Synthesis and Molecular Characterization of Diazonium Compounds Through the Reaction of Different Phenolic Compounds and Novel Aminothiophene Precursors as a New Class of Colorants

Jalali, Aazam; Rezaei-Seresht, Esmail; Ziyaee, Hoda; Maleki, Behrooz

doi:10.22034/jams.2025.210137

Synthesis and Molecular Characterization of Diazonium Compounds Through the Reaction of Different Phenolic Compounds and Novel Aminothiophene Precursors as a New Class of Colorants

Document Type : Original Article

Authors

Aazam Jalali ¹

Esmail Rezaei-Seresht ²

Hoda Ziyaee ²

Behrooz Maleki ³

¹ Department of Organic and Polymer Chemistry, Faculty of Chemistry, Kharazmi University, Tehran, Iran

² Department of Chemistry, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran

³ Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran

10.22034/jams.2025.210137

Abstract

Two novel 2-amino thiophene precursors were synthesized from cyclopentanone (or cyclohexanone), sulfur, morpholine, and malononitrile using the Gewald three-component reaction. The synthesis yields of these precursors were 97% and 90%, respectively. The resulting 2-aminothiophenes were then converted into diazonium salts, which reacted in situ with various phenolic compounds, including phenol, resorcinol, and α-naphthol, to produce twelve new azo products. The novel 2-aminothiophene-based azo compounds were synthesized with yields ranging from 58% to 72% for the first set, and 54% to 72% for the second set. Subsequently, the characterization of prepared compounds was performed using ¹H-NMR, FT-IR, UV/Visible spectroscopy, and elemental analysis. UV/Visible spectra confirmed the presence of the azo group (N=N) with absorption in the range of 362–510 nm, which is higher than the previously reported range of 350–370 nm. The increase in λ_max can be attributed to the existence of an auxochrome group in the molecular structure of the compounds. Additionally, all of the various analyses performed successfully supported the synthesis of the desired compounds.

Keywords

Synthesis

Azo compounds

2-aminothiophene

Diazonium salt

Phenolic compounds