Hydroformylation of 1-octene using rhodium-1,3-R 2-3,4,5,6-tetrahydropyrimidin-2-ylidenes (R = 2-Pr, mesityl)

Abstract

Four different Rh (I) complexes, i.e. [RhBr(1,3-di(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(COD)] ( 1), [RhCl(1,3-di(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(COD)] ( 2), [RhBr(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(COD)] ( 3) and [RhCl(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(COD)] ( 4), (COD = η 4-1,5-cyclooctadiene, mesityl = 2,4,6-trimethylphenyl), were used in the hydroformylation of 1-octene. All compounds were active in the hydroformylation, showing a time dependant n: iso ratio, indicative for olefin isomerization. This olefin isomerization was also monitored as a function of time. TOFs for hydroformylation obtained with 1 and 2 were around 500, those achieved with 3 and 4 around 1500 h −1.