Kinetics on Palladium Catalyzed Carbonylation of lodobenzene under Carbon Monoxide Pressure

Abstract

The carbonylation of iodobenzene has been studied kinetically in the presence of catalytic amount of palladium chloride. ln the reaetion of iodobenzene and carbon monoxide under pressure in a methanol solution, the addition of a suMcient amount of pyridine makes the catalyst soluble to form a homogeneous solution, and facilitates the methyl benzoate formation under mild conditions.
Based on the assumption thatthe reaction involves methoxy and carbomethoxy-palladium cQmplexes, following rate equation has been derived
(CH80)PdC1(py)2+CO rl; (CH300C)PdCl(py)2
(cH, OOc)PdCl (py)d phl 13 L. PhCO2CHs + PdCII(py)2
kik2HPee(PdC12)o((Phl)e (Ester))
(1 kd(PdC12)gt) (k-I kiHPco k2((Phl)g (Ester))) kd(PdC12)c
Where kd-is rate constant of deactivation. This equation is in reasonabl. e, qgreement with the experimental results. The rate constants and the overall activation energyt have been determined to be kiH=8.16 10m2 a/tmpti, minFi, (H; Henry constant of CO), k.. i=O.185 min-i, k2=7.64 mol-i, 1, min-i, kd=31.7mol-i, 1, min-i at 1000C and E. =20.9kcal, mol-i, respectively.