The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Oxine N-oxide as an analytical reagent for the colorimetric estimation of Ce(IV) and its comparison with 8-quinolinol as a chelating agent》. Authors are Bhat, A. N.; Jain, B. D..The article about the compound:8-Hydroxyquinoline 1-oxidecas:1127-45-3,SMILESS:OC1=CC=CC2=CC=C[N+]([O-])=C12).Quality Control of 8-Hydroxyquinoline 1-oxide. Through the article, more information about this compound (cas:1127-45-3) is conveyed.
Aqueous solutions of Ce(IV) salts form stable brownish red H2O-soluble complexes when combined with alc. oxine N-oxide. The absorption is measured at 420 mμ, and Beer’s law is obeyed to 9.0 p.p.m. Ce. Th, U, and F- interfere and must be removed.
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Reference:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider