DE1568208C - Process for the production of glycidamide - Google Patents

Claims (1)

^1st '·''·. ■■■ \'. ² ■■■ '.. ·. ■■■. · The manufacture of. Recover glycidamide by reacting and then reuse; For acrylonitrile with hydrogen peroxide in aqueous .. it is advisable to leave the reaction mixture to a post-reaction pH value of 6.0 to 9.0 several times after the end of the riger or aqueous-alcoholic solution with an addition of hydrogen peroxide, in order to be largely prescribed . In all known processes, the consumption of hydrogen peroxide is achieved
the destruction of unreacted hydrogen peroxide glycidamide is indicated as an intermediate pronoun after the reaction has ended. According to the process of the USA patent specification for the technical production of textile auxiliaries. 3,053,857 means, plasticizers, dyes and plants, it is carried out by treatment with palladium on animal. Protective agents,
coal, according to the procedure of the German patent io _R ■■ _ ·> |
font 1154 086 by treating the reaction -. ^P '.
mixed with oxides of manganese, lead or to 795 g (15 mol) of acrylonitrile and 4500 g of vanadium. The highest yield is with these. Distilled water is allowed to 58% of theory given with vigorous stirring, known methods. 459 g (13.5 moles) of hydrogen peroxide (1315 g of a It has now been found that glycidamide 15 (35% strength hydrogen peroxide solution) can be carried out within 1.5 hours Reaction of acrylonitrile with hydrogen. which drip in so that through the released peroxide at a pH of 7.0 to 8.0 in aqueous heat of reaction, a reaction temperature of 45 ° C Solution or aqueous suspension is essentially maintained. The pH is through higher yields than with the known processes, addition dropwise of aqueous 2-sodium hydroxide solution konauch held at 7.0 to 7.6 without subsequent treatment with an ao. The concentration of the Metal or metal oxide is obtained when the water-hydrogen peroxide is exceeded during the reaction substance peroxide the acrylonitrile continuously in the period 5 percent by weight, based on acrylonitrile, That the hydrogen peroxide content does not add to the extent. The reaction mixture will. at the same Reaction mixture 5 percent by weight, based on pH for a further hour at the temperature of available acrylonitrile, not exceed. 25 45 ° C held and then under reduced The conversion of the acrylonitrile is done by putting pressure, at about 30 torr and 40 ° C, as much as possible Hydrogen peroxide, preferably concentrated from 3 to 50% by weight, whereby 180 g (corresponding to about 3.4 mol) percent aqueous solutions to which unreacted acrylonitrile dissolved in water is recovered, or suspended acrylonitrile to the extent that the glycidamide in the residue is in how it is consumed. The ratio of the weight 30 acetone added, the solution obtained with amounts of acrylonitrile to water is generally dried in sodium sulfate, the solvent below Range 1:20 to 1: 2, in particular 1:10 to 1: 4. distilled off reduced pressure at 40 ⁰ C and that The concentration of hydrogen peroxide obtained crude product is kept at 0.2 torr, with in the reaction mixture, based on the 875 g of pure glycidamide present with a melting point of Acrylonitrile, always below 5 percent by weight. It is 35 33 to 34 ° C can be obtained. The yield is expedient, also local excesses of this 86.6% of theory, based on consumed acrylic Avoid concentration limit, e.g. by nitrile. . . intensive mixing or even, extensive example 2 Distribution of the hydrogen peroxide. To check ■ the hydrogen peroxide concentration or the acrylic 40 In a stirred tank of 501 content, which determines the nitrile concentration from time to better mixing with an external constraint 'time, z. B. by iodometric titration or by circulation, is allowed to 5.3 kg (100 mol) of gas chromatography, and regulates accordingly the acrylonitrile and 30 kg of water 3.06 kg (90 mol) of hydrogen peroxide supply. The maintenance of the pH hydrogen peroxide (8.74 kg of a 35% water value is carried out with means known per se, such as those 45 peroxide solution). as indicated under Example 1, run in as described in the already known processes. After the addition of the hydrogen peroxide have been made. the reaction mixture is still 1 hour at pH 7.0 The reaction is expediently kept at room temperature up to 7.6 and 45 ° C and then how ■ rature or a little above, ie approximately in the range described under Example 1, worked up. .30 to 60 ° C, especially at about 40 to 50 ° C. 50 1.22 kg (corresponding to about 23 mol) In the process according to the invention, it prepares unreacted acrylonitrile and recovered no difficulty, the temperature even with the largest 5.05 kg of pure glycidamide from melting point 33 to To keep approaches while you get 34 ° C with known Ver. The yield is 75.3% drive had to apply carbon dioxide cooling. Theory, based on acrylic acid nitrile consumed. It is surprising that with this method 55 can achieve significantly shorter response times, '. Claim:
than they were previously given. In general is the exothermic reaction after 1 '/ ₂ hours full process for the production of glycidamide by constantly. With larger batches or with continuous reaction of acrylonitrile with hydrogen execution, besides the hydrogen peroxide at a pH value of 7.0 to 8.0 in peroxide, acrylonitrile is also used in the amount of the reaction aqueous solution or aqueous suspension, d agemic to how it is consumed. It is advantageous, characterized in that the water is continuously present in the excess acrylonitrile in the reaction mixture, even if at the end of the reaction it is still superfluous peroxide to the acrylonitrile . Measure is supplied that the hydrogen peroxide is, e.g. B. 5 to 25 mol percent, based on the 65 used content in the reaction mixture 5 percent by weight, acrylonitrile. You can do it in the work-up based on the acrylonitrile present, not over- reaction mixture, z. B. by distillation, increases slightly.