Related Experiment Video
Updated: Jul 3, 2026

Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)
Published on: December 29, 2016
A xerogel-sequestered selenoxide catalyst for brominations with hydrogen peroxide and sodium bromide in an aqueous
Stephanie M Bennett1, Ying Tang, Danielle McMaster
1Department of Chemistry, University at Buffalo, The State University of New York, 627 Natural Sciences Complex, North Campus, Buffalo, New York 14260-3000, USA.
Abstract:
4-(Hydroxymethyl)phenyl benzyl selenoxide (4) sequestered in a halide-permeable, Class II xerogel formed from 10/90 (mol/mol) 3-aminopropyltriethoxysilane/tetraethoxysilane catalyzes the bromination of organic substrates (4-pentenoic acid, 3,5-dihydroxybenzoic acid, 1,3,5-trimethoxybenzene, N-phenylmorpholine, and N,N-dimethylaniline) with NaBr and H2O2. Catalyst performance (reaction rate) when sequestered within the halide-permeable xerogel is 23-fold greater in comparison to xerogel-free catalyst in solution. The catalyst is easily separated from the reaction mixture via filtration and the recovered catalyst can be reused without loss of activity through formation of the first 80 mol of product per mole of catalyst.
Related Concept Videos
Formation of Halohydrin from Alkenes
Radical Substitution: Allylic Bromination
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Radical Anti-Markovnikov Addition to Alkenes: Overview
α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction
Radical Anti-Markovnikov Addition to Alkenes: Mechanism
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...

