Imines are usually extremely unstable, unless they are structurally particularly stable, like coniugated π system.
Is extremely difficult to isolate them, because they are easily hydrolized. Resuming, starting reagents in imine synthesis reaction, aldehyde (or ketone) and amine are much more stable than the imine itself;
Here it is the imine hydrolisis reaction mechanism:
1) The imine is protonated. Iminium ion is very likely to be attacked by a nucleophile.
2) The nucleophile in this case is H2O, which attacks the iminium ion with π C−N bond break and forming of a new σ C−O bond.
3) There must be an inter o intramolecular protons exchange. Hydroxyl get rid of the charge while the amine become a good leaving group.
4) The oxonium ion loses a proton.