ABSTRACT
The catalytic hydrogenation of acetylenes is the most facile of all hydrogenation reactions, generally taking place in the presence of all other functional groups including conjugated dienes and aromatic nitro groups. The ease of saturation is enhanced if the triple bond is terminal. The complete hydrogenation of alkynes to alkanes occurs over all common hydrogenation catalysts at room temperature and atmospheric pressure. The selective hydrogenation of a triple bond to give an alkene without concomitant positional or geometric isomerization is particularly important in synthetic procedures and many industrial processes. In the absence of any isomerization, selective partial hydrogenation of a disubstituted alkyne produces the cis alkene. Small amounts of the trans alkene are sometimes formed in these reactions, but catalytic processes do not lead to the production of the trans olefin as the primary product.
