This is the answer for a past chem test...
When trying to draw a possible mechanism myself, I thought that things could start off by H3O+ protonating the gamma carbon, breaking the double bond between C3 and C4.
Then there would be a positive charge on C3, and I thought that the alpha carbon would then be able to lose an H to the water molecule, and create a double bond between C2 and C3.
Alpha carbons are acidic, so I thought that losing a H would not be a problem for it...
Is this a viable mechanism as well...? If not, why MUST we start by protonating the carbonyl Oxygen?
I would like to know why it happens the way the answer key is drawn and not the way I had thought...
Thank you so much!