SU407877A1 - METHOD OF OBTAINING HIGHER 2-ALKENIC ACIDS - Google Patents

Description

one

This invention relates to a new process for the preparation of higher alkene acids, which are widely used in the chemical and polymer industries.

A method of producing alkene acids by condensation of aldehydes with malonic acid at 90-100 ° C in pyridine is known. However, a yield of about 50% of the theoretical is achieved only after 4 days.

In addition, it is known to decarboxylate monocarboxylic acids to olefins using lead tetraacetate (TAC).

In order to simplify the process and increase the yield of higher alkeneic acids or their esters, a new technique has been proposed, which means that the decarboxylation of dicarboxylic acids or their hemi-esters is carried out under the influence of lead tetraacetate.

The process is conducted nrn 50-80 ° C in the presence of copper salts and pyridine nli acetonntril, and the molar ratio of lead tetraacetate and the original acid, it is advisable to take equal to 0.8-1.2-1.

Due to the fact that this process is inhibited by oxygen, it is conducted mainly in an inert atmosphere. As copper salts, mainly copper diacetate monohydrate is used in an amount of at least 0.1 mol.% Of the starting TAC. The process time at 75-80 ° C is 2 hours with a yield of up to 83%.

It should be noted that under these conditions, only one secondary group is decarboxylated.

Primary carboxyl primer, decarboxylating with 30 times slower, is not affected under these conditions. This ensures 100% selectivity of the process. Example. 10.3 g (40 mmol) dodecanedicarboxylic-1, 11 ACIDS, 1: g of copper diacetate monohydrate, 2.5 ML of pyridine and 100 ml of dry benzene are added to a flask with a stirrer, a reverse REFRIGERANT and device FOR

sprinkle up the burnt tetraacetate of the sunflower (TAS) in the atmosphere of an indoor gas. It placed 20 g (42 mmol) TAS. The flask is filled with nitrogen, the contents of the flask are heated to boiling (78-80), and the vortex is vigorously stirred for 1 hour, powdered with TAC. Mix up) and sit still for 30 minutes, then the reaction mixture is cooled and separated from the precipitate by filtration. The precipitate is washed

ether (2 times 25 ml each), the ether extracts are combined with the filtrate, washed with 20% NOY SALTIC OR 30% chloric acid,

sodium bicarbonate solution and water, then dried over anhydrous magnesium sulphate. After distillation of the solvent by distillation in vacuum, 7 g (83% of the theoretical) of a mixture of trideceno-11 and tridecene-12-oic acids in a ratio of 1: 2, m.p. 95-100 ° C / 0.08 mm Hg. Art. The composition of the mixture is established by the method of proton magnetic resonance.

In a similar way, undecen-4- and 5-oic acids (75%, kip. 85-90 ° / 0.06 mm Hg) were obtained from decanedicarboxylic acid, 4, from undecane-1-carboxylic acid-1,4-dodede- 4- and 5-oic acids (75%, 100-106 ° / / 0,07 mm of mercury.), From dodecanedicarboxylic-1,4 acid - tridecen-4- and 5-oic acids (80%, t. boils 105-llp ° / 0.07 mm Hg, from tetradecanedicarboxylic-1,4 acid - no-pentacene-4- and 5-oic acids (72%, kip. 110-115 ° / 0,007 mm hg. St. and from methyl ester of 12-carboxytridecanoic acid - methyl esters of tridecen-11-and 12-oic acids (85%, t. Kip. 50-5270.08 mm Hg. Art.).

Subject invention

Claims (3)

1. A method of producing higher 2-alkene acids or their esters is distinguished by the fact that, in order to simplify the process and increase the yield of the target product, the corresponding dicarboxylic acid or its half ester is subjected to decarboxylation under the influence of lead tetraacetate in the presence of copper salts and pyridine or acetonitrile at 50-80 ° C, followed by separation of the target product by known methods. 2. A method according to claim 1, characterized in that the starting acid and lead tetraacetate are taken in a molar ratio of 1 0.8-1.2. 3. Method according to paragraphs. 1 and 2, characterized in that the decarboxylation process is conducted in an inert gas medium.