DE918148C - Process for the production of furylnitroaethylene - Google Patents

Description

Process for the preparation of furylnitroethylene It is known that furylnitroethylene by condensation of furfural with nitromethane. For this purpose, an ice-cold solution of nitromethane in alkali lye is shaken with furfural and the furylnitroethylene formed is deposited by pouring it into acid, the yield in larger batches being only 55 to 70% of theory. In the known process, the crude product is sharply dried and recrystallized from ligroin. During the necessary drying, losses occur again due to decomposition.

It has now been found that by adding an alcohol, preferably Methanol, of which the alkali lye can be used to increase the yield considerably. That is probably due to the fact that the alcohol acts as a solubilizer for the furfural serves. It is particularly advantageous to carry out the reaction in the presence of a Alcohol at temperatures below 0 °, preferably at -15 to -5 °.

A further improvement is achieved in that the obtained Raw furylnitroethylene without special drying, i.e. moist with a suction filter, in a hot one Chlorinated hydrocarbon, e.g. B. carbon tetrachloride, dissolved and separated from the water is separated. The solution crystallizes from the hot, filtered solution on cooling Furylnitroethylene completely pure. The yield of pure crystals is 83 to 89 per cent of the theoretical yield.

EXAMPLE i 1409 nitromethane is added dropwise to a solution of 160 g of NaOH in 8oo ccm of water and 200 ccm of methanol with stirring at -15 ° in the course of about 30 minutes. The temperature can rise to - 10 ° '. After adding 1 l of ice water, 200 g of furfural are stirred in at -10 to -5 ° over the course of about 20 minutes, then 1 l of ice-water is added and the mixture is stirred for 10 minutes. The clear solution is poured into dilute sulfuric acid (25o ccm of concentrated H2 S 04 in 2 l of water), the furylnitroethylene crystallizing out. The yellow precipitate is sucked off sharply and then dissolved in 700 cc of hot carbon tetrachloride, the separated water is lifted off, the carbon tetrachloride solution is filtered and allowed to crystallize. Yield: 238 g. Evaporation of the mother liquor gives a further 17 g, increasing the yield to 255 g, equal to 89%.

The purified furylnitroethylene is expediently under nitrogen Stored in a tan bottle as it is even at room temperature below the action of light and air slowly decomposes, with a color change of Intense yellow over brown to white occurs with the escape of nitrous gases.

Example e A solution of 16 g cooled to about -10 to -15 ° NaOH, 8o ccm of water and 2o ccm of ethanol are added with stirring for 7 minutes 14 g of nitromethane are added. Thereupon 100 cc of ice water and then within 4 Minutes 20 g of furfural slowly added, again 100 ccm of ice water added and the reaction solution was stirred for 15 minutes. The temperature is not supposed to rise above o °.

The solution is slowly stirred into 2–25% sulfuric acid, the precipitated yellow crystal mass is suctioned off and recrystallized from carbon tetrachloride. Yield: 25 g, equal to 86.5%.

Claims (2)

PATENT CLAIMS: i. Process for the preparation of furylnitroethylene from furfural and nitromethane in the presence of alkali, characterized in that the condensation is carried out with the addition of an alcohol, preferably from 1 to 2 parts of methanol to 1 part of furfural, and the furylnitroethylene formed is purified, if necessary, by recrystallization from a chlorinated hydrocarbon . 2. Procedure according to claim i, characterized in that the reaction at temperatures below from 0 °, preferably at -15 to -5 ", is carried out.