[zhishiji]

a schiff base was got through diketone and diimine,but I find that it's hard to be purified.I also want to know whether the exisitance of little water is not important to the reaction.

[english]

I also want to know whether the exisitance of little water is not important to the reaction.

Removing water drives the reaction to the imine.  Since an amino group is more basic than a hydroxy group, it's more favorable to protonate it during the reaction, not the hydroxy group. 

If you remove water (product formed from removal of hydroxy group), more imine will be obtained.