TDI (toluene diiocyanate) serves as a hardener in the manufacture of composite propellant. The manufacture of TDI steps are long enough, one of which is the formation of toluene dicarbamate which will be decomposed to form TDI. To make toluene dicarbamate own needs an organic carbonate compound as the reactan. Then, the study of organic carbonates need to be done to choose the suitable one of the process and easy in manufacture and availability of the basic materials. Study results obtained the manufacture of organic carbonates (dimethyl carbonate) with the basic materials of methanol and urea. Reactions were carried out in autoclave reactor equipped with magnetic stirrer and reflux column to separate ammonia. Reaction run at T = 180ºC, with a catalyst of CaO-Carbon alloys.