Valorisation of Mixtures of Linear Alkenes using Cobalt-Mediated Isomerisation and Hydroformylation Chemistries

Active catalysts derived from cobalt and the Xantphos ligand were synthesised, characterised and tested in the

hydroformylation of pure linear alkenes or their mixtures. The preformed complex [Co2(CO)6(Xantphos)] showed similar

reactivity and selectivity towards aldehydes as the active catalyst formed in situ from equimolar amounts of [Co2(CO)8] and

Xantphos. In the case of oct-1-ene, the linear aldehyde was obtained with good chemo- and regio-selectivity (linear to

branched ratio was up to 75:25). For all octene isomers, tandem isomerisation-hydroformylation processes took place.

Regioselectivities for all the studied octene isomers remained practically constant, independently of the position or

geometry of the CC double bond in the starting material. Moreover, by-products were formed in similarly small amounts

for all the octene isomers. We also demonstrated that this chemistry is an interesting strategy for valorising mixtures of

linear hexenes, heptenes or octenes by transforming the initial mixture into one major aldehyde (addition of a CHO group

to the C1 carbon of the alkene skeleton, up to 73% selectivity). Moreover, these mixtures of alkenes were hydroformylated

with low final amounts of non-hydroformylated alkenes, hydrogenated alkenes and alcohols.