Reduction of Alkynes Addition of H2 over a metal catalyst(such as palladium on carbon,Pd/C)converts alkynes to alkanes (complete reduction) The addition of the first equivalent of H2 produces an alkene,which is more reactive than the alkyne so the alkene is not observed HC≡CH H2 Catalys →H2C=CH2△Thydrog=-176kJ/mol(-42kcal/mol) H2 H2C-CH2 → 24ThomsonBrooks Coe Catalvst CH3-CH3 AHRydrog =-137 kJ/mol (-33 kcal/mol) Reduction of Alkynes „ Addition of H 2 over a metal catalyst (such as palladium on carbon, Pd/C) converts alkynes to alkanes (complete reduction) „ The addition of the first equivalent of H 2 produces an alkene, which is more reactive than the alkyne so the alkene is not observed