| 摘要 |
A process for the preparation of 3-amino-1, 2. 4-benzotriazine 1,4-dioxide (ABD) comprises: (a) adding a solution of benzofurazan- 1 oxide in DMSO in a molar ratio of 1 to 3 to a solution of disodium cyanamide in water in a molar ratio of 3 to 2 contained in a reaction vessel at a temperature of 55-65 deg C to obtain the sodium salt of ABD as a precipitate; (b) removing the precipitate and suspending it in excess water; (c) adding about 3-5 mole equivalents of methanesulphonic acid to the suspension to obtain a solution; (d) filtering the solution to remove acid insoluble impurities; (e) charging the filtered solution into a buffered solution containing excess sodium acetate and allowing crystallisation to occur; (f) filtering and washing the crystalline particles with water; (g) charging the washed crystalline particles back into the reaction vessel and stirring it with about five volumes of water; and (h) filtering the crystalline particles and rinsing them with acetone to obtain the purified ABD. |
