posted on 2023-01-03, 17:45authored byMorad M. El-Hendawy, Ibtesam M. Desoky, Mahmoud M. A. Mohamed, Henry J. Curran
The current project aims to apply the virtues of minimalism
to
examine the catalytic ability of commercially organic compounds of
small chemical structures to catalyze the coupling reaction between
carbon dioxide and propylene oxide (PO) under mild conditions. The
proposed catalysts are pyridinium iodide (A), 2-hydroxypyridinium
iodide (B), and piperidinium iodide (C),
where their structure is based on cooperative acidic and nucleophilic
motifs. The quantum chemistry model, M062X-D3/def2-TZVP//M062X-D3/def2-SVPP,
was used to understand the reaction mechanism and the catalytic performance.
Since the coupling reaction was performed under excess PO, we proposed
that PO serves as a reactant and solvent. Therefore, calculations
were performed in gas and liquid phases for comparison. The findings
indicated that the rate-determining step depends on the chemical structure
of the catalyst and whether the phase is a gas or liquid phase. In
general, modeling in the liquid phase produces potential energy surfaces
of lower energy barriers. The noncovalent interactions reflect the
role of hydrogen bonding in controlling the kinetic behavior of the
coupling reaction. Based on the finding, catalyst A is
the best candidate for transforming CO2 into cyclic carbonates.