Related Experiment Video
Updated: May 4, 2026

Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
Published on: November 30, 2022
Electrophilic bromination of substituted stilbenes and stilbazoles: a quantum-chemical investigation
Linda J McAllister1, Duncan W Bruce, Peter B Karadakov
1Department of Chemistry, University of York, Heslington, YORK YO10 5DD, UK. peter.karadakov@york.ac.uk.
Abstract:
In order to study the effect of substituents on the electrophilic bromination of stilbenes and stilbazoles, the geometries of the reaction intermediates were optimised at the MP2/6-31G(d,p) and M06-2X/6-31G(d,p) levels of theory. Stilbenes with two electron-withdrawing substituents are shown to favour bromonium ion intermediates, whereas the presence of an electron-donating substituent leads to a carbocation intermediate. These observations are rationalised by means of Hammett and Taft parameters. Localised molecular orbitals indicate that the bonding between the bromine atom and the carbon atoms in the stilbene varies from a σ-bond in a carbocation intermediate to a 3-centre-2-electron bond in a bromonium ion intermediate. Natural bond orbital (NBO) analyses reveal that carbocation intermediates are stabilised by resonance. The optimised geometries of charge-transfer complexes, the pre-reactive intermediates formed between molecular bromine and the stilbene, show that these species can be considered as halogen-bonded complexes with binding energies ranging from 14.5 to 20.1 kJ mol(-1).
More Related Videos
07:50Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
08:46Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI
Published on: November 22, 2016
Related Concept Videos
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
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 Substitution: Allylic Bromination
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Regioselectivity of Electrophilic Additions-Peroxide Effect