RU2072348C1 - Process for preparing aqueous solution or glyoxylic acid - Google Patents

Abstract

FIELD: synthesis of medicinal and cosmetic agents. SUBSTANCE: product glyoxylic acid: C₂H₂O₃.. Yield is 10-70%. Reagent 1: oxygen containing compounds of formula: X-CH₂OH, wherein X is CN or COOH. Reagent 2: nitric acid. Reaction conditions: oxidation of these compounds in hydrochloric acid having 27-37% concentration in the presence of vanadium pentaxide in amount of 0.002-0.01 per mole of organic compound at 20-70 C. EFFECT: more efficient preparation process. 2 cl, 2 tbl

Description

 The invention relates to chemical technology for the production of glyoxyl acid CHO-COOH, used for the synthesis of pharmaceutical and cosmetic preparations.

Known methods for producing glyoxylic acid by oxidation of glyoxal with nitric acid [1-3]
The disadvantage of these methods is the use of inaccessible glyoxal feedstock, as well as the complexity of the process [1,2]
The aim of the proposed invention is to reduce raw materials costs and expand the raw material base for glyoxylic acid production, as well as simplifying the process.

This goal is achieved in that glyoxylic acid is obtained by nitric acid oxidation of compounds of the type X-CH ₂ OH, where X-CN, -COOH at a temperature of 20-70 ^o C in the presence of a catalyst of vanadium pentoxide, in hydrochloric acid with the yield of the target product from 10 up to 76% of theoretically possible. The advantage of the method is that methylenecyanohydrin HOCH ₂ CN, which is obtained by known methods from the products of oxidative ammanolysis of natural gas and methane, is used as a feedstock.

Выходы метиленциангидрина (МЦГ) и гликолевой кислоты количественные. Предлагаемый метод позволяет получать глиоксиловую кислоту из простейшего сырья: аммиака и природного газа, что делает способ легко осуществимым в промышленности.

The yields of methylene cyanohydrin (MCH) and glycolic acid are quantitative. The proposed method allows to obtain glyoxylic acid from the simplest raw materials: ammonia and natural gas, which makes the method easily feasible in industry.

 The method of obtaining glyoxylic acid is given in the examples.

 The influence of the parameters of the process of nitric acid oxidation of glycolic acid in a hydrochloric acid medium is presented in table. one.

The maximum yield of glyoxylic acid 73-76% of theoretically possible is ensured by the addition of 0.002-0.01 ppm. catalyst per 1 ppm glycolic acid. Deviation from this interval leads to a decrease in the yield of the final product, and in the absence of a catalyst, glyoxylic acid is not formed. Oxidation of glycolic acid is carried out with concentrated nitric acid, taken in an amount of 0.8-2.0 ppm. preferably 1.0 ppm at 1 ppm oxidizable compounds within 10-210 minutes The medium used is hydrochloric acid with a concentration of 29-37%. The content of the oxidizable compound in hydrochloric acid is 0.8-6.6 wt. The regularities of glyoxylic acid formation during the oxidation of MCH (methylene cyanohydrin) in hydrochloric acid and in the presence of a V ₂ O ₅ catalyst are similar to the regularities of glyoxylic acid formation during glycolic acid oxidation, however, the yield of the final product is lower and reaches a maximum of 48% of the theoretically possible. The results are presented in table. 2.

 As a result of the oxidation of oxygen-containing compounds, glyoxylic acid is obtained in the form of an aqueous solution with a wide range of concentration of 5-50%, which does not significantly affect the quality of the final product.

 Example 1

5 g of glycolic acid is sprinkled with stirring at a temperature of 20 ^o C in 100 ml of 36% hydrochloric acid. 2.8 ml of concentrated nitric acid are poured into the resulting solution, and 0.025 g of vanadium pentoxide is added. The resulting solution was kept under stirring at a temperature of 20 ^o C for 210 minutes. After exposure, analyze the content of glyoxylic acid in solution by UV spectroscopy. (The analysis procedure is given below). 3.65 g of glyoxylic acid was found in the solution (yield 74.9% of theoretically possible). Hydrochloric acid is distilled off from the resulting solution at atmospheric pressure to a residual mass of 10 g and re-analyzed for glyoxylic acid content. Obtain 10.0 g of an aqueous solution containing 3.65 g of glyoxylic acid (yield 74.9% of theoretically possible).

 Example 4

5 g of glycolic acid is sprinkled with stirring at a temperature of 20 ^o C to 100 ml of 36% hydrochloric acid. 2.8 ml of concentrated nitric acid are added to the solution and 0.025 g of vanadium pentoxide is added. The solution is heated to 50 ^o C and maintained at this temperature for 14 minutes. Cool the solution to 20 ^o C and analyze the content of glyoxylic acid by UV spectroscopy.

 3.66 glyoxylic acid was found in the solution, hydrochloric acid was distilled off to a residual mass of 7.0 g at atmospheric pressure. Re-analyze the content of glyoxylic acid. Obtain 7.0 g of an aqueous solution containing 3.66 g of glyoxylic acid (yield 75.1% of theoretically possible).

 Example 7

 Analogously to example 4, except for using 2.25 ml of nitric acid. Obtain 5.0 g of an aqueous solution containing 2.43 g of glyoxylic acid (yield 49.9% of theoretically possible).

 Example 8

 Analogously to example 4, except for using 5.6 ml of nitric acid. Get 7.0 g of an aqueous solution containing 3.59 g of glyoxylic acid (yield 73.8% of theoretically possible).

 Example 10

 Analogously to example 4, with the exception of 0.125 g of vanadium pentoxide. Get 10 g of an aqueous solution containing 3.65 g of glyoxylic acid (yield 75.0% of theoretically possible).

 Example 15

 Analogously to example 4, with the exception of 65.0 ml of 36% hydrochloric acid was used and held for 10 minutes. Get 7.0 g of an aqueous solution containing 2.87 g of glyoxylic acid (yield 58.9% of theoretically possible).

 Example 17

 Analogously to example 4, with the exception of using 100 ml of 30.8% hydrochloric acid and incubated for 35 minutes. Get 7.0 g of an aqueous solution containing 2.58 g of glyoxylic acid (yield 53.1% of theoretically possible).

 Example 20

5.7 g of methylene glyanohydrin are metered out to 100 ml of 36% hydrochloric acid at a temperature of 20 ^° C. 4.2 ml of concentrated nitric acid are poured into the resulting solution and 0.036 g of vanadium pentoxide are added. The solution is heated to 30 ^o C and maintained at this temperature for 90 minutes. Cooled to 20 ^o C and analyze the content of glyoxylic acid by UV spectroscopy. 3.55 g of glyoxylic acid was detected in the solution. Hydrochloric acid is distilled off to a residual mass of 10.0 g at atmospheric pressure. Re-analyze the content of glyoxylic acid. Obtain 10.0 g of an aqueous solution containing 3.55 g of glyoxylic acid (yield 48% of theory).

 Example 21

Analogously to example 20, except that the oxidation is carried out at 50 ^o C for 16 minutes. Obtain 10.0 g of an aqueous solution containing 3.48 g of glyoxylic acid (yield 47% of theoretically possible).

 Example 24

 Analogously to example 20, except that the concentration of hydrochloric acid is 30.2%, the exposure time is 30 minutes. Obtain 7.0 g of an aqueous solution containing 3.5 g of glyoxylic acid (yield 47.3% of theoretically possible).

Glyoxylic acid analysis procedure
The analysis is carried out by UV spectroscopy. It has been established that in an alkaline environment, glyoxylic acid interacts with hydroxylamine to form glyoxylic acid oxime.

Оксим глиоксиловой кислоты образуется с количественным выходом. Оксим глиоксиловой кислоты был выделен и изучены спектры его поглощения в ультрафиолетовой области. В щелочной среде оксим глиоксиловой кислоты имеет максимум поглощения при λ 251нм, коэффициент молярного поглощения e 7640. На основании изученной зависимости величины оптической плотности при l 251нм от концентрации глиоксиловой кислоты была разработана методика ее анализа в растворах. Проверка этой методики анализом растворов реактивной глиоксиловой кислоты известной концентрации показала хорошую воспроизводимость результатов. Методика обеспечивает определение глиоксиловой кислоты в растворах с погрешностью 2%
Методика анализа была следующей:
Отбирали аликвоту водного раствора, содержащего 0,1.0,3 г глиоксиловой кислоты и переносили ее в мерную колбу на 100 мл и доводили водой до метки. Отбирали 1 мл полученного раствора, помещали в мерную колбу на 100 мл, присыпали в эту колбу 0,1 г NaOH и 0,1 г солянокислого гидроксиламина и доводили объем раствора до 100 мл. Записывали УФ-спектр этого раствора и определяли оптическую плотность при l 251нм.

Glyoxylic acid oxime is formed in quantitative yield. Glyoxylic acid oxime was isolated and its absorption spectra in the ultraviolet region were studied. In an alkaline medium, glyoxylic acid oxime has an absorption maximum at λ 251 nm, the molar absorption coefficient is e 7640. Based on the studied dependence of the optical density at l 251 nm on the concentration of glyoxylic acid, a procedure for its analysis in solutions was developed. Verification of this technique by analysis of known concentration of reactive glyoxylic acid solutions showed good reproducibility of the results. The method provides the determination of glyoxylic acid in solutions with an error of 2%
The analysis procedure was as follows:
An aliquot of an aqueous solution containing 0.1.0.3 g of glyoxylic acid was taken and transferred to a 100 ml volumetric flask and adjusted to the mark with water. 1 ml of the resulting solution was taken, placed in a 100 ml volumetric flask, 0.1 g of NaOH and 0.1 g of hydroxylamine hydrochloride were added to this flask, and the volume of the solution was adjusted to 100 ml. The UV spectrum of this solution was recorded and the optical density was determined at l 251 nm.

 The calibration graph determined the concentration of glyoxylic acid.

 To further control the amount of glyoxylic acid obtained, all solutions obtained after the oxidation of glycolic acid and MCH were used to obtain allantoin.

 Allantoin was prepared according to the following procedure.

аTo 10 g of an aqueous solution containing 3.65 g of glyoxylic acid obtained by oxidation of 5 g of glycolic acid was sprinkled with 10 g of urea and heated to 80 ^° C. 100 ml of water was added to the resulting product and allantoin was filtered off. Received 3.12 g of allontoin with a melting point of 243 ^o C

a

Claims (2)

1. The method of obtaining an aqueous solution of glyoxylic acid by oxidation of an oxygen-containing organic compound at 20 ^{° C.} with concentrated nitric acid in a hydrochloric acid medium, characterized in that a compound of the formula X CH ₂ OH, where X is —CN or —COOH, is used as an oxygen-containing organic compound. while nitric acid is taken in an amount of 0.8 2.0 mol per 1 mol of organic compound, in the presence of 0.002 0.01 mol of vanadium pentoxide per 1.0 mol of organic compound using 29 37% hydrochloric acid at a content oxidized organic compound in hydrochloric acid of 0.8 6.6 wt.  2. The method according to claim 1, characterized in that the nitric acid is taken in an amount of 1.0 mol per 1 mol of organic compound.

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