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Method of Oxidization Using Nitric Acid

a technology of nitric acid and oxidizing method, which is applied in the field of oxidizing method using nitric acid, to achieve the effect of reducing thermal control problems, improving product isolation, and being readily availabl

Inactive Publication Date: 2010-07-29
KIELY DONALD E +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015]An improved method for oxidation of water soluble organic compounds subject to nitric acid oxidation, and particularly carbohydrates of different structures, stereochemistry, and origins, to their corresponding carbohydrate acids, including aldaric acids, addresses issues normally arising in common nitric acid oxidation methodologies. Specifically, the subject method serves to eliminate thermal control issues in the oxidation, the release of oxides of nitrogen into the atmosphere, but provides for removal of post-reaction nitric acid and inorganic compounds, while employing a catalytic process involving use of oxygen to carry out the desired oxidations. As a result, beneficial carbohydrate acids which were previously expensive and burdensome to produce can become relatively cheap and readily obtainable. Furthermore, many aldaric acids that were previously unavailable are now capable of industrial production and commercial development.
[0016]The first step of the subject method is the computer-controlled, catalytic oxidation reaction, wherein nitric acid is put in a closed reactor in contact with various carbohydrate feedstocks under very mild and controlled conditions of oxygen pressure, reaction time, and reaction temperature to allow the oxidation of the carbohydrates to occur. Oxygen consumption in the presence of the aqueous acid solution is associated with nitric acid regeneration from various NOX gases as they are produced in the reaction. Carrying out this step in a controlled manner under relatively low temperature over time avoids the big exotherm normally associated with nitric acid oxidations. The next step in the process is to isolate the oxidized product by removing and recovering the bulk of the nitric acid by distillation, then treating the resulting product with inorganic hydroxide to a basic pH in order to neutralize any residual nitric acid and convert carbohydrate acids into their corresponding acid salts. The resulting aqueous solution, which contains inorganic nitrate and the salt(s) of the product carbohydrate acid(s), is subjected to a filtration leaving the retentate containing the organic acid(s) salt form(s) and the permeate containing the inorganic salts. At this stage, the absence of most of the nitric acid and / or inorganic nitrate from the retentate renders the ease of purification and isolation of the carbohydrate acid non-salt(s) product(s) much improved over previously reported methods. An additional method employed to separate nitric acid from product organic / carbohydrate acids is diffusion dialysis technology. This low energy process is typically employed to separate inorganic acids from metal salts,13, 14 particularly multivalent cation salts, but has not been applied extensively, or at all, to separation of inorganic acids from carbohydrates or carbohydrate acids. The nitric acid recovery stream and organic / carbohydrate acids products streams can be separately processed for nitric acid reuse and organic / carbohydrate acids salts isolation, respectively. Diffusion dialysis separation of nitric acid from organic / carbohydrate acid products offers the additional option of being applied to the oxidation mixture before or after evaporative removal of some portion of the nitric acid, depending upon the advantage that can be utilized on an industrial scale. As with the filtration technology, application of the diffusion dialysis technology ultimately improves product isolation.

Problems solved by technology

Furthermore, many aldaric acids that were previously unavailable are now capable of industrial production and commercial development.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

General Methods

[0031]Solutions were concentrated in vacuo (10-15 mbar) using a rotary evaporator and water bath at 50° C. pH measurements were made with a Thermo Orion 310 pH meter (Thermo Fisher Scientific, Inc., Waltham, Mass., USA) which was calibrated prior to use. Oxidations were carried out in Mettler Toledo Labmax reactor. The Labmax reactor is designed to operate as a computer controlled closed-system reactor. The Labmax was fitted with a top-loading balance, a liquid feed pump, an oxygen Sierra flow valve, a mechanically driven stirring rod, a thermometer, a 1 liter thermal jacketed flask, a FTS recirculating chiller, a pressure manifold fitted with pressure relief valves and pressure gauge and a personal computer with CamileTG v1.2 software. The software installed allows the operator to program experiments based on specific parameters and conditions.

example 2

Nitric Acid Oxidation of D-Glucose

[0032]The aqueous 62.3% D-glucose solution used in the oxidations was prepared by adding solid D-glucose (162.5 g, 0.75 mol) to 97.5 grams of deionized water in a screw-capped flask containing a stir bar. Prior to adding solid D-glucose to the water, the water was heated to ca. 60° C. with stirring. Once the D-glucose was dissolved, the temperature was reduced to ambient and dry sodium nitrite (0.60 g) added to the solution. The total weight of the solution is 260.6 g.

[0033]The Recipe Menu is accessed using the Labmax CamileTG v1.2 software and the reaction parameters for the oxidation were programmed in a series of stages: Stage 1—the reactor temperature was set at 25° C.; the stirring rod speed set at 200 rpm (and held constant throughout all the remaining stages); time set for 1 minute. Stage 2—the reactor temperature was set at 25° C., and the pressure set at 0.25 bar for a duration of 3 minutes. Stage 3—the temperature of the reactor was set at...

example 3

Nitric Acid Oxidation of D-Glucose

[0037]The oxidation of D-glucose was carried out as in Example 1. However, potassium hydroxide was substituted for sodium hydroxide in the neutralization process to give crude D-glucaric acid dipotassium salt (151.25 g, 70.4% based on pure dipotassium D-glucarate). The salt was precipitated from methanol as described to give an off white solid (145.75 g, 67.9% based on pure dipotassium D-glucarate).

[0038]Monopotassium D-glucarate isolation, Method 1. D-Glucose (162.5 g, 0.75 mol) was oxidized using the LabMax reactor and concentrated as described. The concentrate of organic product(s) and residual nitric acid was diluted with deionized water (150 mL) and chilled at 5° C. for 18 h. The pH of the solution was adjusted to a constant pH of 9.1 with 45% KOH (184 mL) in an ice bath and the solution back-titrated to pH 3.4 with concentrated HNO3 (34.6 mL) in an ice bath. A precipitate formed when the solution pH dropped below 5. After cooling the mixture a...

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Abstract

A controlled nitric acid process employing oxygen and nitric acid as co-oxidants is used to oxidize organic compounds subject to nitric acid oxidation, to their corresponding carboxylic acids. Oxidation of some carbohydrates by this process can produce one or more of their corresponding acid forms. The process is carried out at moderate temperatures, typically in the range of 20° C. to 45° C. in a closed reactor, with oxygen gas being introduced into the reaction chamber as needed in order to sustain the reaction. Computer controlled reactors allow for careful and reproducible control of reaction parameters. Nitric acid can be recovered by a distillation / evaporation process, or by diffusion dialysis, the aqueous solution made basic with inorganic hydroxide, and the residual inorganic nitrate removed using a filtration (nanofiltration) device. The method eliminates issues of thermal control of the oxidation, release of nitrogen into the atmosphere, and post-reaction difficulties in the removal of nitric acid and inorganic nitrates.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of co-pending U.S. patent application Ser. No. 11 / 890,760, filed Aug. 6, 2007, which claims the benefits of U.S. Provisional Patent Application No. 60 / 836,329, filed Aug. 7, 2006, the disclosure of which is hereby incorporated by reference in its entirety including all figures, tables and drawings.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with Government support under Grant No. 2001-344463-10521 awarded by the USDA. The Government has certain rights in the invention.REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX[0003]Not applicable.TECHNICAL FIELD[0004]This invention describes a method for synthesizing carbohydrate acids through controlled oxidation of their corresponding carbohydrates using nitric acid and oxygen as the oxidizing agents.BACKGROUND OF THE INVENTION[0005]Carbohydrate acids, and in particular ca...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07D309/30C07C55/02
CPCC07C51/27C07C59/285C07C51/00
Inventor KIELY, DONALD E.HASH, SR., KIRK R.
Owner KIELY DONALD E
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