| 摘要 |
An improved process for the preparation of monoaryl thiourea compounds, in which a salt of an arylamine is reacted with ammonium rhodanide or an alkali metal rhodanide in an aqueous medium; the improvement consists in that the reaction is carried out in a reaction mixture which at the start contains a higher amount by weight of the salt of the arylamine than of water and contains 1 to 1.25 times the equivalent amount of the rhodanide calculated on the arylamine, and which does not contain any excess acid, and that the reaction is carried out at a temperature which is below the boiling point of the reaction mixture by at least 5 DEG C. It is advantageous, but not compulsory, to effect the reaction while using from 5 to 10 mol % of hydrogeno-sulfite ions, in order to remove sulfur-containing by-products which are formed as a consequence of the acid spontaneous decomposition of the rhodanide in an inevitable side reaction. By means of the improved novel process, homogeneous monoaryl thioureas are obtained in a high yield with a reduced charge of the waste water.
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