Structure, Dynamics, Interaction Energies, and Liquid/Vapor Equilibria in Dialkylcarbonates.

Abstract

We discuss a systematic investigation into the liquid/vapor equilibria and interfacial properties of a homologous series of dialkyl carbonates (DACs), specifically dimethyl carbonate (D1C), diethyl carbonate (D2C), dipropyl carbonate (D3C), and dibutyl carbonate (D4C), using classical molecular dynamics simulations (CMDs). Simulations were performed over a temperature range of 350-450 K to elucidate the impact of alkyl chain length on the thermodynamic, liquid/vapor, and transport properties. Our results demonstrate that saturated vapor pressures decrease uniformly with increasing alkyl chain length, ranging from 6.0 bar for D1C to 0.56 bar for D4C at 450 K. Smooth adjustment of DAC volatility is useful to offer the most suitable solvent and conditions. Specific liquid densities decreased with both increasing temperature and chain length, with D1C exhibiting the highest thermal expansivity, 2.2 × 10-3 1/K. Translational dynamics reveal a strong temperature dependence and a systematic decrease in molecular mobility as the chain length grows. Electrostatic interactions dominate the structural and dynamical properties of DACs, thanks to large partial charges on the headgroup. The rendered results are of fundamental importance to understand DACs at elevated temperatures.