SU1467050A1 - Method of extracting c1-c5-alkylhydroxamic acids - Google Patents

Abstract

The invention relates to hydroxylamino compounds, in particular to the isolation of (C, -Cj) alkylhydroxamic acids (obtained by reacting the carboxylic acid intermediate ester with a hydroxylamine salt), which are used in analytical chemistry, color photography, polymer production, and biologically active compounds. The goal is to increase product yield and simplify the process. Ethylenediaminetetraacetic acid is introduced into the reaction mass at a molar ratio of alkyl hydroxamic acid: EDTA 1: 0.5-2.0, followed by evaporation to dryness and extraction of the product with ethanol. 1 tab. sh (l

Description

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The invention relates to an improved method for the isolation of (C, -Sy) - alkylhydroxamic acids which are used in analytical chemistry, color photography, the production of polymers, biologically active compounds.

The purpose of the invention is to increase the product yield and simplify the process.

The goal is achieved by treating the reaction mass with ethylenediaminetetraacetic acid (EDTA) at a molar ratio of alkylhydroxamic acid: EDTA 1: 0.5-2.0, followed by evaporation of the reaction mass to dryness and extraction of the product.

With the introduction of EDTA into the reaction mass, part of it is spent on neutralizing the excess of silk, and the other part goes on the release of hydroxamic acid in free form. When choosing the ratio between hydroxamic acid and EDTA, the best results are obtained at a molar ratio of 1: 0.5-2.0, respectively. When the amount of EDTA is less than 0.5 mol, the degree of hydroxamic acid recovery falls. If EDTA is taken to be more than 2.0 mol, then a decrease in the yield of the target product is also observed, apparently y, due to the noticeable adsorption of hydroxamic acids on EDTA.

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After adding E-DTA, the reaction mass having a pasty appearance is evaporated at 50-60 ° C. At a higher temperature, hydroxamic acids can be melted. Forming with a dense mass dries longer. The drying process is favored by the vacuum, since the drying time

under vacuum get 20.8 g of acetohydroxamic acid, that. is 92.6%, based on the starting ester.

 Example 2. The reaction mass obtained by the interaction of the ester of acetic acid with hydroxylamine hydrochloride chloride according to example 1 and containing

this is reduced. Drying required 15.01 g (0.2 M) mA to remove water from the reaction mass in which EDTA and its salts are poorly soluble.

From the dry residue, hydroxamic acid is extracted with organic solvents 15 that do not dissolve EDTA and its salts.

It is preferable to use ethyl alcohol and ethyl acids for this purpose, pour 500 cm and add ethylenediaminetetrauk. Mixture of thoroughly peated paste up to 60 ° C.

To the dry residue of ethyl alcohol and the mixture is filtered black. Alcohol solution is given free gita. Alcohol-distilled to extract the acid. Operation n

acetate, acetone, as they are well soluble in lower alkyl hydroxamic acids. These solvents are light boiling, so the evaporation is carried out under mild conditions.

For the synthesis, methyl, ethyl and propyl esters of carboxylic acids p and hydroxylamine hydrochloric acid or sulfate, sodium or potassium hydroxide are used. Molar

The ester: hydrochloric 30 ratio is floated. When stored in a desiccator

hydroxylamine: sodium (potassium) hydrate, respectively 1: 1.0-1.35: 2.0-2.5. In the case of use, hydroxylamine sulfate, it is taken from the calculation of 0.5-0.7 mol per 1 mol of ester. The process is carried out with stirring in the temperature range.

0-60 ° C.

Example 1. B three-neck flask equipped with a stirrer, a thermometer,

reflux condenser and water bath, placed 24 cm methyl ester

of acetic acid and 22.9 g of hydroxylamine hydrochloride dissolved in 53.5 cm of water. The mixture is stirred for 5 minutes, and then a solution of 25.6 g of sodium hydroxide is carefully poured into 39 cm of water. The process is carried out for 1 h at 40 C and vigorous stirring. After completion of the synthesis, the reaction mass is poured into a glass, and then, with stirring, 87.7 g of ethylenediaminetetraacetic acid are poured into it. The resulting paste is placed in a porcelain dish and dried in a drying oven to constant weight. Hydroxamic acid is extracted from the dry mass with ethyl alcohol. By evaporation ekst

schuyu 15.01 g (0.2 M)

hydra oxamic

acid, poured into cTakaH with a capacity of 500 cm and 5.85 g (0.2 M) of ethylenediaminetetraacetic acid added. The mixture is thoroughly mixed. The resulting paste is evaporated at 50-60 ° C to a constant weight.

200 cm of ethanol are added to the dry residue and mixed. The mixture is filtered through a Büchner funnel. The alcohol solution is evaporated and the free hydroxamic acid is yo-yized. The distillate alcohol is again used to extract hydroxamic acid. The operation is repeated three times.

13.92 g of acetohydroxamic acid are obtained by isolation; yield 93.3%, T.Sh1. 78 sec.

The resulting acid is very hygroscopic, in air with time {"ac35

40

melting point increases to 83-84 C.

Found,%: C 32.63; H 6.80; N 19.01.

Calculated,%: C 32.00; H 6.71; N 18.66. .

Examples of the preparation of hydroxamic acids according to the method described in Examples 1 and 2 are tabulated.

The use of EDTA makes it possible to reject the use of mineral acids, which cause acid-catalysis decomposition of the target product, and contributes to an increase in its p: final yield.

Refusal to use hydrogen sulfide in the proposed method allows to improve the sanitary and hygienic conditions for the work on the synthesis of lower alkyl hydroxamic acids.

Ethylenediaminetetraacetic acid can be used repeatedly, since the formed sodium and carbonate salts of EDTA are easily converted into free EDTA by acidification with mineral acids. The mechanical loss of EDTA during the release of hydroxamic acids is negligible.

Claims (1)

Invention Formula The method of separation of C-Su-alkylhydroxamic acids obtained by the interaction of carboxylic acid ester with a hydroxylamine salt, including evaporation of the reaction mass to dryness and extraction of the product Note. To isolate the valerihydroxam acid was used ethyl acetate, in all other cases ethanol. ethanol, characterized in that, in order to increase the yield of the product and simplify the process, ethylenediamine-cyclic acid is introduced into the reaction mass at a molar ratio of alkyl hydroxamic acid: EDTA 1: 0.5-2.0.