1,8-Bis(dimethylamino)naphthalene (“ProtonSponge”) and bromomaleic anhydride react quickly at room temperature, generating 3-(4,5-bis(dimethylamino)napthalen-1-yl)furan-2,5-dione (4-maleicanhydridoproton sponge or “MAPS”). MAPS is a deep purple solid that exhibits positive solvatochromism in solution. It is a weaker base than ProtonSponge. When protonated in solution, MAPS loses its color, but the