonium hydroxide in demineralized water. Then 100 pL of spot 4, 5, and 6 were pipetted to spots 7, 8, and 9. Subsequently 50 pL of spots 4, 5, and 6 were pipetted to spots 10, 11 , and 12 before 900 pL of basic HPLC water was added into spots 7, 8, and 9. Basic HPLC water, 950 pL, was added into spots 10, 11 , and 12. Table 3 is a summary of the samples.Table 3

[0072] Control samples were prepared in a similar manner. Using the stock solution, the samples were diluted to following concentrations. 50, 150, and 300 ppm. All the standards, unknown, and calibration samples are run using the following HPLC-MS method conditions: Column: Waters Torus 2-PIC (130A, 1.7um 2.1 x 50 mm), Compounds: retention times and QDa detection MS-Channels, Injection volume: 1 pL, Mobile Phase A: 50 mM ammonium formate 0.9% formic acid in H2O, Mobile Phase B:0.9% formic acid in acetonitrile, Flow rate: 0.6 mL / min, Column temperature: 50°C,Detector: QDa and Run time: 2.70 minutesGradient:Table 4

[0073] The concentration of gluconic acid and glucaric acid in the samples was quantified and confirmed by HPLC spectral analysis, Figures 2 and 3. The HPLC scans also confirmed the quantitative results. As seen in the Figure 2 the mixture prior to the addition of KOH has multiple components in the stream. Subsequent to the addition of KOH, Figure 3, the gluconic acid peak at 0.642 minutes was significantly reduced. Furthermore, other peaks that were present prior to KOH addition were reduced significantly.EXAMPLE 2Experiment: KGA Crystallization in 1 L Benchtop Crystallizer

[0074] Results from pure component solubility tests that were performed for KGA and KGO at various temperatures and pH values are shown in Tables 5 and 6. The feedstock used was a GOGA produced chemoenzymatically using a pilot plant MOR. HPLC results indicated initial concentrations of 4.62 wt.% GA, 3.71 wt.% GO. Equations 1-5 were used to calculate and ensure the final GO wt.% in the mother liquor after crystallization was below 85% of the optimum GO wt.%.

[0075] 3D surface plots of the saturation concentrations as a function of temperature and pH were constructed for KGA, Figure 8A; KGO, Figure 8B and a mixture of KGOand KGA, Figure 80. The plot of KGO / KGA solubility finds the optimum point that will maximize KGO’s solubility.

[0076] The plot of KGO / KGA solubility found the optimum point that will maximize KGO’s solubility in solution while minimizing KGA’s solubility during crystallization. Optimum crystallization parameters are presented in Table 7 for KGA and KGO.Table 5Table 6Table 7

[0077] A series of crystallization experiments were run in a 1 L benchtop crystallizer. The feedstock used was a 10wt% solution of gluconic acid, glucaric acid, and other oxidation products produced in the pilot plant metal oxidation reactor (MOR). HPLC results indicated initial concentrations of 4.62 wt.% GA, 3.71 wt.% GO. Equations 1-5 calculated the final GOGA concentration that ensured the final GO wt.% in the mother liquor after crystallization is below 85% of the optimum GO wt.%.

[0078] KOH was added in 10% excess to the concentrated GOGA, and the solution mixed for 30 mins before cooling to 5 °C. Nitric acid (25%(v / v)) was used to titrate the solution down to pH of 4.02. The resulting sample masses are presented in Table 8.Table 8Nitric Acid Added 41.59

[0079] Crystals quickly crashed out of solution after titrating the solution with nitric acid, and the mixture was agitated overnight The solids came out of the crystallizer as a slurry with the mother liquor, and they were separated by vacuum filtration before being freeze dried in a lyophilizer. The final purity of the crystals that crashed out was 87 wt.% KGA, 5 wt.% KGO, and 8 wt.% other impurities. After accounting for an 8% loss of material after filtering and drying, 47 mol% of the glucaric acid in the original acid free GOGA solution was crystallized and recovered as KGA.EXAMPLE 3Process: Producing a purified liquid glucarate stream.

[0080] A concentrated liquid mixture of gluconic and glucaric acid was introduced to a crystallization unit. The system 100 was described in Figure 1 . Notably, the system can be disposed downstream of a concentrated GOGA production process

[0081] The purification process may be further expanded to include an ion exchange unit which may be used downstream of crystallization. This process is depicted in Figure 2. The resulting product was a purified liquid glucaric acid stream. With the MVR, this stream can be concentrated to an application target specification.

[0082] While aspects of the presently disclosed subject matter have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the subject matter. The aspects described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the subject matter disclosed herein are possible and are within the scope of the disclosed subject matter. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.). Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc.

[0083] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an aspect of the present disclosure. Thus, the claims are a further description and are an addition to the aspects of the presently disclosed subject matter. The discussion of a reference herein is not an admission that it is prior art to the presently disclosed subject matter, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein.

Claims

CLAIMSWhat is claimed is:1 . A method of preparing high purity glucaric acid comprising: introducing a mixture comprising glucaric acid and one or more sugar oxidation products to a reactive crystallization unit under conditions suitable for formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.

2. The method of claim 1 , wherein the one or more sugar oxidation products comprise gluconic acid.

3. The method of claim 1 , wherein the mixture comprising glucaric acid is sourced from a sugar.

4. The method of claim 1 , wherein conditions suitable for the formation of an insoluble salt of glucaric acid comprise contacting the mixture comprising glucaric acid with a potassium salt.

5. The method of claim 4, wherein the potassium salt comprises potassium chloride, potassium acetate, potassium hydroxide, potassium iodide, potassium bicarbonate, potassium carbonate or combinations thereof.

6. The method of claim 4, wherein the potassium salt comprises potassium hydroxide.

7. The method of claim 4, wherein the potassium salt is present in an amount ranging from about 2 wt.% to about 60 wt.% based on the total weight of the mixture comprising glucaric acid and potassium salt.

8. The method of claim 1 , wherein the insoluble salt of glucaric acid has a purity ranging from about 40% to about 75%.

9. The method of claim 1 , further comprising contacting the insoluble salt of glucaric acid with an ion exchange column under conditions suitable for production of glucaric acid.

10. The method of claim 9, wherein the glucaric acid has a purity of from equal to or greater than about 75% to about 99%.

11. A method of preparing high purity glucaric acid, comprising: introducing glucose to a reactor system comprising at least one oxidation reactor and at least one crystallization unit wherein the glucose when disposed in the oxidation reactor is subjected to conditions suitable for the formation of one or more glucose oxidation products and wherein the one or more glucose oxidation products when disposed in the crystallization unit is subjected to conditions suitable for the formation of an insoluble salt of glucaric acid; and recovering the insoluble salt of glucaric acid.

12. The method of claim 11 , wherein at least one oxidation reactor is an enzyme oxidation reactor.

13. The method of claim 12, wherein disposed within the enzyme oxidation reactor is an oxidase.

14. The method of claim 11 , wherein at least one oxidation reactor is a metal oxidation reactor.

15. The method of claim 14, wherein disposed within the enzyme oxidation reactor is a transition-metal catalyst.

16. The method of claim 11 , wherein the one or more glucose oxidation products comprise gluconic acid and glucaric acid.

17. The method of claim 16, an insoluble salt of glucaric acid is formed in the crystallizer.

18. The method of claim 17, wherein the insoluble salt is a potassium salt.

19. The method of claim 18, wherein the potassium salt comprises potassium chloride, potassium acetate, potassium hydroxide, potassium iodide, potassium bicarbonate, potassium carbonate or combinations thereof.

20. The method of claim 11 , wherein the insoluble salt of glucaric acid has a purity of from about 40% to about 75%.

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