LV10857B - Method for producing of glucaric acid (saccharic acid) - Google Patents

Abstract

The offered invention refers to a method of obtaining glucuronic acid. The method provides for the catalytic oxidising of glucose in a liquid phase with oxygen or air, which can be used in the pharmaceutical and food industry as well as for manufacturing plastics. Oxidising is done at 60-70 degrees C in chloric acid solution (5-6 mol/l) in the presence of sulfolane or acetic acid anhydride (24-37 percents of volume). Solvent salt of nitrous acid (0.1-0.25 mol/l) shall be used as a catalyst agent.

Description

Method of production of glucaric acid (sugar acid).

The present invention relates to a process for the production of glucaric acid by catalytic oxidation of oxygen with glucose. Glucaric Acid A valuable raw material for the pharmaceutical and food industries as well as for the production of synthetic polymeric materials.

There is a known method for obtaining glucaric acid by oxidizing glucose with concentrated nitric acid at elevated temperature (KIliani H., Ber., 1923, B.56, S.2012; USA Pat.N. 2809989, cl. 260-528, 1957).

The disadvantage of this method is the high amount of ecologically hazardous nitric acid used in the synthesis and the low yield of the final product.

The most analogous method to be applied is - with known glucose oxidation process with air or oxygen in aqueous solutions at pH 5 - 9.6 and temperature 50 C. Platinum (10%) on activated charcoal is used as the catalyst, and the ratio of oxidizable substance to catalyst is 1. : 0.23 · The process is performed with vigorous stirring of the solution for 12.5 hours. The final yield of the product, monopotassium salt of glucaric acid, is 54% (USA Pat. N 2472168, cl. 260-528, 1949).

The disadvantages of this method are, firstly, the expensive use of a catalyst, secondly, the low rate of glucose oxidation, and thirdly the low yield of the product.

The object of the present invention is to intensify and slow down the process and to increase the yield of the product.

The goal is achieved by oxidizing glucose with oxygen to glucaric acid as a catalyser Any water soluble salt of nitric acid is used, except KNO ^, e.g. NaNC ^ (0.1-0.25 mol / l), many times cheaper and more affordable than platinum. The oxidation is carried out with oxygen or air in the presence of hydrochloric acid (HCl 2, 5 ^- 6 mol / l) with an addition of sulfolane or acetic anhydride (24 - 37 vol%) at a temperature of 60 - 70θ0.

It is known that monosaccharides (including glucose) are the most readily oxidizable aldehyde group. Gluconic acid is formed during this type of oxidation. When the glucose molecule also undergoes oxidation of the primary alcohol group to the carboxyl group, glucaric acid is formed.

Oxidation of glucose can be led to gluconic acid by stopping the oxidation process when the oxidizing system has absorbed an amount of oxygen that corresponds directly to the stoichiometry of the reaction with glucose-gluconic acid (per mol of glucose 0.5 mol 0 ^), or by oxidizing in less acidic solutions ( 3-4 mol / L HCl HC).

Glucaric acid can be obtained by continuing oxidation until the system absorbs 1.5 mol per 1 mol glucose.

There is no known method for obtaining glucaric acid by oxidizing glucose in acidic solutions using water-soluble salts of nitric acid in the presence of acetic anhydride or sulfolane.

Example 1. Oxidation is carried out in a thermostated glass reactor mounted on a mechanical shaker. The volume of the reactor is divided by a baffle, which prevents contact between the substrate and the catalyst before the reaction begins. Place one side of the reactor at a concentration of 0.25 mol / l sodium nitrite, the other side glucose 1 mol / l (0.9 g), 6 mol / l hydrochloric acid and 24% v / v sulfolane (based on the total volume of the solution). The total volume of the oxidisable solution is 5 ml. The reactor is connected to a gas burette filled with oxygen. Oxidation is carried out at atmospheric pressure by shaking the reactor at 12 s ^- '' ^- and at a temperature of 70 ° C.

The oxidation process is stopped when the amount of oxygen uptake by the system is consistent with the stoichiometry of glucuric acid formation.

The yield of glucaric acid is determined by gas chromatography, analyzing the products obtained in the form of trimethylsilyl esters. Process selectivity for glucaric acid - 10%, yield - 92%, process duration - 45 min.

The structure of the obtained glucaric acid is confirmed by NMR spectroscopy and elemental analysis.

Glucaric acid is liberated from the reaction solution as a monopotassium salt, yield 74%. (npaKTHKyM no χμμηη yrjieBo.qoB / ĪTo, n, pejl. D.A.EfoaHOBa - 2 Η3β., nepepatf. w nonojiH. - M., BHCin.niKOJia, IS73., c.27.).

Examples 2-9 · Proceed as in Example 1, changing the parameters (see table). The glucose concentration in all examples is 1 mol / l.

The data in the table lead to the conclusion that increasing the temperature as well as increasing the acid concentration accelerates the oxidation process (eg 1,3 and 1,2). Increasing the concentration of the catalyst also contributes to the acceleration of the process (eg 5,6,7), but also has the effect of increasing the amount of sulfolane (eg 3,5). The speed of the process is not affected by the amount of acetic acid (eg 4.9).

The magnitude of the partial pressure of oxygen does not influence the kinetics of the process and the yield of the product, which means that oxidation can occur with both oxygen and air.

Table

No. P · k. Nitric acid salt Volume of food, vol. %% HClO ₄ , conc. mol / l t ° C Branches. time min Glucaric acid comes out. For- mule Conc. mol / l Silicone vinegar. fo- anh. Larry GSH In the form of monopotassium salt 1. NaNO ₂ 0.25 24th 6th 70 45 92 74 2. NaNO ₂ 0.25 35 5 70 70 84 67 3- NaNO ₂ 0.25 24th 6th 60 112 93 74 4. NaNO ₂ 0.25 24th 6th 70 105 89 '70 5- NaNO ₂ 0.25 37 6th 60 73 93 71 6th NaNO ₂ 0.20 37 6th 60 105 92 72 7th NaNO ₂ 0.10 37 6th 60 105 85 67 8th NaNO ₂ 0.25 35 5 60 105 78 60 9th NaNO ₂ 0.25 37 6th 70 105 89 69 10th Mg (NO ₂ ) ₂ 0.15 37 6th 70 105 87 68 11th Zn (NO _£ ) ₂ 0.15 24th 6th 70 52 91 72

Carrying out the oxidation process at temperatures and acid concentrations lower than those stated in the application results in a significant reduction in the process rate as well as the stopping of glucose oxidation at gluconic acid. Organic compounds are destroyed at temperatures and acid concentrations higher than those specified in the application.

Compared to the known method, this method allows the process to be slowed down due to the use of a cheaper and more affordable catalyst: a mixture of nitric acid with HCl 2, sulfolane or acetic anhydride. At the same time, the process speeds up significantly (45 mins to 12.5 hrs) and the product Yield increases (74% versus 54%).

Claims (1)

INVENTION FORMULA The process for the preparation of glucaric acid (sugar) by catalytic oxidation of glucose with air or oxygen in aqueous acidic solutions at elevated temperature is characterized in that the water-soluble salt of nitric acid is used as a catalyst, e.g. sodium nitrite at a concentration of 0,1 to 0,25 mol / l but the oxidation process is carried out in a solution of chloric acid (5 to 6 mol / l) in the presence of sulpholane or acetic anhydride (20-37% v / v) at 6θ to 7ΟθΟ.