| 摘要 |
<p>Nitroguanidine is prepared from guanidine nitrate by the action of aqueous sulphuric acid and, optionally, nitric acid. In this process the reconcentrated sulphuric acid obtained from the preceding step is used, the reaction being carried out using from 2.5 to 3.5 mol of sulphuric acid per mol of guanidine nitrate. The dehydration is carried out using from 82 to 85 % by weight strength sulphuric acid at a temperature of from 40 to 80 DEG C, preferably from 40 to 60 DEG C, for from 1 to 3 hours. The sulphuric acid is then diluted, by adding water or wash acid at 0 to 5 DEG C from a previous step, to from 25 to 35 % strength by weight. After the nitroguanidine which has precipitated has been separated off, the sulphuric acid diluted to from 25 to 35 % strength by weight is reconcentrated to be used again.</p> |
