1-aza-5-azoniaspiro[4.4]non-1-ene, 2-(2-hydroxyethoxy)-3-(methoxycarbonyl)-4-oxo-, inner salt 2-(2-hydroxyethoxy)-3-(methoxycarbonyl)-4-oxo-1,5-diazaspiro[4.4]non-1-en-5-ium-3-ide InChI=1/C11H16N2O5/c1-17-11(16)8-9(18-7-6-14)12-13(10(8)15)4-2-3-5-13/h14H,2-7H2,1H