| 摘要 |
In the present invention, there is described a process of reducing dehalogenation of aromatic halo derivatives in alkaline aqueous medium, wherein the process is characterized in that at a temperature ranging from 10 to 49 degC, there is added to an aqueous solution or colloidal solution of an aromatic halo derivative of the general formula I, in which A through E represent independently H, I, Br, Cl, COOH, NHi2, wherein at least one substituent is a halogen: a) water soluble base as a component A in molar ratio, relative to organically bound halogen in the aromatic halo derivative, in the range of 1:1 to 1:20, wherein there is used such an amount as to achieve the pH value of the resulting solution higher than 12; b) a reducing agent as a component B, being selected from the group consisting of sodium or potassium tetrahydroborate, a secondary alcohol containing 3 to 6 carbon atoms and with 1 to 2 OH groups and/or a reducing monosaccharide having 5 or 6 carbon atoms, in molar ratio relative to the organically bound halogen in the aromatic halo derivative, in the range of 1:1 to 20:1; c) a catalyst containing nickel as a component C, in molar ratio of nickel relative to the organically bound halogen in the aromatic halo derivative, in the range of 0.1:1 to 1:0.9. The thus obtained suspension is then mixed at a temperature ranging from 10 to 40 degC for a period of at least 60 minutes and at the most 72 hours. Subsequently, the mixing is stopped and the nickel sludge is separated by sedimentation optionally followed up with filtration or centrifugation. |
