Process for the preparation of isophorone diisocyanate from isophorone dicarbamyl esters using highly selective SnO2 or CuO catalysts

摘要

Isophorone diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (IPDI) is prepared by liquid phase thermolysis of the corresponding bis-carbamic acid ester into the corresponding isocyanate and alcohol, respectively, in the presence of a highly selective metal oxide catalyst (SnO2 and/or CuO). Typically, the cracking reaction is carried out at a temperature from 225 DEG to 350 DEG C, at a pressure of from 20 to 50 mmHg. These catalysts give high IPDI yields with high conversions of the carbamic acid esters.