Specific features of physical chemistry and electronic structure of lower dicarboxylic acids

Abstract

The static and complex dielectric permittivities and dc electrical conductivities of solid oxalic, malonic, and succinic acids were measured. The relaxation times of single crystal blocks (3–5 days) and mean relaxation frequencies of molecules and low-molecular-weight associates of oxalic acid dihydrate (5 MHz) and malonic acid (160 kHz) at 19°C were estimated. Aqueous oxalic acid can absorb electromagnetic energy owing to the presence of solvated electrons and holes. The electrical conductivity of this acid is protonic, and that of the anhydrous acids, electronic; the electron-hole pairs are mainly generated in these acids by lattice vibrations. The applied alternating electric field caused desorption of active gases from the acids. In some experiments with malonic acid, fast isothermal rearrangements of hydrogen bond networks and avalanche ionization of molecules were observed at a slight increase in temperature. The diagrams of charge distribution in the free acid molecules were constructed on the basis of the previous dipole moment measurements and IR data.