By B3LYP/6-311++G(df,p) quantum-chemical method complete thermodynamic characteristics (enthalpies, entropies, total Gibbs energies, equilibrium constants) were evaluated for separate stages of the thermal decomposition of dimethyl 4,4'-methylenebis(4,1-phenylene)dicarbamate with the formation of diphenylmethandiisocyanate and methanol. The temperature ranges providing the equilibrium yield of diphenylmethandiisocyanate equal to 95–99% were estimated. Principal possibility of obtaining practically pure diphenylmethandiisocyanate while decomposing the dimethyl 4,4'-methylenebis(4,1-phenylene)dicarbamate due to the regulation of temperature of the process was shown.
карбаматы, изоцианаты, carbamates, isocyanates
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