Affiliation:
1. Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina, Viale F. Stagno D’Alcontres,
31 Vill. S. Agata Messina, Italy
Abstract
Abstract:
Rhodium catalysts for hydroformylation of aryl alkenes generally promote the
formation of branched aldehydes. Here, we have demonstrated that by using a single rhodium
catalyst containing a diphosphoramidite ligand derived from BINOL, it is possible to
achieve the inversion of regioselectivity in the hydroformylation of aryl alkenes simply by
reducing the syngas pressure or, alternatively, increasing the reaction temperature. Indeed,
the hydroformylation of styrene carried out at 20 bar and 50°C resulted in 72% of 2-
phenylpropanal, while at atmospheric pressure, 71% of 3-phenylpropanal was obtained. A
similar linear selectivity (72-74%) was observed when the hydroformylation of styrene, pmethylstyrene,
and p-methoxystyrene was performed at 10 bar and higher temperature
(80°C). The regioselectivity of the hydroformylation of trans-β-methylstyrene under mild
conditions (80°C, 10-20 bar) was also strongly influenced by the syngas pressure. The results of this study show
that it is possible to reverse the selectivity of aryl alkenes hydroformylation with a single catalyst by simply exploring
the reaction conditions. In this paper, we have shown that the inversion of the regioselectivity in the hydroformylation
of aryl alkenes can be achieved using a single rhodium catalyst containing a BINOL-derived
diphosphoramidite ligand by reducing the syngas pressure or, alternatively, increasing the reaction temperature.
Publisher
Bentham Science Publishers Ltd.