Alkenes and alkynes are rapidly reduced to the corresponding alkanes using sodium borohydride and
acetic acid in the presence of a small amount of palladium catalyst. The heterogeneous reaction is conducted
in open air at room temperature. Reactions typically afford conversions to the alkane product
of 98% or more within 15 min. The best solvent system was determined to be isopropyl alcohol, though
reduction also takes place in solvents such as tetrahydrofuran, chloroform and, with some substrates,
even in water. The method described is a convenient alternative to hydrogenations that require an external
supply of hydrogen gas.