| 摘要 |
The invention relates to a method for producing N-(phosphonomethyl)glycine involving the following steps: (a) oxidizing N-(phosphonomethyl)iminodiacetic acid (PMIDA) with peroxides or oxygen in an aqueous medium and in the presence of a heterogeneous catalyst at a temperature ranging from 50 to 150° C.; (b) subsequently separating the solid catalyst out of the aqueous reaction suspension of step (a); (c) concentrating the clear reaction solution from step (b), especially by evaporation, and; (d) separating the N-(phosphonomethyl)glycine out of the concentrated reaction solution from step (c), especially by filtration. According to the invention, the aqueous reaction solution from step (d) (mother liquor) is returned with small amounts of N-(phosphonomethyl)glycine and byproducts to step (b) (catalyst separation) and/or to step (c) (concentration). This results in distinctly increasing the yield with a constant product purity and in noticeably reducing the amount of mother liquor.
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