ABSTRACT
The most common use of heterogeneous catalysts in organic synthesis is for the hydrogenation of functional groups. While the hydrogenation of molecules containing a single functional group is a common synthetic transformation, selectivity in the hydrogenation of more complex substrates has become more important. These selective reactions can be classified as being chemoselective, regioselective or stereoselective. Selectivity is defined as the number of moles of the desired product divided by the number of moles of reactant consumed or the percent of desired product divided by the percent conversion. Chemoselectivity refers to the selective hydrogenation of one functional group in the presence of other groups that are potentially able to undergo hydrogenation. The degree of difficulty in obtaining such selectivity depends largely on the functional groups involved. Stereoselectivity, the production of one stereoisomer of the product in preference to another, is one of the more important applications of a hydrogenation reaction.
