Photocatalytic oxidative benzylic bromination with hydrobromic acid (HBr) and hydrogen peroxide (H2O2) is a green process for the synthesis of benzyl bromides, but suffers from the risk of explosion when… Click to show full abstract
Photocatalytic oxidative benzylic bromination with hydrobromic acid (HBr) and hydrogen peroxide (H2O2) is a green process for the synthesis of benzyl bromides, but suffers from the risk of explosion when performing it in a batch reactor. This disadvantage could be overcome by running the reaction in a microchannel reactor. In this work, a green and safe process for the synthesis of 2,6-dichlorobenzyl bromide (DCBB) was developed by conducting selective benzylic bromination of 2,6-dichlorotoluene (DCT) with H2O2 as an oxidant and HBr as a bromine source in a microchannel reactor under light irradiation. The reaction parameters were optimized, and the conversion of DCT reached up to 98.1% with a DCBB yield of 91.4% under the optimal reaction conditions.
               
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