What is the product of an addition reactions between butanol and water?
There isn't one with butanol, but there is with butanal.
I think you mean butanal, not butanol. There is no addition reaction with butanol because it has no
With butanal, it looks like
or, in structural form,
The double bond on the fourth carbon opens to allow a hydroxyl group, which then lets the original oxygen bond to the remaining hydrogen.