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.

POTPUNA ASIGNACIJA ¹H- I ¹³C-NMR SPEKTARA ANTRANILNE KISELINE I NJENIH HIDROKSI-DERIVATA I SALICILNE KISELINE I NJENIH AMINO-DERIVATA

U ovom radu dati su NMR podaci za antranilnu (AA), salicilnu (SA) i regioizomerne (amino)hidroksibenzoeve kiseline, 3-hidroksiantranilnu (3-HAA), 5-hidroksiantranilnu (5-HAA), 4-aminosalicilnu (4-ASA) i 5-aminosalicilnu (5-ASA) kiselinu. Kako je pretragom literature utvrđeno da su do sada objavljeni NMR podaci za pomenute derivate benzoeve kiseline nepotpuni, neasignirani ili čak i pogrešno asignirani, izvršena je kompletna asignacija signala u ¹H- i ¹³C- NMR spektrima snimljenim u deuterisanom dimetil-sulfoksidu (DMSO-d₆) kombinovanjem ¹H- i ¹³C-NMR sa ¹H-¹H COSY, NOESY, HSQC i HMBC eksperimentima.

HIGHLIGHTS

• The NMR spectra of anthranilic, 3- and 5-hydroxyanthranilic, salicylic, 4- and 5-aminosalicylic acids were recorded in DMSO-d_6.
• A literature survey revealed limited, unassigned or even incorrectly assigned spectral data for these amino- or/and hydroxy-substituted benzoic acids.
• Complete assignment of NMR spectral data was based on a combination of ¹H-and ¹³C-NMR 1D- and 2D-experiments (¹H–¹H COSY, NOESY, HSQC, HMBC).
• The ¹³C-¹H coupling constants, previously unavailable in the literature, were derived from the proton-coupled ¹³C NMR spectra.
• In the ¹H-coupled ¹³C NMR spectrum of 5-aminosalicylic acid two signals appeared as second-order multiplets, although first-order ones were expected.