A method for increasing the solubility of industrial azo pigments for 13 C and 1 H NMR spectra and the assignments of their 13 C and 1 H NMR peaks

Meiling Zhu; Guangyuan Feng; Dongjun Lv; Nan Qin; Chunbao Li

doi:10.1002/mrc.5138

A method for increasing the solubility of industrial azo pigments for ¹³ C and ¹ H NMR spectra and the assignments of their ¹³ C and ¹ H NMR peaks

Magn Reson Chem. 2021 Aug;59(8):804-814. doi: 10.1002/mrc.5138. Epub 2021 Feb 15.

Authors

Meiling Zhu¹, Guangyuan Feng¹, Dongjun Lv², Nan Qin³, Chunbao Li¹

Affiliations

¹ Department of Chemistry, School of Science, Tianjin University, Tianjin, China.
² College of Chemistry and Chemical Engineering, Dezhou University, Dezhou, China.
³ School of Pharmacy, Tianjin Medical University, Tianjin, China.

PMID: 33559222
DOI: 10.1002/mrc.5138

Abstract

A method for increasing the solubilities of industrial azo pigments in DMSO by adding DBU (1,8-diaza-7-bicyclo[5.4.0]undecene) has been developed. This facilitated the acquisition of solution ¹³ C NMR spectra of the pigments. This method was applied to four types of azo pigments: naphthol AS (3-hydroxy-2-naphthoic acid anilide) pigments, naphthol pigments, pyrazolone pigments and acetoacetanilide pigments. This represents the first solution ¹³ C NMR spectra for naphthol AS pigments. Altogether 18 industrial azo pigments were analysed using 1D and 2D NMR techniques. The proton and corresponding carbon NMR resonances of these pigments have all been assigned.

Keywords: DBU; azo pigment; dimensional NMR; peak assignment; solubility; solution 13C NMR.

MeSH terms

Azo Compounds / chemistry*
Bridged Bicyclo Compounds, Heterocyclic / chemistry
Carbon-13 Magnetic Resonance Spectroscopy / methods
Coloring Agents / chemistry*
Dimethyl Sulfoxide / chemistry
Proton Magnetic Resonance Spectroscopy / methods
Solubility

Substances

Azo Compounds
Bridged Bicyclo Compounds, Heterocyclic
Coloring Agents
1,8-diazabicyclo(5.4.0)undec-7-ene
Dimethyl Sulfoxide