Catalytic properties of Fe(acac)3 and Cu(acac)2 in the formation of urethane from a diisocyanate derivative and EtOH

The catalytic performance of metal–β-diketone complexes Fe(acac)3 and Cu(acac)2 is described for urethane formation reactions from hexamethylene diisocyanate (HDI) and ethanol. This is a model reaction for the synthesis of polyurethane resin that takes place during the application of reactive paint. The best results are obtained for the reaction between HDI and EtOH catalysed by the Fe(acac)3 complex. The diurethane adduct selectivity is 90% with a turnover rate of 74 h−1. Similar experiments conducted with a commercial catalyst, dibutyltin dilaurate (DBTDL), show that for the same reaction conditions no diurethane adduct is formed and that the turnover rate is lower (29 h−1).