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The reactivity of a series of N-arylacetamides, R--C(sub 6)H(sub 4)--NHCOCH(sub 3), with respect the alkaline hydrolysis reaction is studied. The electrostatic potential at the nuclei is recommended as an accurate local reactivity index.

The feasibility of molecular electrostatic potential measurements at atomic sites as reactivity descriptor for the mechanism of hydrogen bonding is evaluated for a range of complexes consisting of acetylene and diacetylene derivatives as proton donors and ammonia as an acceptor. A distinct linear relation between the molecular electrostatic potential with the energy of hydrogen-bond formation is observed.

Research has been conducted on the amide carbon-nitrogen bond. The role of the polar substituents in the internal rotation barrier around this bond has been investigated via the use of the density functional theory and the linear dependence between the rotation barriers and frequency shifts has been discovered.

The hydrogen bonding between hydrogen fluoride and a series of simple nitrile and carbonyl compounds was investigated using ab initio molecular calculations at the HF/6-31+G(d,p) level. The results can be explained in terms of the variation of the molecular electrostatic potential at the nitrile nitrogen for the series of nitrile compounds and at the carbonyl oxygen for the series of carbonyl compounds. A dependence between the calculated molecular electrostatic potential and interaction energy that unifies the two series was also observed.

A study was conducted relating to research on the intermolecular phenomenon of hydrogen bonding in terms of the structural and electronic properties of proton donor and acceptor molecules. The experiment aimed primarily to analyze the trends of the changes in the energy of hydrogen-bond formation in aliphatic carbonyl derivatives and to explain the results in terms of properties of either the complex or the isolated molecule. Results of the study are discussed.

A newly develop theoretical construct of electrophile affinity (E[alpha]) based on computed energies of arenium ion formation which rationalized the substrate reactivity and regioselectivity of [S.sub.E]Ar bromination of three sets of available experimental arene data is presented. The computed E[alpha] parameters correlated very well with the partial rate factors for 18 regiospecific brominations of benzene and various methyl benzenes.

The literature data for the partial rate factors and (ln) for [S.sub.E]Ar processes are compared to theoretical reactivity parameters to rationalize the reactivity and regioselectivity of the electrophilic chlorination, nitration, and alkylation of benzene derivatives. The observed variations of electron density at the different arene ring positions and the experimental partial rate factors for the chlorination and nitration reactions are attributed to strong steric influences on the reaction rates for substitutions involving the bulky benzyl moiety.

The [S.sub.N]2 identity exchange reactions of the fluoride ion with benzyl fluoride and 10 para-substituted derivatives are examined by ab initio methods and density functional theory. The focal-point computations have validated the benzylic effect by establishing [S.sub.N]2 barriers for ([F.sup.-], [Cl.sup.-]) identity exchange in ([C.sub.][H.sub.5]C[H.sub.2]F, [C.sub.6][H.sub.5]C[H.sub.2]Cl) that are lower than those of (C[H.sub.3]F, C[H.sub.3]Cl).

A study was conducted to examine the kinetics of the aminolysis process for a series of seven parasubstituted phenyl acetate derivatives containing both electron-withdrawing and electron-donating groups. The electrostatic potentials observed at the carbon atom of the carbonyl reaction center provide insight into both the theoretical barrier heights and experimental rate constants.

The relative stabilities of the five conformers of allyl amine, a medium-size aliphatic molecule, are estimated at several levels of theory. The results suggest that satisfactory predictions of the conformer energetics of allyl amine can be achieved only by theoretical methods.

Density functional theory (DFT) computations are carried out for a series of 15 monosubstituted benzene derivatives in order to study dependencies between electronic structure parameters and experimental reactivity constants. The results have emphasized the reliability of electrostatic potential values (EPN) as a local reactivity descriptor and have indicated that the relative values of the [sigma.sup.D] constants are predominantly determined by intramolecular influences.

The possible mechanistic pathways for the reaction of methyl benzoate with ammonia are examined by density functional and ab initio methods and transition state structures and energies are determined for concerted and neutral stepwise mechanisms. Theoretical results show that the two possible pathways have similar activation energies and predictions reveal that the catalytic process results in energy savings and a general-base-catalyzed neutral stepwise mechanism is favorable.

The variations of barrier heights for rotation around the amide C-N bond in para-substituted thioacetanilides was studied in a comparative context with data for a series of acetanilides by applying density functional theory. The results obtained were consistent with the views for a classical amide resonance as being the origin of higher rotational barriers in thioamides than in amides.

Research has been conducted on 2-benzoxazolinone. The authors have investigated the mechanisms of ring-opening reaction of this compound upon aminolysis with methylamine via the use of quantum mechanical methods, and have discussed the results.

Research has been conducted on ester aminolysis. The possible mechanistic pathways of ester aminolysis reaction have been investigated, and the results are reported.

Abstract: The potential energy surfaces for the SN2 reactions of allyl and propyl chlorides with 21 anionic and neutral nucleophiles was studied by using ωB97X‐D/6‐311++G(3df,2pd) computations. The “allylic effect” on SN2 barriers was observed for all reactions, and compared with propyl substrates, the energy barriers differed by −0.2 to −4.5 kcal mol−1 in the gas phase. Strong correlations of the SN2 net activation barriers with cation affinities, proton affinities, and electrostatic potentials at nuclei demonstrated the powerful influence of electrostatic interactions on these reactions. For the reactions of anionic (but not neutral) nucleophiles with allyl chloride, some of the incoming negative charge (0.2–18 %) migrated into the carbon chains, which would provide secondary stabilization of the SN2 transition states. Activation strain analysis provided additional insight into the allylic effect by showing that the energy of geometric distortion for the reactants to reach the SN2 transition state was smaller for each allylic reaction than for its propyl analogue. In many cases, the interaction energies between the substrate and nucleophile in this analysis were more favorable for propyl chloride reactions, but this compensation did not overcome the predominant strain energy effect. [ABSTRACT FROM AUTHOR]

Density functional theory computations with the B3LYP/6‐311++G(2df,2p) method and IR spectroscopy are employed in investigating the properties of twenty π‐hydrogen bonded complexes between substituted phenols and hexamethylbenzene. All complexes possess T‐shaped structures. The methyl hyperconjugative effects on interactions energies and OH stretching frequencies are estimated via comparisons with previously reported theoretical and experimental results for analogous phenol complexes with benzene. The theoretical computations provide excellent quantitative predictions of the OH stretching frequency shifts (ΔνOH) resulting from the hydrogen bonding. The ΔνOH shifts in the hexamethylbenzene complexes are approximately twice as large as the corresponding shifts for the benzene complexes. Hirshfeld charges, electrostatic potential at nuclei values, and molecular electrostatic potential maps are employed in gaining insights into the mechanisms of methyl hyperconjugative effects on complex formation. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]