In this work, we investigated the mechanism and the regioselectivity of the nitration reaction of 3-isopropyl-1,6-dimethyl-naphthalene, ar-himachalene and 4-nitroar-himachalene within the MEDT. These ...nitration reactions evolved through a two-step mechanism. Analysis of the Parr functions and analysis of the relative energies associated with the competitive reaction paths shows that the nitration reactions of ar-himachalene, 2-nitroar-himachalene and 3-isopropyl-1,6-dimethyl-naphthalene are highly regioselective, in clear agreement with the experimental outcomes.
This theoretical study, performed using density functional theory at the B3LYP/6-311+G(d,p) level, shows that the most likely route to obtain 3-phenyl1,2,4oxadiazolo4,5-
a
benzimidazole from the ...reaction of 2-chlorobenzimidazole with benzonitrile oxide implies the presence of anionic species. A concerted 3+2 cycloaddition reaction on the imidoyl group of 2-chlorobenzimidazole is not possible. The presence of a polar protic solvent (MeOH) favors the reaction. The analysis of the Wiberg indices shows that the transition states are earlier in MeOH than in THF or gas phase. Finally, topological analysis of the electron localization function indicates that the formation of the N4–C3 and C5–O bonds and the breaking of the C5–Cl bond in the preparation of 3-phenyl1,2,4oxadiazolo4,5-
a
benzimidazole are marked for each by the presence of an asynaptic basin V(Asyn) and proceed through tetrahedral intermediates, indicating the nonconcerted nature of the mechanism. These results are in good agreement with the experimental results.
Context
The controlled slow evaporation process conducted at room temperature has produced a novel hybrid material denoted as (2-hydroxyethyl) trimethylammonium dihydrogen phosphate 2-HDETDHP (C
5
H
...14
NO
+
, H
2
PO
4
−
), synthesized through the solution growth method. X-ray crystallography analysis reveals a triclinic structure with a filling rate of P and a Z value of 2. This hybrid material displays noteworthy absorption characteristics in the middle and far ultraviolet regions. UV-visible spectroscopy further establishes its transparency in the visible and near-visible ultraviolet domains. FT-IR spectroscopy examines various vibration modes, elucidating their relationships with the functional groups within the structure. Two- and three-dimensional fingerprint maps, coupled with three-dimensional crystal structures through Hirshfeld Surface Analysis, unveil the dominance of O•••H and H•••H interactions in the structure, comprising 49.40% and 50.40%, respectively. Fingerprint plots derived from the Hirshfeld surface assess the percentages of hydrogen bonding interactions, with 80.6% attributed to a fragment patch. The experiment of antimicrobial efficacy of a synthesized product, conducted in triplicate, demonstrated the synthesized product’s potential antimicrobial activity.
Methods
Hirshfeld surfaces are employed to investigate intermolecular hydrogen bonding, specifically within single phosphate groups. The molecular structure of 2-HDETDHP was refined using single-crystal X-ray analysis, while its optical characteristics were examined through UV-visible spectroscopy. FT-IR spectroscopy is employed for the assignment of molecular vibrations of functional groups in the affined structure. Quantum calculations were executed with the GAUSSIAN 09 software package at B3LYP/6-311G level of theory, to optimize the molecular geometries. The antimicrobial efficacy of a synthesized product was evaluated using the disc diffusion method against antibiotic-resistant
Candida albicans
,
Candida tropicalis
,
Aspergillus niger
,
Staphylococcus aureus
, and
Escherichia coli
. Microorganisms were cultured on nutrient agar, and inhibition zones were measured after incubation, with streptomycin and amphotericin as positive controls.
The 32CA cycloaddition reactions of the hydroxyparthenolide with nitrilimine have been studied using molecular electron density theory. The reactivity indices, activation and reaction energies are ...calculated at the B3LYP/6-31(d) level. The presence of two double bonds in hydroxyparthenolide gives six reaction pathways for this cycloaddition. The reaction proceeds via a one-step asynchronous mechanism with a nonpolar character, and an analysis of conceptual DFT indices explains the nonpolar character of this cycloaddition reaction. The calculations of the activation and reaction energies show that this cyclization reaction takes place on the C
1
=C
2
double bond, which indicates that this cycloaddition reaction is chemospecific and regiospecific in full conformity with the experimental results. The reorganization of electrons along the most preferred pathway of the 32CA cycloaddition reaction between hydroxyparthenolide and nitrilimine was investigated using topological analysis of the electron localization function (ELF). ELF analysis revealed that this reaction proceeds through a two-stage one-step mechanism.
Since the epidemic of COVID-19 was declared in Wuhan, Hubei Province of China, and other parts of the world, several studies have been carried out over several regions to observe the development of ...the epidemic, to predict its duration, and to estimate its final size, using complex models such as the SEIR model or the simpler ones such as the SIR model. These studies showed that the SIR model is much more efficient than the SEIR model; therefore, we are applying this model in the Kingdom of Morocco since the appearance of the first case on 2 March 2020, with the objective of predicting the final size of the epidemic.
The cycloaddition reactions (32CA) of acetonitrile N-oxide and 2,5-dimethyl-2H-1,2,3diazarsole
1
have been examined employing the molecular electron density theory through DFT calculations at the ...B3LYP/6-31G ++(d,p) computational level. Investigation of the relative energies related to the competitive
ortho
and
meta
reaction paths demonstrates a high chemo-, stereo- and regioselectivity for this 32CA reaction in clear conformity with the experimental results. The topological study of the electron localisation function of the certain points of the IRC associated with the construction of the As–C and C–O single bonds shows a zwitterionic-type structure. The 32CA reaction takes place via a two-stage one-step mechanism initialised with the formation of the As–C single bond.
In the current work, the chemical reactivity of some trivalent phosphorus derivatives R
2
PR
′
towards polyhaloalkanes CCl
3
POR ′ ′
2
was studied by the quantum method DFT/B3LYP/6-311G(d,p). The ...introduction of substituents for the trivalent phosphorus derivative and polyhaloalkane allowed us to have more information on these reactions. On the one hand, the calculation of reactivity indices derived from the DFT/B3LYP/6-311G(d,p) method and the gap
LUMO − HOMO
show that trivalent organophosphorus derivatives behave as nucleophiles, while polyhaloalkanes act as electrophiles. On the other hand, the calculation of the activation barrier and the determination of the free enthalpy variation prove that the kinetic and thermodynamic products of these reactions result from the nucleophilic attack of the phosphorus atom on the chlorine halogen. All these theoretical predictions are in very good agreement with the experimental results.
Context
3+2 cycloaddition processes between isoalantolactone (
ISALL
) and diazocyclopropane (
DCYP
), have been surveyed exercising the MEDT, reactivity indices, reactions, and activation energies, ...are computed. In an investigation of conceptual DFT indices,
DCYP
behaves as a nucleophile in this reaction, whereas
ISALL
acts as an electrophile. This cyclization is stereo-, chemo-, and regiospecific, as demonstrated by the activation and reaction energies, in clear agreement with the experiment’s results. The mechanism for this 3+2 cycloaddition is occurring in two steps, according to ELF analysis.
Methods
For the purposes of this investigation, all computations were performed using the Gaussian 09 program. The optimization was completed using Berny’s computational gradient optimization approach with the basis set 6-311G(d,p) and wB97XD functional. Frequency computations were utilized to characterize and locate stationary points where the transition phases have just one imaginary frequency and all frequencies for the reactants and products are positive. After evaluating the effect of dichloromethane (DCM) as a reaction solvent, the stationary point optimization was updated using the polarizable continuum model (PCM) developed by the Tomasi team. The electron localization function (ELF) has been examined within the context of topological investigations using Multiwfn software with a 0.05 grid step.
Graphical Abstract
Application of molecular electron density theory (MEDT) to investigate the 5+2 cycloaddition reaction between oxidopyrylium and ethervinylether, we discovered that oxidopyrylium is an electrophile ...and ethervinylether is a nucleophile by an examination of conceptual DFT indices. Analysis of energetical parameters shows clearly that this cycloaddition is both regio- and stereoselective, which is extremely consistent with the experience. Topological analysis of the electron localization function (ELF) has shown that this 5+2 cycloaddition is achieved by a two-step, single-step mechanism along the most favored route. Aside from that, docking outcomes show that the (
1
–
20
) oxabicyclo3.2.1octene derivatives have a significant anti-HIV potential.
PDF
