# Why are carbonyl compunds more reactive towards catalytic hydrogenation than alkynes and alkenes?

Alkynes are more reactive towards catalytic hydrogenation than that of alkenes, because they are more unsaturated. This is the correct reasoning, right?

But why are carbonyl compounds more reactive towards catalytic hydrogenation than alkynes? The $$\ce{C=O}$$ in carbonyl group is polar, but how does that affect reactivity?

Example:

Answer: Option (D), $$c>a>b$$

• I doubt that it is carbonil group that is hydrogenated. It is more likely, that $C-Cl$ bond will be cleaved here. $COCl$ group is known to be very ready to react. Jan 15, 2013 at 7:56