Global Kinetics and Spectral Modeling of -Methoxyphenyl Azide Photooxidation.

The kinetics of photooxidation of -methoxyphenyl azide was studied by flash photolysis with spectrophotometric detection of the absorption of active intermediates in an aerated acetonitrile solution at 295 K. The holistic set of experimental data including the consumption of - isomers of -methoxyphenyl nitroso oxide and the accumulation of photooxidation products (2,4)-4-methoxy-6-oxo-hexa-2,4-diene-nitrile oxide and bis--methoxy-azobenzene monitored via the changes in the optical density of the solution in the wavelength range of 300-500 nm was treated to obtain the most complete information about the system under study. Flash photolysis of results in the formation of the corresponding triplet nitrene, which either recombines to azobenzene with a rate constant 2 = (8.

BEP-Like Correction of Nonequilibrium Thermodynamic Parameters of the Solvent-Assisted Reactions: The DFT and Study of Hydration, Peroxidation, and Enolization of Acetone and 1,1,1-Trifluoroacetone in Aqueous Solutions.

The mechanisms of enolization and reactions of nucleophilic addition to carbonyl compounds were analyzed by density functional theory (DFT) (PBE1PBE) and (DLPNO-CCSD(T)) level of theory using the interaction of water and hydrogen peroxide with acetone and 1,1,1-trifluoroacetone (TFA) as the reference reactions. The transition states of the studied reactions were localized within the integrated approach that includes both the dielectric continuum theory (polarizable continuum model (PCM)) and the cyclic or two-cluster explicit solvation models. The considered models provide proton transfer in the enolization, hydration, and peroxidation reactions by the Grotthuss mechanism.

The substituent effects on the [3+2] cycloaddition of nitrile oxides generated by photooxidation of arylazides to acetonitrile.

The DFT approach in M06L/6-311 + G(d,p) approximation was used to study the transformation of unsaturated nitrile oxides (RCNO), which were generated by photooxidation of the corresponding aromatic azide, to oxadiazoles via [3 + 2]cyclization with acetonitrile. It was found that the cycloaddition activation enthalpy was within 60-93 kJ/mol, depending on the structure of the nitrile oxide. A significant mesomeric effect of the substituent and its position in the conjugated molecular system on the activation barrier of the reaction studied was identified.

Nature of Lewis Base Catalysis of 1,3-Dipolar Cycloaddition of Methyl Diazoacetate to Methyl Acrylate; NMR Kinetic Spectroscopy and DFT Study.

The effect of Lewis base (LB) in the domino reaction between methyl diazoacetate and methyl acrylate has been studied. This domino process is initialized by a [3+2]-cycloaddition reaction to generate 3H-pyrazoline followed by a subsequent 1,3-H shift reaction forming 1H-pyrazoline as the more stable isomer. The rate of the first step is not sensitive to the presence of LBs (THF, Py, DMAP, DBU, and triphenylphosphine) as it was evidenced by kinetic nuclear magnetic resonance spectroscopy and quantum chemical modeling.