Study On Synthesis Of Tribromomethylarenes

Tribromomethylarenes are a kind of important intermediates for the synthesis of fine chemicals. Synthesizing trifluoromethylarenes are the most use of tribromo- methylarenes. And trifluoromethylarenes are widely used for the preparation of pesticide, pharmaceutical and materials. For example, 1,4-bis(tribromomethyl)- benzene is can be used to synthesize poly(α,α,α',α'-tetrafluoro-p-xylylene) which is a kind of material has excellent performance. 1-nitro-4-(tribromomethyl)benzene can be used for preparation some pesticides and pharmaceuticals such as fipronil, fluorochloridone, flufenamic acid and so on. Fluoxetine, a kind of anti-melancholia medicine can be synthesized from 1-chloro-4-(tribromomethyl)benzene.A novel method for synthesizing tribromomethylarenes under mild conditions was reported in this thesis. Tribromomethylarenes were synthesized under room temperature by bromide exchanging of trichloromethylarenes, which were prepared by chloridizing the corresponding methylarenes at first. At the same time, the influence factors and the mechanism of the reaction have also been studied. It was found that the reaction was accelerated obviously by the electron-donating substituting groups and decreased by the electron-withdrawing substituting groups and the reaction inhibited greatly when the groups were o-substituting groups. The conditions of synthesizing tribromomethylarenes were optimized and the mechanism of bromide exchanging of trichloromethylarenes was studied. In comparison to what described in the literatures, this synthetic strategy is superior in simple work-up, easily obtained materials, mild reaction conditions, simple disposal, high yield and purity.Tribromomethylbenzene, 1-fluoro-4-(tribromomethyl)benzene, 1-chloro-4-(tri- bromomethyl)benzene, 1-bromo-4-(tribromomethyl)benzene, 1-nitro-4-(tribromo- methyl)benzene, 1-bromomethyl-4-(tribromomethyl)benzene, 1-chloro-3-(tribromo- methyl)benzene, 1-bromo-3-(tribromomethyl)benzene, 1-fluoro-2-(tribromomethyl)- benzene, 1-chloro-2-(tribromomethyl)benzene, 1-bromo-2-(tribromomethyl)benzene, 1,3-bis(tribromomethyl)benzene, 1,4-bis(tribromomethyl)benzene and 4,4'-bis(tri- bromomethyl)biphenyl were synthesized by using this new method. These compounds and their corresponding precursors were characterized respectively. Among these fourteen compounds, 1-bromomethyl-4-(tribromomethyl)benzene, 4,4'-bis(tribromomethyl)biphenyl, 1-fluoro-2-(tribromomethyl)benzene and 1-bromo -2-(tribromomethyl)benzene are new compounds.In addition, the direct bromination of methylarenes using boron tribromide are studied in this thesis. It was found that the reaction didn't take place when the benzene ring has the electron-donating substituting groups. We didn't get pure single bromide product expect for a mixture of various benzyl bromides using this method.