# Which proton is more acidic in this compound?

I'm having trouble determining which of these protons is more acidic. I was thinking the solution had something to do with the double bond in the aromatic ring, but I'm still not sure. If anyone can help, I'd greatly appreciate it.

• This should be a $C_2$ symmetric molecule, making the $\ce{N-H}$ protons equivalent. Generally, they are more acidic than $\ce{C-H}$ protons. – Martin - マーチン Sep 28 '14 at 7:03

## 1 Answer

You could start by drawing the resonance structure of the naphthalene ring, this gives a compound in which the conditions on the two nitrogen atoms are interchanged, thus both nitrogen atoms are equivalent. As N-H bonded protons are more acidic than C=C-H protons and N-C-H protons, the answer must be the hydrogen atom bonded to the nitrogen atom, as both nitrogen atoms are equivalent, either of the hydrogen atoms is a valid answer (as they are equivalent).