Аннотации:
© 2017 Elsevier Ltd In the present work, the temperature dependence of heat capacity of vitamin B8 (myo-inositol) has been measured for the first time over the range from 8 K to 340 K by precision adiabatic vacuum calorimetry. Based on the experimental data, the thermodynamic functions of the vitamin B8, namely, the heat capacity, enthalpy H°(T)–H°(0), entropy S°(T)–S°(0) and Gibbs function G°(T)–H°(0) have been determined for the range from T → 0 K to 340 K. The value of the fractal dimension D in the function of multifractal generalization of Debye's theory of the heat capacity of solids was estimated and the character of heterodynamics of structure was detected. The enthalpy of combustion (−2747.0 ± 2.1) kJ·mol−1 of the vitamin B8 was measured for the first time using high-precision combustion calorimeter. The standard molar enthalpy of formation in the crystalline state (−1329.3 ± 2.3) kJ·mol−1 of B8 at 298.15 K was derived from the combustion experiments. Using combination of the adiabatic and combustion calorimetry results the thermodynamic functions of formation of the myo-inositol at T = 298.15 K and p = 0.1 MPa have been calculated. The low-temperature X-ray diffraction was used for the determination of coefficients of thermal expansion.
