Reduction of Alkenes: Catalytic hydrogenation

Oxidation

loss of e-, more C-Z bonds

What are C-Z bonds?

N, O, or halogen

Reduction

gain of e-, more C-H bonds

neither

C-Z and C-H additions cancel out

Catalytic Hydrogenation

remove pi bonds and replace with 2 H atoms on each DB carbon atom with H2/Pd-C

3 metal catalysts

Pd, Pt, Ni bonded to C

Catalytic hydrogenation heat is

exothermic from breaking pi bond

more stable/substituted the alkene

the less energy it needs

to find larger heat of hydrogenation

less substituted alkene, cis isomer

less substituted alkene = rxn?

faster rxn, easier to bind to catalyst

Hydrogenation with excess H2 for aldehydes

reduce to primary alcohols

Hydrogenation with excess H2 for ketones

reduce to secondary alcohols

Hydrogenation with excess H2 for benzene rings

no reduction to ring