SU183740A1 - - Google Patents

Description

The invention relates to the field of producing monoalkyl maleates, which can be used to obtain copolymers, for example alkyl vinyl maleates, dialkyl fumarates.

It is known to prepare monoalkyl maleates by heating the alcohol with maleic anhydride, without purification of the monoalkyl maleate obtained in the course of this.

The proposed method involves the production of a raw pellet product with a reduced content of by-products, as well as purification, due to which the substance corresponds to the acrylate state. Monoalkyl maleate is obtained by pouring a thin stream of alcapol into molten maleic anhydride with heating and stirring. The resulting reaction mass is then purified. To purify the liquid monoalkyl maleate, the reaction mass is neutralized successively with a solution of soda and sodium bicarbonate, the admixture of dialkyl maleate and maleic acid is separated with ether. To isolate monoalkyl maleate, the ether-treated reaction mass is acidified with sulfuric acid to pH 3 and extracted with ether.

The yield of the target product is 55-86%.

Example 1. P o lu and e e it is met m and m and t e. In a three-neck round-bottom flask of 250 ml with a mechanical agitator. a reflux condenser and a thermometer were charged with 62.5 g (0.637% nol) of small anhydride, melted by heating in a water bath and stirred, and then 20 g (0.625 mol) of methanol were poured in a thin stream.

R .. ,, x, l.,.,.

The reaction mixture is heated on water to 60-75 ° C with stirring for 1.5 hours. The reaction product is transferred to a flask and neutralized first with a 20% solution.

5 soda, then saturated sodium bicarbonate solution. The resulting solution of Na-sun monomethyl maleate is treated with three ration of ether, 25 ml each, to extract the dimethyl maleate impurity, and then acidify.

0 20% sulfuric acid to pH 3. Monoalkyl maleate is extracted from this solution by several ether standards. Efnr is distilled off from the ether extract, the residue of monomethyl maleate is dried on a water bath. Output

5 44 g (55o / o).

In the same manner, monoethyl-n-propyl, monoisopropyl maleates and monoallyl maleate are obtained.

r.oro anhydride and 54 ml (0.50 mol) of isoamylosoio alcohol are heated under conditions similar to those of Example 1, raising the reaction temperature to 80 ° C. After acidification by neutralization with a reactive mass, the isoamyl maleate is isolated as an oil. The lower aqueous layer is drained, the monoisoamylate is washed several times with 20 ml of water each time, and then dried in a water bath.

Yield 80 g (86.1%).

Mono-n-butyl-, n-butyl-n-amyl, n-hexyl, nzohexyl, n-octyl and isooctyl maleates are thus obtained.

Example 3. For the sake of his own, and for him, on the subject. 30.6 g (0.312 mol) of maleic anhydride and 48.6 ml (0.307 mol) of decyl alcohol are heated in the same way as described in Example 1. When cooled, the reaction product crystallizes. Purify the monoester by recrystallization from acetone.

The yield of purified moodecyl maleate with a melt temperature of 39-42 ° C is 49.6 g (6f, 8%).

Mono - "- heptyl mono-n-propyl maleates are obtained by the same distillation using i-hexane for recrystallization.

Subject invention

1. A method for preparing pure monoalkyl maleate by heating alcapolone with maleic anhydride, characterized in that, in order to reduce the amount of by-products and

In order to increase the purity of the target products, Alcapol is injected in a thin stream into molten low molecular anhydride with the next purification of the reaction mass.

2. Method of claim 1, characterized in that in order to obtain pure liquid monopoic maleate, the reaction mass is neutralized successively with a solution of soda and saturated sodium bicarbonate solution, treated with ether, acidified with sickle acid to pH 3 and secondarily treated with ether.

3. Method according to paragraphs. 1 and 2, characterized in that, in order to obtain pure solid monoalkyl metal compounds, the reaction mass is recrystallized from acetone.