Hydrogenations are reactions of unsaturated molecules with hydrogen (H2). Precious metal compounds of rhodium, ruthenium, or iridium rank with the most effective homogeneous hydrogenation catalysts because of their outstanding selectivities.
Catalysts for hydrogenations are often equivalent to those for hydroformylations, where the reactants H2 and CO are applied.
Besides, C=O's, C=N's, and alkynes can be hydrogenated. Ruthenium in particular has an affinity for C=O bonds. Hydrogenations of imine groups could effectively be managed with iridium. On the basis of homogeneous ruthenium catalysts, ring hydrogenations are feasible, too.
Well-known are especially the "Wilkinson's Catalyst" and dichlorotris(triphenylphosphane)ruthenium(II) mainly for the hydrogenation of terminal C=C's.
Hydrogenations lead to chiral centres in prochiral molecules. Like right and left hands, "chiral" molecules of the same constitution (empirical formula, structure) can coincide only with their mirror-images. Chirality is extraordinarily important to modern agents in the field of life science, where almost just one chiral variant is active to a specific purpose. Such "asymmetric hydrogenations" are feasible in a very effective way by using precious metal precursors along with chiral ligands. Heraeus offers a broad range of such precursors relevant to industry, mostly organometallics.