V. N. Emel’yanenko

Thermodynamical properties of ε-caprolactone

The values of the combustion and enthalpies of formation for ε-caprolactone were determined by means of combustion calorimetry. The vapor pressures of lactone were measured in the range of 283–353 K, and the value of its enthalpy of vaporization was estimated by the transpiration method. Conformational analysis and calculations of the equilibrium structures, inertia moments, and sets of fundamental vibrations was performed by the B3LYP/6-311++G(3 df, 3 pd) quantum-chemical method. The total energies of the most stable lactone conformers were found and ΔfH(g) was estimated using the composite G3MP2 method. The set of fundamental vibrations for the most stable conformers of the compound was developed on the basis of the available experimental IR spectra and calculated vibration frequencies. The values of the thermodynamic properties of ε-caprolactone were determined in the ideal ga s state in the range of 0—1500 K. A set of reliable and interconsistent thermodynamic parameters for ε-caprolactone was created. Thermodynamic analysis for liquid-phase polymerization of s-caprolactone in the temperature range of 220—500 K was carried out.

Enthalpy of phase transitions of lactams

The transpiration method is used to measure the temperature dependences of the vapors pressures of azacyclobutan-2-one (I, CAS 930-21-2) azacyclohexan-2-one (II, CAS 675-20-7); azacyclooctan-2-one (III, CAS 673-66-5); azacyclononan-2-one (IV, CAS 935-30-8) and azacyclotridecan-2-one (V, CAS 947-04-6). Enthalpies of sublimation and vaporisation are determined. The temperatures and enthalpies of fusion of compounds (I, III-V) are found by means of differential scanning calorimetry. The dependences of the enthalpies of vaporisation of lactones, lactams, cycloalkanes, cycloalkanones on the size of a cycle are analyzed.

The thermodynamic properties of S-lactic acid

The enthalpies of combustion and formation of S-lactic acid at 298.15 K, ΔcHmo(cr.) = −1337.9 ± 0.8 and ΔfHmo(cr.) = −700.1 ± 0.9 kJ/mol, were determined by calorimetry. The temperature dependence of acid vapor pressure was studied by the transpiration method, and the enthalpy of its vaporization was obtained, ΔvapHo(298.15 K) = 69.1 ± 1.0 kJ/mol. The temperature and enthalpy of fusion, Tm (330.4 K) and ΔmHo(298.15 K) = 14.7 ± 0.2 kJ/mol, were determined by differential scanning calorimetry. The enthalpy of formation of the acid in the gas phase was obtained. Ab initio methods were used to perform a conformational analysis of the acid, calculate fundamental vibration frequencies, moments of inertia, and total and relative energies of the stablest conformers. Thermodynamic properties were calculated in the ideal gas state over the temperature range 0–1500 K. A thermodynamic analysis of mutual transformation processes (the formation of SS- and RS(meso)-lactides from S-lactic acid and the racemization of these lactides) and the formation of poly-(RS)-lactide from S-lactic acid and SS- and RS(meso)-lactides was performed.

The thermodynamic properties of delta-lactones

The enthalpies of formation of δ-hexanolactone and δ-nonanolactone were determined by combustion calorimetry. Conformational analysis and quantum-chemical calculations of equilibrium structures, fundamental vibrations, moments of inertia, and total energies were performed for δ-pentanolactone (I), δ-hexanolactone (II), and δ-nonanolactone (III) by the B3LYP/6-311G(d,p), B3LYP/6-311++G(d,p), and G3MP2 methods. The experimental IR spectra and calculated vibrational frequencies were used to suggest the assignment of vibrational frequencies of stable conformations. The thermodynamic properties of I–III in the ideal gas state were determined over the temperature range 0–1500 K. A thermodynamic analysis of mutual isomerization in the gas and liquid phases over the temperature range 298.15–900 K and liquid-phase polymerization of γ- and δ-pentanolactones and 4-pentenoic acid over the temperature range 298.15–500 K was performed.

The thermodynamic characteristics of 15-pentadecanolide and 16-hexadecanolide

Combustion calorimetry was used to determine the enthalpies of formation of 15-pentadecanolide (I) and 16-hexadecanolide (II). The temperature dependences of vapor pressure of lactones and the enthalpies of vaporization were determined by the transpiration method. Differential scanning calorimetry measurements were performed to find the temperatures and enthalpies of fusion of lactones. Conformational analysis and quantum-chemical calculations of the structural, vibrational, and energy characteristics of stable conformers of I were performed. The molecular and spectral data were used to calculate the thermodynamic properties of I in the ideal gas state. An explanation was suggested of the special features of changes in the enthalpies of vaporization in the series of unsubstituted lactones as the size of their rings increased.

The thermodynamic properties of alkylated γ-lactones

The enthalpies of formation of γ-pentanolactone (I), γ-hexanolactone (II), and γ-nonanolactone (III) were determined by combustion calorimetry. The enthalpies of vaporization of these lactones were measured by the transfer method. Conformational analysis was performed and equilibrium structures, sets of fundamental vibrations, moments of inertia, and total energies of the stablest conformers of I, II, and III were calculated by the B3LYP/6-311G(d,p), G3MP2, and CBS-QB3 methods. The experimental IR spectra and calculated vibrational frequencies were used to obtain sets of fundamental vibrations of the stablest conformations. The thermodynamic properties of I–III in the ideal gas state were determined over the temperature range 0–1500 K. Additive and quantum-chemical methods were applied to estimate the ΔfHo(g) values of a number of γ-lactones. Composite quantum-chemical methods were used to obtain the energies of monomethyl γ-butyrolactones and estimate their relative stability depending on the position of the methyl substituent in the ring.

Thermodynamic properties of glycolic acid and glycolide

The values of combustion and formation enthalpy for glycolic acid (I) and glycolide (II) were determined by calorimetry. The temperature dependence of vapor pressures of I and II was obtained using the transpiration method, and the sublimation enthalpies were obtained. The enthalpy of melting of I was found by differential scanning calorimetry. Stable conformers were determined by the ab initio (DFT) method, and combinations of the fundamental oscillations and inertia momenta of I and II conformers were calculated. The full and relative energies of the compounds most stable conformers were found by a composite G3MP2 method, and the enthalpies of formation of I and II in the gaseous state were estimated. The values of the thermodynamic properties in the ideal gas state were determined over the range of 0–1500 K. A thermodynamic analysis was performed for the process of preparation of II from I and the formation of polyglycolide (III) from I and II.

The thermodynamic properties of DL- and L-lactides

The enthalpies of formation of DL-lactide and L-lactide, cyclic esters of lactic acid, were determined by combustion calorimetry. The transfer method was used to measure their vapor pressures and obtain the enthalpies of sublimation. A conformational analysis of lactides was performed, and the most stable conformations were determined. The equilibrium structures of lactides, sets of fundamental vibrations, moments of inertia, and total energies of the most stable conformers were calculated quantum-chemically at the B3LYP/6-311++G(3df,3pd) level. The G3MP2 composite method was used to estimate the enthalpies of formation of lactides in the gas phase. The thermodynamic properties of lactides in the ideal gas state were calculated over the temperature range 100–1500 K.

Enthalpies of formation of lactams

Combustion calorimetry is used to measure the enthalpies of combustion and formation of azacyclooctan-2-one (I), azacyclononan-2-one (II), and azacyclotridecan-2-one (III) in the crystalline, liquid, and gaseous states. Conformational analysis is conducted, and quantum chemical calculations of the compounds’ enthalpies of formation in the gas phase for conformers corresponding to the global minima are performed. The experimental findings and published data are used to determine mutually congruent combinations of enthalpy parameters for a number of nonsubstituted lactams. The strain energies are estimated. Trends in their changes are considered for the series of cycloalkanes and lactams.

The thermodynamic properties of 1,4-dioxane-2,6-dione

The enthalpies of combustion and formation of 1,4-dioxane-2,6-dione were determined by combustion calorimetry. The transpiration method was used to obtain the temperature dependence of compound vapor pressures and the enthalpies of sublimation and vaporization. Differential scanning calorimetry was used to measure the enthalpy of fusion. Quantum-chemical calculations of the geometric, vibrational, and energy characteristics of the compound were performed, and the enthalpy of formation of the compound in the gas phase was estimated. Statistical thermodynamics methods were used to determine the thermodynamic properties of the compound in the ideal gas state over the temperature range 0–1500 K. Strain energies of some representatives of six-membered cyclic compounds were estimated.