| Abstrakt: |
Although the brominated flame retardant 1,2,5,6,9,10-hexabromocyclododecane (HBCD) has been widely used to reduce the flammability of polymeric materials, it is a toxic and persistent organic compound. In this paper, we report an efficient method for the debromination of HBCD by using a Pd-catalyzed system. HBCD was completely debrominated to the C 12 cyclic compounds such as cyclododecatriene, cyclododecadiene, and cyclododecene in a solution of 2-propanol/methanol (99:1, v/v) containing dissolved NaOH in the presence of a silica-supported Pd catalyst (Pd/SiO 2 ) at 35 °C. The reaction achieved product yields of 92% for the bromine-free products and 94% for the released Br ions. In the absence of Pd/SiO 2 , HBCD was partially debrominated to yield penta-, tetra-, and tribrominated C 12 cyclic compounds. The HBCD debromination pathway seems to involve both HBr elimination by reaction with NaOH and Pd-catalyzed hydrodebromination by hydrogen transfer from 2-propanol. [ABSTRACT FROM AUTHOR] |
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