| 摘要 |
<PICT:1105805/C2/1> Lactams are prepared by a continous process by the Beckmann rearrangement of one or more cyclic, preferably C5- 15, ketoximes in a rearrangement mixture, including sulphuric acid, oleum or phosphoric acid, together with recycled previously prepared lactam, which is continuously circulated through a circuit and the acid and the oxime are each injected separately into the circulating reaction mixture through separate nozzles, the nozzles being substantially separated and each being positioned before a throughflow mixer, the outlet velocity of the oxime and that of the acid from the nozzles being at least twice the flow velocity of the rearrangement mixture and the ratio of the rate of flow by volume of the rearrangement mixture per hour to the volume of the oxime introduced per hour being 50:1 to 150:1. Suitably the acid and the oxime are each injected at from 3 to 15 m./sec. through a nozzle 13 located within a tubular part of the circuit 3 and 6 and having a plurality of fine orifices having diameters of 0.5 to 2 mm. out of which the acid or oxime is ejected as filaments 16. Each nozzle 13 is positioned before a mixing device 17 and the nozzles are located at positions 3 and 6 sufficiently far apart that complete homogenization of one reagent into the rearrangement mixture is effected before the other reagent is introduced. |
