Complete assignment of 1H- and 13C-NMR spectra of anthranilic acid and its hydroxy derivatives and salicylic acid and its amino derivatives

Abstract

We report on the detailed NMR spectral analyses of amino- or/and hydroxy-substituted benzoic acids: anthranilic (AA), 3-hydroxyanthranilic (3-HAA), 5-hydroxyanthranilic (5-HAA), salicylic (SA), 4-aminosalicylic (4-ASA) and 5-aminosalicylic (5-ASA) acids. According to a literature survey, there are limited, unassigned or even incorrectly assigned spectral data to these benzoic acid derivatives. In order to amend the situation, a complete assignment of 1H- and 13C-NMR spectra of these compounds, recorded in perdeuteriodimethyl sulfoxide (DMSO-d6), based on a combination of 1D- and 2D-NMR experiments, including 1H-1H COSY, NOESY, HSQC and HMBC, was performed.