Deciphering the Curly Arrow Representation and Electron Flow for the 1,3-Dipolar Rearrangement between Acetonitrile Oxide and (1S,2R,4S)-2-Cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl Acetate Derivatives.

This study is focused on describing the molecular mechanism beyond the molecular picture provided by the evolution of molecular orbitals, valence bond structures along the reaction progress, or conceptual density functional theory. Using bonding evolution theory (BET) analysis, we have deciphered the mechanism of the 1,3-dipolar rearrangement between acetonitrile oxide and (1S,2R,4S)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl acetate derivatives. The BET study revealed that the formation of the C-C bond takes place via a usual sharing model before the O-C one that is also formed in the halogenated species through a not very usual sharing model. The mechanism includes depopulation of the electron density at the N-C triple bond and creation of the V(N) and V(C) monosynaptic basins, depopulation of the former C-C double bond with the creation of V(C,C) basins, and final formation of the V(O,C) basin associated with the O-C bond. The topological changes along the reaction pathway take place in a highly synchronous way. BET provides a convenient quantitative method for deriving curly arrows and electron flow representation to unravel molecular mechanisms.

Characterization of Akilbenza clay from Cameroon and its performance for the removal of copper(II) ions from aqueous solution.

Akilbenza clay (Akil) was characterized by XRD, FT-TIR, XRF, EDX, SEM, and N2 gas adsorption. The adsorption performance for Cu(II) ions by this clay was also studied. Akil is composed mainly of kaolinite with mica illite and quartz as minor minerals. The ATR-FTIR analysis shows Si-O-Al, Si-O, Al-O, Si-OH, and Al-OH as the main functional groups. SEM indicates that the clay particles are irregular in shape and size by supported BJH. Akil has a specific surface area of 45.62 m2/g with the presence of both mesopores and micropores. The average pore diameter is 19.4196 nm. XRF and EDX reveal that the clay is mainly composed of silica, aluminum, and iron with a Si/Al ratio of 1.41. For the adsorption performance of Cu(II) ions, a maximum quantity of 76 mg/g was recorded. Freundlich isotherm models best describe the adsorption processes at equilibrium. Kinetic studies revealed that the adsorption process was well explained with pseudo-second-order kinetic model. The value of the mean energy of adsorption from Temkin isotherm and the values from Elovich kinetic model suggest that the adsorption of Copper(II) ions on Akil is a combination between ion exchange and electrostatic attraction. The results obtained can be introduced into the database of knowledge on clay minerals with emphasis on their use for the removal of Cu(II) ions.

Intramolecular [3 + 2] Cycloaddition Reactions of Unsaturated Nitrile Oxides. A Study from the Perspective of Bond Evolution Theory (BET).

The reaction mechanism of the [3 + 2] intramolecular cycloaddition of 3,3-dimethyl-2-(prop-2-en-1-yloxy) and (prop-2-en-1-ylsulfanyl) nitrile oxides is analyzed using different DFT functionals with the 6-311++G(d,p) basis set. The activation and the reaction energies for the cis and trans pathways are evaluated at the DFT, MP2, and CCSD(T) levels of theory as well as their Gibbs free energy counterparts. It is shown that the trans regioisomers are both thermodynamic and kinetic compounds, in agreement with experimental outcomes. For a deeper understanding of the reaction mechanism, a BET analysis along the reaction channel ( trans and cis) has been carried out. This analysis reveals that the lone pair on the nitrogen atom is formed first, then the C-C bond, and finally the O-C one. The global mechanism is similar for the two compounds and for the two pathways even if some small differences are observed, for instance, in the values of the reaction coordinates of appeareance of the different basins.