Catalytic carbonylation for the synthesis of chemical intermediates

Chemistry related to three catalytic carbonylation reactions is discussed. Synthesis of diphenylurea from nitrobenzene, aniline, and CO gives isolated yields above 98% at 100-120 degrees C and 15-60 bar of CO in the presence of a palladium (II) complex, PPh3 and NEt4Cl. Experimental evidence was provided to prove a new reaction stoichiometry and involvement of a carbamoyl intermediate. In carbonylation of HCHO over ion exchange resin catalysts, reaction temperature, time, pressure, and solvent were important variables to obtain high yields of methyl glycolate. Carbonylation of isobutylphenylethanol at 120 degrees C and 40 bar of CO in the presence of PdCl2-PPh3-HCl gives 98% yield of alpha-(4-isobutylphenyl) propionic acid (ibuprofen). Each catalyst component had a definite role that is indispensable for an efficient overall reaction.