| 摘要 |
PURPOSE:To obtain the titled compound as an intermediate for medicines, readily, by the dehydration of a trimethoxybenzoic acid without using a dryer through the heating distillation together with a hydrocarbon solvent having specific characteristics, and directly the subsequent halogenation in the presence of a catalyst. CONSTITUTION:A trimethoxybenzoic acid, preferably 3,4,5-trimethoxybenzoic acid, is dehydrated by the heating distillation with a hydrocarbon solvent, preferably e.g. toluene or xylene, having a boiling point in the range of 50-200 deg.C and a solubility in water of 1% or below and a solubility of water of 1% or below, and forming an azeotropic mixture with water, to decrease the moisture in the raw material mentioned above to 0.001-2%, preferably 0.01-0.05%. The solution containing the above-mentioned trimethoxybenzoic acid is directly halogenated with an acid-halogenating agent, preferably thionyl chloride, in the presence of a catalyst, e.g. N,N-dimethylformamide, to give the titled compound. |
