HYDROFORMYLATION OF Z-2-BUTENE WITH THE PTCL2(COD)/SNCL2/L CATALYTIC-SYSTEM .3. THE EFFECT OF THE PHOSPHORUS LIGAND-L

In a study on the hydroformylation of the internal olefln, 2-butene, with the catalytic system PtCl2(cod)/SnCl2 in the presence of a phosphorus ligand L, the ligand has been varied in an attempt to achieve high selectivities with respect to the linear aldehyde, n-pentanal. Forty ligands were examined and the catalytic results are discussed in terms of steric and electronic parameters. When the ligand is not too bulky, the reactivity is determined solely by the electronic parameter. Very promising results were obtained with aryl phosphites as the phosphorus ligands; selectivities in n-pentanal of 65-75% have been achieved, along with a high activity of the catalytic system. The proportion of hydrogenation is relatively low (5-10%). A considerable disadvantage with this catalytic system is the instability of phosphite ligands under the reaction conditions; however, use of cyclic phosphites has been found to enhance the stability of the system. © 1990.