| 摘要 |
To produce technical TRIFEURALIN with a nitrosoamine content not exceeding 1 ppm, for use as a herbicide, DINITRO-PCBT free from nitrosating agent is prepared by a process in which DINITRO-PCBT is treated with an aqueous bisulphite solution having a SO2 concentration of between 1% and 5% at a pH of between 1 and 3, at a temperature of between 50 DEG and 100 DEG C for a time of between 1 and 3 hours. The organic layer is then separated from the aqueous layer, and the acidity and last traces of the bisulphite solution are eliminated from the organic layer by means of an aqueous alkaline solution.
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