1,2-bis-(ditertbutylphosphinomethyl)benzene in catalysis

Abstract

Different diphosphine ligands having the structure shown below have been studied for carbonylation and hydroformylation reactions. Depending on the substituent on the phosphorus atoms the electronic and steric properties can be tuned to direct the reaction towards the desired products. Palladium methoxycarbonylation of a large variety of unsaturated compounds has been attempted under very different conditions. The outcome of these reactions was the achievement of the linear products with a selectivity higher than 99.5 % under mild conditions of pressure and temperature. Chloroaromatic compounds have also been employed as substrates in methoxycarbonylation reactions. Unexpected results were observed since carbonylation was possible only when a strong electron withdrawing group was present. The origin of the many side products from these reactions has been elucidated. Rhodium hydroformylation was not as successful as palladium Methoxycarbonylation since relatively severe conditions had to be used to get good rates and good selectivity. In no case were there as good as those obtained in the carbonylation reactions. However, unusual factors, such as the presence of chlorine in the reaction media, have been found to influence either the conversion or the selectivity.