[Watchdog]

For a project we had to react different chemicals with different reagents. I had cinnamaldehyde.


We also had to write down different reactions that occurred. When the cinnamaldehyde was reacted with concentrated H2SO4, it turned dark brown. I am unsure what reaction went on. I know the aromatic ring would not react, so I think the acid is either reacting with the aldehyde group to protonate the oxygen or the alkene group to add hydrogen across the double bond.
Can someone please point me in the right direction?