Synthesis of organic carbonates through nonphosgene routes is a thrust area of research, because of future potential use of organic carbonates as fuels. Transesterification of propylene carbonate (PC) using alcohols is a green route for organic carbonate synthesis. The present study investigates the use of PC, along with ethanol, for the catalytic synthesis of diethyl carbonate (DEC) using Mg-La catalysts. First, thermodynamic study has been performed for the synthesis of DEC from PC. The Benson group contribution and the Rozicka-Domalski model method were used to estimate standard heat of formation of some components and the coefficient of heat capacity (C-p) with temperature. The reaction was found to be mildly endothermic. Mg-La has been synthesized using precipitation method using various Mg/La molar ratios (0.5, 1, 2, 2.5, and 4). Mg-La2 was determined to be the catalyst that performed best among all the synthesized catalysts. The effect of precipitants on the physiochemical properties of the catalyst was also studied. The basicity was determined to be in high correlation with PC conversion; 46% DEC yield was obtained with 63.6% and 72.3% selectivity at 150 degrees C in 4 h using 1.3% catalyst. Equilibrium thermodynamics study of the reaction was also studied by calculating the equilibrium constant on the basis of both the number of moles of components and activity coefficients.