| 摘要 |
1324276 Biuret DOW CHEMICAL CO 8 Oct 1970 [9 Oct 1969] 47932/70 Heading C2C A process for preparing biuret comprises heating a mixture of (a) a pyrolysed urea feedstock having a maximum biuret content of 55 weight per cent and (b) a biuret-urea pyrolysate having a maximum urea content of 15 weight per cent and a minimum biuret content of 60 weight per cent, the overall urea content of the mixture being less than 20% by weight, at a temperature of from 100‹ to 150‹ C. for from 10 minutes to 8 hours in the presence of an inert liquid hydrocarbon which is at reflux at the temperature of heating, the mixture : hydrocarbon weight ratio being from 5 : 95 to 60 : 40. The pyrolysed urea feedstock is suitably obtained by initially heating urea at from 150‹ to 240‹ C. and then at a temperature of from 110‹ to 145‹ C. in the presence of an inert gas sparge to remove by-product ammonia. |
