Abstract
A variety of value added bulk and fine chemicals are available via transition metal catalysed carbonylation technology. The development of phosphine ligands plays a vital role in transition metal catalysis and provides important innovations in academia and industrial research. An excellent example is the Alpha process developed and commercialised by Lucite (now Mitsubishi Rayon Co, Japan). The industrial process employs 1,2-bis-[(di-tertbutylphosphino) methyl)benzene (dtbpx) in the palladium mediated carbonylation of ethylene to produce methyl propionate is a key precursor to acrylic monomer (methyl methacrylate) for the production of poly methyl methacrylate (PMMA). Another example in the academia environment is the use of Palladium complexes of diadamantylbutylphosphine (Pd-cataCXium® A) catalyst in the carbonylative activation of C–X Bonds of aryl and heteroaryl halides to produce carboxylic acid esters derivatives. Although a number of phosphine-based catalysts are known for carbonylation reactions, there is however a desire to develop novel catalysts that also afford high selectivity of the much-desired products. In this context, seven (7) ortho-aniline derived aminophosphine ligands were synthesised from ortho-iodoaniline by double phosphinylation involving first the P-C bond formation (cross-coupling) followed by the condensation of a chlorophosphine with an amine to introduce the P-N bond. The synthesised phosphine ligands were evaluated in the palladium catalysed carbonylation reactions of olefins and aryl halides. Of the prepared ligands, novel ligands 1,1-di-tert-butyl-N-(2-(diphenylphosphaneyl)phenyl)phosphanamine (ligand H) and 1,1-di-tert-butyl-N-(2-(dicyclohexylphosphaneyl)phenyl)phosphanamine (ligand J)were found to be active for the methoxycarbonylation of 1-octene. This study also investigated various reaction parameters in order to gain a better understanding of their influence on the catalytic performance. The results clearly demonstrated that the steric bulk of the ligand is crucial for the catalytic performance in terms of conversion and selectivity towards the desired linear ester product...
M.Sc. (Chemistry)