DE1568208B - - Google Patents

Claims (1)

Recover the production of glycidamide by reacting and then reusing it. It is made of acrylonitrile with hydrogen peroxide in aq- '.-. It is advisable to leave the reaction mixture to a post-reaction pH value of 6.0 to 9.0 "after completion of the aqueous or aqueous-alcoholic solution with an addition of hydrogen peroxide" To achieve hydrogen peroxide,
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 3,053,857 for the technical production of textile auxiliaries, plasticizers, ... dyes and plants, it is carried out by treatment with palladium on animal protection agents,
coal, according to the method of the German patent io _R · · ι ι
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 Vanadins. The highest yield is this distilled water is left with vigorous stirring known method 58% of theory indicated. 459 g (13.5 moles) of hydrogen peroxide (1315 g of a It has now been found that 15 35 ° / _o solution of hydrogen peroxide) the glycidamide dropwise within 1.5 Stundurch reacting acrylonitrile with hydrogen so that by the released peroxide at a pH of from 7.0 to. 8.0 in aqueous heat of reaction, a reaction temperature of 45 ° C solution or aqueous suspension is substantially maintained. The pH value is kept at 7.0 to 7.6 by means of higher yields than in the known processes, the dropwise addition of aqueous 2-sodium hydroxide solution, even without subsequent treatment with a 20 stant. The concentration of the metal or metal oxide is obtained when the water-hydrogen peroxide is exceeded during the reaction substance peroxide to the acrylonitrile continuously in the period 5 percent by weight, based on acrylonitrile, that the hydrogen peroxide content is not added. With the same reaction mixture, the reaction mixture will not exceed 5 percent by weight, based on the pH, for a further hour at the temperature of the acrylonitrile present. 25 45 ° C held and then under reduced The reaction of acrylonitrile by pressure at about 30 Torr and 4O ⁰ C, as far as possible Hydrogen peroxide, preferably 3 to 50 weight-concentrated, 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 ⁰ C can be obtained. The yield is expedient, also local excesses of this 86.6% of theory, based on consumed acrylic To avoid concentration limit, e.g. B. by nitrile. intensive mixing or even, extensive ....... B e i s d i e 1 2 Distribution of the hydrogen peroxide. For checking 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 forced time, z. B. by iodometric titration or by circulation is allowed to 5.3 kg (100 mol) of gas chromatography, and accordingly regulates the acrylonitrile and 30 kg of water 3.06 kg (90 mol) of hydrogen peroxide supply. The compliance of the pH of hydrogen peroxide (8.74 kg of a 35 ° / _o ^e n ig water value is carried out with means known per se, such as peroxide solution 45) as indicated in Example 1, run in described in the already known methods. 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, d. H. approximately in the range described under Example 1, worked up. 30 to 6O ⁰ C, in particular at about 40 to 50 ⁰ 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 at a known temperature. The yield is 75.3. ° / ₀ drive had to apply carbon dioxide cooling. Theory, based on acrylic acid nitrile consumed. It is surprising that 55. . ' : Allow significantly shorter response times to be achieved, patent claim:
than they were previously given. In general is the exothermic reaction after IV2 hours full process for the production of glycidamide through constant. With larger batches or with continuous reaction of acrylonitrile with hydrogen Execution is carried out in addition to the hydrogen peroxide at a pH of 7.0 to 8.0 in peroxide and acrylonitrile to the same extent as the reaction aqueous solution or aqueous suspension, mixed with it to how it is consumed. It is advantageous, characterized in that the water if even at the end of the reaction over substance peroxide the acrylonitrile continuously in the excess acrylonitrile present in the reaction mixture is added to the extent that the hydrogen peroxide is z. B. 5 to 25 mol percent, based on the amount of 65 used in the reaction mixture 5 percent by weight, Acrylonitrile. It can be used in the work-up of the acrylonitrile present, not over-reaction mixture, z. B. by distillation, increases slightly.