The equilibrium position between a simple ketone and its enol usually lies far
on the side of the ketone .However, there are some interesting
and important exceptions to this generalization. For instance, the influence of
two carbonyl groups on the enol content is very striking, as we can see from
the fact that 85% of 2,4-pentanedione is the eno1 form at equilibrium:
thats y it SHOWS BROMINE WATER DECOLOURISATION