| Summary: | 碩士 === 靜宜大學 === 應用化學系 === 90 === In the first part of electroreductive debromination, benzene is a mainly product from polybromobenzenes in the presence of H2(g) with LiClO4 as an electrolyte in MeOH/THF solution. This reaction condition is much better than the conditions under either N2(g) atmosphere or air. Reaction results suggest that a bromine situated at ortho position of another bromine atom is removed prior than others. Addition of basic ligands, such as cyclam and 2,2`-bipyridine, also led the better effect.
The efficiencies of various metals catalyzed hydrodebromination in the presence of H2(g) were studied in the second part. The results are summarized as following: (1) cyclam (0.0025 mM), NiCl2 (0.0025 mM), turnover number (TON) is 8912; (2) 2,2-bipyridine (0.0025 mM), NiCl2 (0.0025 mM), TON is 9948; (3) absence addition of ligand; NiCl2 (0.0025 mM), TON is 8524; (4) in the presence of N2(g); absence of ligand, NiCl2 (0.0025 mM), TON is 6432; (5) cyclam (0.0025 mM), CuCl2 (0.0025 mM), TON is 10208; (6) 2,2`-bipyridine (0.0025 mM), CuCl2 (0.0025 mM), TON is 8572; (7) absence of ligand; CuCl2 (0.0025 mM), TON is 7004. Reaction results showed the TON of Ni and Cu are very high.
In the final, 1,2,4,5-tetrabromobenzene was used for more intense studies under the presence of H2(g). During the reaction, the solution change from neutral to a strong acid indicated the formation of substantial amount of HBr. The H2(g), methanol, THF and H2O would be a source of hydrogen. The deuteriated solvents were used to illustrate the possible hydrogen source. No clear-cut for the hydrogen so far in our studies.
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