Nuclear Magnetic Resonance Spectroscopic Studies on the Action of Ammonium Chloride to Chloroquine

Abstract

In order to study the medically important action of ammonium chloride toward chloroquine or 7-chloro-4-(4′-diethylamino-1′-methylbutylamino)quinoline, the proton and carbon-13 nuclear magnetic resonance (NMR) spectra of chloroquine have been examined using a 400-MHz NMR spectrometer. Quinoline ring protons exhibited highly resolved coupling patterns of the first-order. The distortionless enhancement by polarization transfer (DEPT) spectra discriminated methyl, methylene and methine carbons in the diamino-chain where diamagnetic effects by nitrogen atoms are complicated. All assignments were fulfilled with carbon-proton correlation spetroscopy (COSY), besides homo-spin decoupling and DEPT spectra. The affinity of ammonium chloride with the chloro atom of the quinoline ring was observed in the proton NMR spectra. This fact seems to be related to the dose of ammonium chloride used to reduce the amount of chloroquine given to patients suffering from retinopathies.