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

Abstract

<p>Active catalysts derived from cobalt and the Xantphos ligand were synthesised, characterised and tested in the</p><p>hydroformylation of pure linear alkenes or their mixtures. The preformed complex [Co2(CO)6(Xantphos)] showed similar</p><p>reactivity and selectivity towards aldehydes as the active catalyst formed in situ from equimolar amounts of [Co2(CO)8] and</p><p>Xantphos. In the case of oct-1-ene, the linear aldehyde was obtained with good chemo- and regio-selectivity (linear to</p><p>branched ratio was up to 75:25). For all octene isomers, tandem isomerisation-hydroformylation processes took place.</p><p>Regioselectivities for all the studied octene isomers remained practically constant, independently of the position or</p><p>geometry of the CC double bond in the starting material. Moreover, by-products were formed in similarly small amounts</p><p>for all the octene isomers. We also demonstrated that this chemistry is an interesting strategy for valorising mixtures of</p><p>linear hexenes, heptenes or octenes by transforming the initial mixture into one major aldehyde (addition of a CHO group</p><p>to the C1 carbon of the alkene skeleton, up to 73% selectivity). Moreover, these mixtures of alkenes were hydroformylated</p><p>with low final amounts of non-hydroformylated alkenes, hydrogenated alkenes and alcohols.</p>