Project: Towards molecular control of electrophilic aromatic substitution reactions in homogeneous and heterogeneous environments through a combined ab initio molecular dynamics and conceptual density functional theory approach.

2019-01-01 – 2022-12-31

Abstract

The electrophilic aromatic substitution (SEAr) is a cornerstone reaction discovered by Friedel and
Crafts in the 19th century. Despite its industrial importance for ethylbenzene production, the
reaction mechanism is still debated. The proposed mechanistic pathway, relying on the formation of
arenium ion intermediates, was recently challenged on experimental and theoretical grounds. The
formation of the commonly assumed Wheland intermediate may critically depend on the reaction
medium and process conditions. Herein, we will theoretically study SEAr intermediates in solvent
and zeolite environments. Reactivity will be studied by an ingenious coupling of conceptual
reactivity descriptors and construction of free energy profiles by means of advanced molecular
dynamics methods. Such techniques allow following chemical transformations in-situ, thus closely
mimicking experimental conditions. Complementary qualitative insights into reactivity will be
obtained with a conceptual density functional theory approach. The combined approach will yield
insights into governing reaction mechanisms and its dependency on the molecular environment and
operating conditions. The theoretical work will be performed in close synergy with a prominent
experimental partner, who recently spectroscopically identified the Wheland intermediate for
benzene ethylation in zeolites. The outcome of the project will provide a general approach to
unravel chemical reactivity in complex reaction environments.