Abstract: Hydrogen is supplied first to a last hydrogenation zone, and gases recovered from the last hydrogenation zone are passed to the first hydrogenation zone of a continuous multi-zone liquid phase process for hydrogenating an organic compound to a corresponding hydrogenation product. The organic compound, with a suitable diluent or recycle hydrogenation product, flows successively through the zones beginning with the first and ending with the last hydrogenation zone to undergo hydrogenation with the hydrogenation product being recovered from the last hydrogenation zone.

Abstract: A process is provided for the recovery of an optionally substituted C.sub.7 to C.sub.17 aldehyde from a liquid hydroformylation product medium obtained by rhodium catalyzed hydroformylation of an optionally substituted C.sub.6 to C.sub.16 olefin which contains (i) a rhodium complex hydroformylation catalyst containing rhodium in complex combination with carbon monoxide and with a ligand, (ii) excess ligand, (iii) at least one optionally substituted C.sub.7 to C.sub.17 aldehyde, and (iv) aldehyde condensation products, which process comprises:(a) degassing said liquid hydroformylation medium;(b) passing the degassed liquid hydroformylation medium through an evaporation zone maintained under temperature and pressure conditions conducive to evaporation of said at least one C.sub.7 to C.sub.