Reductive Dehalogenation of Monobromo- and Tribromoacetic Acid by Sodium Borohydride Catalyzed by Gold Nanoparticles Entrapped in Sol–Gel Matrices Follows Different Pathways

An efficient, green, and reusable system comprising gold nanoparticles entrapped in an organically modified sol–gel silica matrix was found to catalyze the reduction of monobromo- and tribromoacetic acid by NaBH₄. Interestingly, the reduction of tribromoacetic acid yielded succinic acid along with acetic acid, whereas monobromoacetic acid was reduced only to acetic acid. The relative yields of succinic acid and acetic acid depended on the rate of addition of BH₄^–. Slow addition resulted in the formation of succinic acid as the major product. A variable product distribution was achieved as a result of the different pathways for dehalogenation.