D. A. Kornilov

Atmospheric and high pressure ene reaction of norbornene with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione

Thermodynamic and activation parameters (enthalpy, entropy, and volume) have been determined from the pressure and temperature dependences of the rate of the reaction of norbornene with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione in toluene, which is accompanied by Wagner-Meerwein rearrangement. The enthalpy of the reaction in 1,2-dichloroethane has been determined by calorimetry. The obtained data correspond to a weakly polar transition state.

Ene reaction of 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione with dicyclopentadiene

The kinetics of the ene reaction of endo-dicyclopentadiene with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione in benzene, toluene, acetonitrile, 1,2-dichloroetane, and chloroform have been studied. The reaction volumes and enthalpies have been determined, and the activation volume in toluene has been calculated from the pressure kinetic data. The “anomalous” ratio ΔVcorr≠/ΔVr = 1.34 corresponds to a concerted cyclic transition state, though the addition product has acyclic structure.

Features of the Diels-Alder reaction between 9,10-diphenylanthracene and 4-phenyl-1,2,4-triazoline-3,5-dione

The Diels-Alder reaction between substituted anthracenes 1a−1j and 4-phenyl-1,2,4-triazoline-3,5 (2) is studied. In all cases except one, the reaction proceeds on the most active 9,10-atoms of substituted anthracenes. The orthogonality of the two phenyl groups at the 9,10-position of diene 1a is found to shield 9,10-reactive centers. No dienophiles with C=C bonds are shown to participate in the Diels-Alder reaction with 1a; however, the reaction 1a + 2 proceeds with the very active dienophile 2,4-phenyl-1,2,4-triazoline-3,5-dione. It is shown that attachment occurs on the less active but sterically accessible 1,4-reactive center of diene 1a. The structure of adduct 3a is proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The following parameters are obtained for reaction 1a + 2 ⇆ 3a in toluene at 25°C: Keq = 2120 M−1, ΔHf≠ = 58.6 kJ/mol, ΔSf≠ = −97 J/(mol K), ΔVf≠ = −17.2 cm3/mol, ΔHb≠ = 108.8 kJ/mol, ΔSb≠ = 7.3 J/(mol K), ΔVb≠ = −0.8 cm3/mol, ΔHr-n = −50.2 kJ/mol, ΔSr-n = −104.3 J/(mol K), ΔVr-n = −15.6 cm3/mol. It is concluded that the values of equilibrium constants of the reactions 1a−1j + 2 ⇆ 3a−3j vary within 4 × 101−1011 M−1.

Effect of pressure on the rate of the Diels-Alder reaction of diethyl azodicarboxylate with 9,10-dimethylanthracene

The enthalpy, entropy, and volume of activation and volume of the Diels-Alder reaction of diethyl azodicarboxylate with 9,10-dimethylanthracene in 1,2-dichloroethane have been determined. Possible factors responsible for the sharp difference between the volumes of activation and reaction are considered.

Studying the effect of high pressure on the cycloaddition reactions of maleic anhydride and substituted anthracenes

The kinetics (rate, activation, and volume) of the high-pressure (up to 2500 bar) Diels-Alder reactions of maleic anhydride with 9-phenylanthracene and 9,10-dimethylanthracene in toluene is investigated.

Kinetics and thermochemistry of [2π + 2σ + 2σ]-cycloaddition of quadricyclane to tetracyanoethylene

Kinetic data for the unusual [2π + 2σ + 2σ]-cycloaddition of quadricyclane to tetracyanoethylene in toluene have been obtained for the first time. The same reaction in 1,4-dioxane appears to be the most exothermic among known cycloaddition reactions. The entropy of activation and reaction volume differ only slightly from the corresponding parameters of conventional Diels–Alder reactions.

Changes in Permittivity and Density of Molecular Liquids under High Pressure

We collected and analyzed the density and permittivity of 57 nonpolar and dipolar molecular liquids at different temperatures (143 sets) and pressures (555 sets). No equation was found that could accurately predict the change to polar liquid permittivity by the change of its density in the range of the pressures and temperatures tested. Consequently, the influence of high hydrostatic pressure and temperature on liquid permittivity may be a more complicated process compared to density changes. The pressure and temperature coefficients of permittivity can be drastically larger than the pressure and temperature coefficients of density, indicating that pressure and particularly temperature significantly affect the structure of molecular liquids. These changes have less influence on the density change but can strongly affect the permittivity change. The clear relationship between the tangent and secant moduli of the permittivity curvatures under pressure for various molecular liquids at different temperatures was obtained, from which one can calculate the Tait equation coefficients from the experimental values of the pressure influence on the permittivity at ambient pressure.

[2π + 2π]-Cycloaddition of biadamantylidene to 4-phenyl-3 H -1,2,4-triazole-3,5(4 H )-dione. Effects of temperature, high pressure, and solvent

The effects of temperature, solvent nature, and high hydrostatic pressure on the rate of the reaction of biadamantylidene with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione have been estimated. Significant shielding of the C=C double bond in biadamantylidene is responsible for the high entropy and volume of activation. Quantitative yield of the reaction in the temperature range 25‒45°C is related to its exothermicity. The rate of the [2π + 2π]-cycloaddition unexpectedly weakly depends on the solvent polarity, which makes it radically different from the [2π + 2π]-reaction with tetracyanoethylene.

Enthalpy and entropy of activation and the heat effect of the ene reaction between 4-phenyl-1,2,4-triazoline-3,5-dione and 2,3-dimethyl-2-butene in solution

The rate of the fastest ene reaction between 4-phenyl-1,2,4-triazoline-3,5-dione (1) and 2,3-dimethyl-2-butene (2) is studied by means of stopped flow in solutions of benzene (k2 = 55.6 ± 0.5 and 90.5 ± 1.3 L mol−1 s−1 at 23.3 and 40°C) and 1,2-dichloroethane (335 ± 9 L mol−1 s−1 at 23.5°C). The enthalpy of reaction (−139.2 ± 0.6 kJ/mol in toluene and −150.2 ± 1.4 kJ/mol in 1,2-dichloroethane) and the enthalpy (20.0 ± 0.5 kJ/mol) and entropy (144 ± 2 J mol−1 K−1) of activation are determined. A clear correlation is observed between the reaction rate and ionization potential in a series of ene reactions of 4-phenyl-1,2,4-tri-azoline-3,5-dione with acyclic alkenes.

Ene reaction between 4-phenyl-1,2,4-triazoline-3,5-dione and hex-1-ene. The enthalpies, entropies, and volumes of activation and reaction in solution

The rates of an ene reaction between 4-phenyl-1,2,4-triazoline-3,5-dione and hex-1-ene were studied in a temperature range of 15–40 °C and in a pressure range of 1–2013 bar. The enthalpy of reaction in 1,2-dichloroethane (−158.2±1.0 kJ mol−1), the enthalpy (51.3±0.5 kJ mol−1), entropy (122±2 J mol−1 K−1), and volume of activation (−31.0±1.0 cm3 mol−1), and the volume of this reaction (−26.6±0.3 cm3 mol−1) were determined. The high exothermic effect of the reaction suggests its irreversibility.