DE1233851B - Process for the preparation of cis-3-chloroacrylic acid - Google Patents

Description

Process for the preparation of cis-3-chloroacrylic acid The invention refers to a novel process for the production of cis-3-chloroacrylic acid, in which the formation of the corresponding trans isomer is completely excluded is.

It is known that a mixture of cis- and trans-3-haloacrylic acids can be obtained by reacting hydrochloric acid with propiolic acid (Recueil des Travaux Chimiques, Vol. 54, 1935, p. 167; Journal of the American Chemical Society, Vol. 76, 1954, pp. 627 to 629; Beilstein's Handbook of Organic Chemistry, 4th edition, 3rd supplementary work, Vol. 2, Part 2, 1961, p. 1243). According to this, the cis and kans isomers can be separated by fractional crystallization, but has become through the discovery of the high and diverse biological effects of the cis isomer in contrast to the moderate effect of the trans isomer, the necessity a less cumbersome, less time-consuming and cheaper process for the production of cis-3-chloroacrylic acid. These two isomers were for example on their suitability as soil fungicides against Rhizoctonia solania and Fusarium oxysporum f. Lycopersici examined using artificially inoculated soil and the amount used corresponded to about 68 kg per 0.4 ha ; the cis isomer prevented any mycelial growth of fungi, while the Use of the trans isomer about half of the soil surface with (mycelium) mold was covered.

In the comparative experiment, in which no active ingredient was used, was the soil surface completely covered with mycelium.

The process of the invention now allows the production of 3-chloroacrylic acid with a much higher proportion of the cis isomer than was previously possible, and in its preferred embodiments even leads to the formation of pure cis-isomers, whereby the starting materials are completely converted.

The process of the invention for the preparation of cis -3-chloroacrylic acid by cis-directed addition of hydrochloric acid to the triple bond of propiolic acid is characterized in that propiolic acid or its alkali metal salts are used with an aqueous solution of hydrochloric acid at temperatures from 0 to 110 ° C in the presence of 0.05 to about 20 mol percent, preferably 2 to 10 mol percent, based on the amount of propiolic acid, a copper, chromium, mercury, manganese, Iron, zinc, cadmium or aluminum salt as a catalyst and optionally in In the presence of an organic solvent or diluent.

Propiolic acid or its alkali salt used as the starting material can be used as such or in the form of a solution or slurry, in which this compound is contained dispersed around this. B. the implementation of the corresponding acetylide has been obtained with carbon dioxide.

The hydrochloric acid is used as an aqueous solution that preferably contains 10 to 50 percent by weight acid. In general, this is molar Ratio of hydrochloric acid to propiolic acid between about 1: 1 or less and 3: 1 or more.

Is the formation of the alkali metal salt of cis-3-chloroacrylic acid desired directly from the corresponding alkali metal salt of propiolic acid, so must equimolar amounts of hydrochloric acid and the alkali salt of propiolic acid used to avoid subsequent neutralization.

In general, however, an excess of hydrochloric acid is expedient. z. B. 2 to 3 moles per mole of propiolic acid, used to complete the reaction ensure the propiolic acid or its alkali salt.

The special feature of the method of the invention consists in the Presence of a cupri, cupro, mercury, mercuro-, chromi-, chromo-, mangani-, F-erri, ferrous, zinc, cadmium or aluminum salt as a catalyst. These cations improve the overall yield of cis-3-chloroacrylic acid and effect particularly the preferred salts of chromium, mercury and especially copper to be used -that a complete conversion of the propiolic acid into the cis-isomer takes place, with the formation of the trans form is largely or even completely avoided. That Anion of these metal salts does not seem to play a particular role in the implementation and can be any inert inorganic anion, such as the chloride, bromide, Sulfate or sulfite.

The temperature used should not be above 110 ° C, as found was that isomerization to the trans isomer can then take place.

At temperatures well below 0 ° C, the deposition is too slow. It has been found that using the preferred catalytically active Metal salts the most favorable temperature is between about 50 and 110 ° C. Because the implementation is exothermic, is a cooling device to absorb the heat generated necessary to keep the reaction temperature within the required range to keep.

The process of the invention can be carried out batchwise or continuously be performed. In the case of batch implementation, the reaction time is between about 30 minutes and 24 hours, but under the preferred conditions im general response times between about 1 hour and one hour for a complete Implementation from.

A high reaction temperature requires relatively short reaction times, when the preferred catalytic amounts of a metal salt are used. at the continuous implementation of the reaction, the residence time is in a tubular Reaction vessel preferably between about 1 and 15 minutes at the most favorable reaction temperature.

The aqueous hydrochloric acid used in the process is at the same time diluent or solvent, but also another one can also be used inert organic solvents or diluents are used, such as xylene, Toluene, kerosene, paraffinic hydrocarbons, e.g. B. heptane, or cycloparaffinic hydrocarbons, z. B. Cyclopentane.

The recovery of the cis-3-chloroacrylic acid from the reaction mixture takes place in the usual way, e.g. B. by extracting with a suitable for this purpose Solvents such as chloroform, benzene, toluene or xylene. Purification of cis-3-chloroacrylic acid is carried out by recrystallization from a suitable solvent, e.g. B. to the Extraction used solvent or hexane, or even by fractionated Distillation in vacuo.

Example 1 A 250 cm capacity, equipped with a stirrer Flask was purged with nitrogen; then 81 com 12 normal aqueous hydrochloric acid became and 3 g of cuprous chloride (3.1 mole percent) are added to the flask. Thereupon 33, 8 g propiolic acid slowly with stirring and under a nitrogen atmosphere in 25 Minutes added, the temperature being 8 to 12 ° C. The resulting mixture was stirred at 0 ° C for 24 hours to ensure complete conversion. The reaction mixture was extracted six times with 100 com of chloroform each time.

After evaporation of the chloroform and recrystallization of the The residue from heptane was 42.1 g of cis-3-chloroacrylic acid with the melting point from 60 to 62 ° C obtained, corresponding to the yield of 82%, based on the propiolic acid, with no trans isomer being present.

Example 2 1 mole of propiolic acid slowly rose to 350 cm 12 normal given aqueous hydrochloric acid containing 0, 025 mole of copper (I) sulfate (2.5 mole percent). The addition took place within one hour, the reaction temperature between 35 and 40 ° C. After the reaction mixture is another hour at this temperature was stirred, the reaction product was extracted and distilled, whereby the cis-3-chloroacrylic acid was obtained in quantitative yield.

Example 3 1 mole of propiolic acid became 350 com 12 normal in one hour given aqueous hydrochloric acid containing chromium chloride (2.5 mole percent), with the reaction temperature was 35 to 40 ° C. After the reaction mixture another After stirring at that temperature for one hour, the reaction product was extracted and distilled, whereby the cis-3-chloroacrylic acid is obtained in 75% yield became ; the trans isomer was absent.

When using manganese chloride, aluminum trichloride or cadmium chloride Instead of the cuprous chloride, an 80 to 90% conversion of the propiolic acid was used achieved in 3-chloroacrylic acid.

Example 4 To a mixture of 6 g of cuprous chloride (4.0 mol percent) and 164 com of 12N aqueous hydrochloric acid became 68 g of sodium propiolate in one hour given.

The temperature of the reaction mixture was 0 to during the addition 10 ° C. After the reaction mixture is stirred for another 35 minutes on this The mixture was maintained five times with 100 com of chloroform each time extracted.

After evaporation of the chloroform, 83.3 g of residue were obtained, which contained 77 percent by weight cis-3-chloroacrylic acid. The trans isomer was not present as determined by infrared inspection.

Example 5 A mixture of 5.77 g of cuprous chloride (= 3 mol percent) and 158 com of 12N aqueous hydrochloric acid was heated to 50 ° C; then turned 90 g of crude sodium propiolate obtained by carboxylating 46.5 g of sodium acetylide with Carbon dioxide was added to the mixture in 14 minutes; this mixture was held at 50 ° C. for a further 16 minutes with stirring. The reaction mixture then became extracted six times with 100 cc of chloroform each time. After evaporation of the chloroform 70 logs of a residue were obtained, the 88 percent by weight of cis-3-chloroacrylic acid contained, trans-3-chloroacrylic acid was not present.

Example 6 A slurry of crude sodium propiolate in 200 com Xylene obtained by carboxylating 57 g of sodium acetylide with carbon dioxide was, with stirring in 20 minutes to a mixture of 7.16 g of cuprous chloride (= 5.8 mol percent) and 195.6 g of concentrated hydrochloric acid are added, whereby the reaction temperature was 50 ° C. Then the reaction mixture became an additional 26 Maintained at 45 to 54 ° C for minutes. The xylene and the aqueous layer were separated ; the aqueous layer was extracted four times with 100 com of chloroform each time.

The chloroform extract was combined with the xylene layer; these Solvents were then evaporated to give 119 g of a residue, of 52 percent by weight cis-3-chloroacrylic acid and 1 percent by weight trans-3-chloroacrylic acid contained.

The cis acid was obtained by recrystallization from hexane or by vacuum distillation further cleaned.

Example 7 62.6g crude sodium propiolate containing 41.8% (0.285 moles) Contained sodium propiolate and the remainder of inert sodium salts and diethyl diethylene glycol, were added in 7 minutes to 112 com of 12 normal aqueous hydrochloric acid, which contained 11.2 g (0.041 mol = 14.4 mol percent) mercuric chloride, the reaction temperature Was 50 to 54 ° C. After these 7 minutes, the reaction mixture became another Maintained at this temperature for an hour with external cooling. The reaction mixture was filtered after cooling to room temperature, and from the filter cake were all water-soluble salts are washed out with water. The filtrate was made with chloroform extracted, the extracts were vacuum in a 30 cm long so-called)) Vigreux (-Column distilled, whereby a distillate was obtained which the cis-3-haloacryl- acid contained in an amount which corresponded to 66.4% of the theoretical amount on the sodium propiolate. The trans isomer content was less than 8% based on the sodium propiolate.

Claims (2)

Claim: Process for the production of cis-3-chloroacrylic acid by cis-directed addition of hydrochloric acid to the triple bond of propiolic acid, characterized in that one propiolic acid or its alkali metal salts with an aqueous solution of hydrochloric acid at temperatures from 0 to 110 ° C in the presence of 0.05 to about 20 mol percent, preferably 2 to 10 mol percent, based on the amount of propiolic acid, a copper, chromium, mercury, manganese, Iron, zinc, cadmium or aluminum salt as a catalyst and optionally in Reacts in the presence of an organic solvent or diluent. Publications considered: German Auslegeschriften No. 1,044,069, 1,044,070; Beilstein's Handbook of Organic Chemistry, 4th Edition, 3rd Edition Supplementary work, vol. 2, part 2, 1961, p. 1243; Journal of the American Chemical Society, Vol. 76, 1954, pp. 627-629; Recueil des Travaux Chimiques, Vol. 54, 1935, P. 167.