Influence of the addition of thiophenes on the catalytic activity of the rhodium binuclear complex [Rh(CO)(μ-Pz)(TPPTS)] 2 during the biphasic hydroformylation of 1-hexene

Abstract

The preactivation of the binuclear complex [Rh(CO)(μ-Pz)(TPPTS)] 2, TPPTS = tris- meta-sulfonatophenylphosphine and Pz = pyrazolate ligand, during the two-phase catalytic hydroformylation of 1-hexene was studied under mild reaction conditions [1746.9 kPa of syngas (CO/H 2 = 1:1), S/C = 200, R.P.M. = 700, T = 343 K, t = 3 h], under which it was confirmed the formation of mononuclear active species responsible of the olefin hydroformylation. The presence of compounds such as thiophene and benzothiophene up to 2500 ppm did not interfere with the evolution of the reaction, confirming that the active specie is resistant to sulphur. It was found that under anaerobic conditions, the catalytic activity remains almost constant after four consecutive recycles, leading to the production of aldehydes and the corresponding isomerization products, cis- and trans-2-hexene.