title: Complexing properties of N-methylpyridium alpha-amidooxime iodide (MAI) and spectrophotometric investigations on MAI aqueous solutions and its protolitic equilibria.
abstract: The effect of pH on electronic spectra of MAI was investigated. The N-methylpyridium alpha-amidooxime iodide (MAI) in water solution is hydrolized to weak base with log K2H = 10.14. At low concentration in water solution the geometrical isomers are likely to exist, yielding 4 isosbestic points in UV spectrum. In syn isomer the lone electron pair of -NH2 group is probably blocked through intramolecular hydrogen bonding with oxime group. The effect of hydrogen ions concentration on spectra of watersolution of MAI was examined within range Ho = -3.87 to pH 12.97. Determined protolitic constants are as follows: log K1H(pKa) = 12.14 dissociation of oxime proton, log K3BH = 4.02 - protonation of -NH2 group in anti isomer, log K3AH = 1.62 protonation of -NH2 group in syn isomer, log K4H = -2.42 - protonation of oxime nitrogen or oxygen.
authors.affiliation: Department of Pharmaceutical Analysis, Postgraduate Medical Education Center, Faculty of Pharmacy, Bydgoszcz, 3 Dabrowa Str., Poland.
authors.forename: S
authors.initials: S
authors.lastname: Zommer-Urbańska
authors.forename: M
authors.initials: M
authors.lastname: Kukliński
mesh_terms: D002021:Buffers; D004355:Drug Stability; D006860:Hydrogen Bonding; D006868:Hydrolysis; D007202:Indicators and Reagents; D010091:Oximes / Q000737:chemistry*; D011726:Pyridinium Compounds / Q000737:chemistry*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002021:Buffers; D007202:Indicators and Reagents; C477586:N-methylpyridium alpha-amidooxime iodide; D010091:Oximes; D011726:Pyridinium Compounds; D012996:Solutions