Hydrogenation of arenes, including the lignin model compound 2-methoxy-4-propylphenol, has been effected using a Rh colloid in biphasic aqueous/supercritical ethane reaction media; this is the first successful example of an unsupported colloid-catalysed hydrogenation of a substrate in a supercritical fluid; the same reaction does not proceed in aqueous/supercritical carbon dioxide or ionic liquid/supercritical fluid media.
