Synthesis Of The Intermediate Of Fludioxonil And Optimization Of Preparation Technique

The preparation for 4-amino-2,2-diflurobenzodioxole which is an intermediate of fludioxonil is emphatically discussed. Catechol as raw material, the intermediate 4-amino-5,6-dichloro-2,2-diflurobenzodioxole was prepared through six reactions including etherification, chlorination, fluorination,chlorination, nitration, reduction.1,3-Benzodioxole was synthesized by the reaction of catechol with excessive di-chloromethane under alkaline conditions in the autoclave.Through the steam distillation and vacuum distillation,the pure product was obtained with high yield.2,2-di-chlorobenzodioxole was obtained by treating 1,3-Benzodioxole with Cl₂ via radical induced reaction under nitrogen atmosphere.Also the mechanism of the formation of the by-product catechol carbonate was discussed.(HF)₃-triethylamine as the fluorination reagent, 2,2-diflurobenzodioxole was obtained through chlorine-fluorine exchange reaction. A favorite reaction condition was obtained after we studied the influence of the amount of (HF)₃-triethylamine. Then the chloride was obtained by the reaction with Cl₂ at room temperature. Iron powder was used as a catalyst.Then the nitrate was obtained by using mixed acid as the nitration reagent.Besides, we studied the influence of the amount and composition of the mixed acid .In the last step, 4-amino-5,6-dichloro-2,2-diflurobenzodioxole was obtained through reduction with hydrogen.we made an analysis of the possible problems and put forward some relevant proposals.